Bulldog92

iTrader: (1)

Thank the Lord...I finally have WinALDL data.

Check out https://www.thirdgen.org/techbb2/sho...hreadid=216309 to find out how I finally managed to get my laptop to accept my WinALDL data...if you're interested.

Here is some background info on my car:

- Originally an L03 305 / T5 drivetrain
- GMPP 350 H.O. engine (brand new)
- 454 TBI w/80-90 pph injectors
- Edelbrock Perf RPM Air Gap intake
- T56 tranny
- SLP 1-5/8" headers w/o AIR tubes
- Catco 3" cat (about 1-1/2 years old)
- Smog pump delete
- EGR delete
- 350 ESC module
- 350 knock sensor
- Factory AXKW bin with BPC set @ 100, EGR On Speed @ 255, and Fuel Cutoff Speed @ 255
- DD SGI-5 to convert VSS from T56...still reading about 10-20 mph low (need to adjust dip switch settings)
- The engine runs EXTREMELY rich at idle and lower rpms while driving
- The engine is EXTREMELY difficult to fire when cold...have to spray carb cleaner in the throttle body to get it going

I let the engine warm up to a normal operating coolant temp of 160F and drove around for about 10 minutes at varying rpms. SO, here's my data:

www.barneswebdesign.com/20040103_233515_LOG.xls

Here are my limited observations:

- I'm staying in "open loop" almost the entire time except @ time = 812.8
- As a result, my BLMs are fixed @ 128 EXCEPT at time 812.8, where the car briefly goes into closed loop and the BLM jumps up to 194 (which was right before I shut the engine off)
- A BLM of 194 indicates an extremely lean condition, when in reality I'm extremely rich @ idle
- Everything else seemed to also go crazy when it briefly went closed loop; e.g. coolant temp of 1121F, speed = 80 mph while sitting still, 0 rpms, etc.
- I got a knock count of 91.6 @ time = 232.6 and 8 @ time = 812.8 (when it went closed loop)

I've done some searches and found where people that had problems going into closed loop mode discovered that the O2 sensor was not heating up properly with their headers. I've got SLP headers, so that may be part of my problem. I saw where TRAXION recommended going with a 4-wire AC Delco heated O2 sensor...does anyone have a part number on that? I also saw where a Bosch 13077 heated O2 sensor was used...I found that one for $50-60 online. Does anything from the data indicate this may be my problem?

Also, is there anything else I can learn from the data I collected? I've been reading through all of the tuning tips I can find, but it's a little tough to swallow some of that stuff. For example, I've seen how to adjust the VE table once you get some BLM data in closed loop mode...but what can you learn from open loop mode? Any ideas on how to address my difficulty with firing the engine or the rich condition I have @ low rpms?

Brent

iTrader: (1)

One thing that looks suspicious to me is the MAP reading.

It should vary with engine load. In your log it stays right around 103.

At idle you should see 40-50KPA in the MAP column.

My first thought is that the MAP sensor hose is not connected properly.

The IAC and TPS look suspicious also.

IAC counts should change, not stay at 80. They should increase as you open the throttle.

The TPS should increase from low to high not stay around 80-90.

Its almost as if you are in a limp mode of some type. Or your ALDL cable has got the ECM in ALDL mode. (see column AN, MW2:ALDL Mode (10k Ohms))

If you've got a 10K resistor across the ALDL connector that would cause it.

Bulldog92

iTrader: (1)

Thanks for the reply...you're right, those data points do look strange now that you mention it. However, I don't have a 10k resistor across port A & B on the ALDL connector...makes me wonder why it's kicking in and out of ALDL mode according to the data. Assuming that "1" means "on", it appears to be staying in ALDL mode about 90% of the time. Just for verification, here's a diagram of my ALDL cable...except I don't use R3 or R4:




Regarding the MAP data, can you tell me where this sensor is located so that I can verify its hose is hooked up properly? Also, could this have an affect on the other invalid data points, or are they exclusive of each other?

Regarding the IAC data, I may need to check my wiring for the IAC connector since I had to wire in a new connector for the 454 TBI (it's a different connection than for a 305 TBI like I used to have).

As for the TPS, that sensor was an exact match to the 305 TBI connector...I didn't have to do anything but plug it in when I installed the 454 TBI. I don't have a clue as to why it would not function properly unless the sensor itself is defective.

However, all of this bad data may simply be the result of the computer running in ALDL mode....which I don't understand. Any thoughts on what could be making it do that without the 10k resistor across the ALDL connector?

Grumpy

It's in some defaults, limp home mode, or the cable is out to lunch.

See if any codes were set.

How does the car run without the cable?.

being rich with the large injectors without any tuning would seem logical.

Bulldog92

iTrader: (1)

Thanks for the reply, Bruce...

Let me reference a quote from one of your old posts:

That considered, you're stating that I either have a defective ECM or a disconnected sensor....right? Just as an FYI, I have accidentally fired the engine with the ECM in diagnostic mode before (A & B jumpered)...could that have fried my ECM? Also, I think I may have a disconnected MAP sensor...don't really remember hooking that one up when I installed the new engine and 454 TBI. Is it just a vacuum line that hooks up to the throttle body? (forgive my ignorance on this one...tried doing a search but turned up nothin')

Amazingly, no codes were set...I was expecting to at least get a code 32 since I had to remove the EGR with the Air Gap intake.

Exactly the same...rough @ lower rpms due to being really rich.

No doubt...that's why I'm trying to get some data so that I can do some tuning. In fact, I've quote a few questions for ya:

1) Does the ECM apply fuel based on the VE table even when it's in open loop mode? In other words, once I figure out how to get the ECM to go closed loop, will the resulting adjustments I make to the VE table be applied when I first crank up the car? In other words, will this help my difficulty with firing the engine when cold and running rich @ lower rpms while in open loop @ startup? (it's really strange...the engine will fire with no problems once the engine is warm)

2) Are there any other bin adjustments I should be considering that would address my rich condition and startup problems?

3) Do you think that a heated O2 sensor will be beneficial at all in my situation?

Thanks in advance for the help...you guys rock

Grumpy

I'd start going thru the wiring.
Then the vacuum lines.
Something is way wrong.

There comes a time when I just give up trying to correct the universe about using the proper terms. Seems like soft fail mode just exists at GM, and here.

Personally, I dont use close loop.
But, I been at this for a while.
You might consider setting the closed loop enable temp to 235, and start with that, so your not fighting the BLs. You might have to make some serious changes to get things where you want.

You need to rough things out. Sometimes as you get close lots of various elements fall into place.

Just for openers, if you haven't done the BPC calc, you might try setting it to ~95 and starting there. Also trim back the min PW to say 2/3s of what it was.

With drastic changes like you have it's going to take some tinkering to get it roughed out.

You might look at my thread about tuning a stocker, and what my VE and timing tables look like. They are for a BBC, with the large injectors.

Bulldog92

iTrader: (1)

Well, I didn't have the line for the MAP sensor hooked up after all. I promptly plugged it up to the back of the TBI, fired up the engine (after priming it with carb cleaner), and now I have a NEW problem. The idle jumped up from an already-high 1300 rpm @ idle to about 2200 rpm. It runs at that level for about 30 seconds, then the idle drops way low and the engine acts like it's going to die, but then it jumps back up to 2200 rpm again. This just repeats over and over. It throws a code 21 (high TPS voltage) every time the idle drops low, by the way. I experimented with unplugging the MAP sensor and found that the idle dropped back down to 1300 rpm with no surging at all.

I read several posts about high TPS voltage...it appears to throw this code when the voltage jumps above 1.25V. However, I don't understand why it only does this when I hook up the MAP sensor. Do I have a defective TPS or MAP sensor? Or is something else going on? Any help will be much appreciated...thanks

Oh, and Grumpy - I have already set the BPC to 100 in my bin.

Edit - Forgot to ask if the weird TPS and IAC readings in my WinALDL data output could be the direct result of the MAP sensor not being hooked up...any thoughts? Would it help for me to log some more data with the surging routine going on?

Bulldog92

iTrader: (1)

Well, I decided to just go ahead and log some more data in hopes that it would help someone identify my problem. I didn't wait until the coolant temp hit 160F this time because I didn't want to run the engine that long with it running so badly and spitting raw fuel out the exhaust (even more so than "normal"). Here it is:

http://www.barneswebdesign.com/20040110_134852_LOG.xls

I noticed that the TPS voltage, instead of ranging from 74.1 - 82.3 as before, is now ranging from 84.7 - 89.5. The MAP is also ranging from 25.1 - 102.6 now as opposed to hanging around 102 the whole time. The IAC also seemed to stay at 104 now as opposed to 80 before, but that may have to do with the fact that the engine wasn't warm yet.

Any thoughts?

Brent

iTrader: (1)

Probably because the ECM is running in a limp type mode when the MAP is disconnected.

Sounds like the IAC and/or TPS may be wired incorrectly.

With the ignition on engine off, verify with Winaldl that the TPS reads approx .54V with the throttle closed. Then verify that the TPS increases to approx 4V as you slowly depress the accelerator.

Bulldog92

iTrader: (1)

The IAC very well may be wired incorrectly since I had to wire in a new connector for the 454 TBI. However, the TPS has not been tampered with due to it being identical between the 305 and 454 TBI units.

I attempted to check the voltages as you advised...however, I don't think I'm getting the right units or something. There are two types of TPS data: RAW and SENSOR (raw with some conversions, I presume). With the ignition on/engine off, the raw TPS stays at 202 and the sensor TPS stays at 84.2...neither of which appears to be a voltage reading (at least I hope not!). Once I fired the engine up, I really wasn't able to slowly depress the accelerator because the engine acted like it wanted to die. I could romp on it briefly and get the rpms to go up, though. The highest raw TPS with the engine running was 207 with a corresponding sensor TPS of 86.6.

Does that make sense?

Brent

iTrader: (1)

Hmmm, I thought Winaldl displayed volts. oops

Anyhow, thats is no matter as we can take the raw values and multiply them by the voltage factor which is .0196.

204 x .0196 = 3.9984V This voltage tells the ECM that you are at WOT.

Something is goofy with your TPS or wiring.

Pull the TPS off and make sure the lever isn't binding or stuck at WOT.

With the ignition on and engine off move the TPS lever through its range. Winalda should report low raw values (20-50ish) with the lever at idle. At WOT it should be over/around 200.

Bulldog92

iTrader: (1)

Well, I tried the TPS experiment with the ignition on/engine off...the raw TPS stays @ 202 the whole time, regardless of whether I have the throttle lever engaged or not. That makes me think I have a defective TPS...right?

Oh, and I tried to pull the TPS off and broke off a bolt head in the process....arghhh! Now I've got to take my TBI to work AGAIN (been here before...guess I'll never learn to use pentrating fluid on rusty bolts) and drill and tap it.

Also, I went ahead and checked the IAC voltages with the ignition on/engine off and they were as follows:

A - blue/white - 0.4V
B - blue/black - 11.5V
C - green/white - 0.4V
D - green/black - 11.5V

I thought these were supposed to Hi/Lo, Hi/Lo instead of Lo/Hi, Lo/Hi...right? I saw that sniper_dsl had to swap the green wire on his IAC connector in this thread https://www.thirdgen.org/techbb2/sho...64#post1513764, but it looks like I might should switch both my blue AND green wires to get the correct Hi/Lo voltage...what do you think?

Brent

iTrader: (1)

TPS sure sounds like it's bad.

I'd test it before replacing it though. Unless you have one you can swap in quick.

Take you DVOM and measure OHMs between pins C and B. The resistance should increase from idle to WOT.

Measure between C and A. The result should be the opposite of the first test. The resistance should start high and fall low as you approach WOT.

As for the IAC, I'd follow Rbob's diagram at:

https://www.thirdgen.org/techbb2/sho...IAC+AND+wiring

D - blue/white
A - blue/black
B - green/white
C - green/black

The voltages you measured don't mean anything. They switch as the IAC runs.

Bulldog92

iTrader: (1)

Thanks, Brent...I'll be sure to check the resistance across the pins tomorrow afternoon, but I'd bet the farm that I've got a bad TPS. You know, that would perfectly explain why I'm running so incredibly rich...the ECM always thinks I'm at WOT. That also explains why the car runs without a problem when I actually am at WOT. I'll also re-wire the IAC if it doesn't work properly once the TPS problem is resolved.

I really appreciate all the help...I'd be in trouble without this board.

Bulldog92

iTrader: (1)

Well, I attempted to measure the resistance across the pins as you advised, Brent. I am assuming that you mean to check the resistance across the pins on the TPS itself with the connector disconnected...is that correct? I couldn't think of any other way to do it, unless you actually penetrated the wires themselves with the connector connected. Anyway, I measured an 11K resistance across C & B as well as C & A that did not change regardless of how I engaged the throttle lever on the TBI between idle and WOT. I guess that means that either the lever is not engaging the TPS or the TPS is toast. What do you think?

Brent

iTrader: (1)

TPS is toast.

The resistances should change as you sweep the TPS from idle to WOT.

Can you pull the one off your stock TBI and try it out?

Bulldog92

iTrader: (1)

Now, there's a novel idea. I totally forgot about the TPS on my 305 TBI...guess I didn't realize they were identical. Anyway, I'll be sure to check that out tonight and try to get them swapped-out because I'm hoping to get my "broken-off bolt problem" resolved today at work.

Bulldog92

iTrader: (1)

Well, I've got good news and bad news.

The good news is that I swapped-out my TPS and it is now working like it should. I am getting raw TPS data ranging from 24 @ idle to 221 @ WOT, or 0.47V - 4.33V using your conversion. The extra bonus is that my car now starts ALL ON ITS OWN...which is a major success since it always required carb cleaner fluid as a primer before.

The bad news is that, after I installed the replacement TPS, I fired up the engine and it repeated the same surge to 2000 rpm, followed by a sudden drop in rpm and almost dying, back to 2000 rpm, etc. I re-wired the IAC according to your recommendation and it repeated the same problem.

Here is some data I logged after I re-wired the IAC in case it helps at all:

www.barneswebdesign.com/20040112_210357_LOG.xls

As you can see, I am now also getting fluctuating IAC data between 0-160, as opposed to the fixed 104 value before. It looks like the issues with fixed MAP, TPS and IAC data have all been resolved, for that matter.

Yet, the surging problem persists...any thoughts? I just know that this car is almost ready to get back on the road...one last problem to resolve...

One more thing...I just noticed that the MW2:ALDL Mode is still bouncing back and forth between 0 and 1. I would have thought that problem would have been resolved by hooking up the MAP sensor and replacing the TPS. Strange, huh?

Brent

iTrader: (1)

Excellent!

It just occurred to me why you needed starter fluid before! When the ECM reads approx 80% or more TPS it goes into flooded mode and cuts starting fuel WAY back or off completely (can't remember which).

I looked at some winaldl data from other cars and they showed 1's in that 10K mode column also. Doesn't seem right but.....

The IAC data looks good. It starts off high at 160, till frame 17.7 where it appears you just started the engine. Then it starts to fall as it should.

The problem is, the RPM's don't fall as the IAC counts do.

Here's what I'd try:

Remove the idle speed screw cover.

Perform the IAC reset/ minimum idle procedure.
Take the paper clip and insert the clip ends into the ALDL in the 'A' and 'B' pins.

Turn on the ignition, but don't start the engine. Wait 30 seconds. Now, go remove the connector from the IAC (it should be making a clicking sound).

Ignition off, remove paperclip.

Start the engine and adjust the idle down to 500rpm with the screw. (you may have to give a little throttle to start it.)

Shut it off and plug the IAC back in. Cycle the ignition to run and off once.

Start the engine w/Winaldl connected. It should rev up to 1500-2000 and then slow down as the IAC counts decrease.

If not then the IAC is wired wrong or junk.

I looked on Mitchell and they show different IAC pin outs for the '91 and '93 7.4L trucks. Maybe try the '93...

'91 (same as stock L03)
C - grn/wht
D - grn/blk
B - blu/blk
A - blu/wht

'93
C - grn/wht
B - grn/blk
D - blu/blk
A - blu/wht

Bulldog92

iTrader: (1)

Well, it appears that my problem just got weirder...I started going through the steps of setting the idle. I jumpered pins A & B, turned on the ignition (not the engine), waited 30 seconds...no clicking sound from the IAC. I thought that I may have heard a single "click", but I wasn't sure. I looked and I could see the tip of the IAC piston when looking from the top of the TBI, but I couldn't tell if it was seated or not. I went ahead and unplugged the IAC connector anyway.

So, I thought that I'd go ahead and try setting the idle and see what happened. I located what I thought was a "plastic" cover on the front of the TBI on the driver's side and attempted to remove it to gain access to the idle set screw (see scratched-up area of TBI in pic...ha). It is apparently made of metal on a 454 TBI and cannot be removed...at least I couldn't.

Since I couldn't adjust the idle, I thought that I'd at least go ahead and fire up the engine (after removing the jumper b/w A & B) just to see if it behaved OK without the IAC interfering. Amazingly, it did exactly the same thing as before ...surging to 1500-2000 rpm, almost dying, over and over, etc.

Now I'm wondering what in the world is going on...what would cause this surging/dying cycle aside from the IAC? Any thoughts?

Brent

iTrader: (1)

That plug will come out. You may be able to jab an awl into it to pry it out. If not, drill a small hole in it to facilitate removal.

If you don't verify that the throttle idle screw isn't the source of the high idle you might chase your tail.

Go through the min idle procedure again once that plug is out.

If the idle speed screw can't slow down the idle then stuff a rag in the IAC air inlet to see if that makes a difference.

If the rag slows the idle down then I'd try wiring the IAC differently.


One comment on the picture. I see three hoses coming off the front of the TBI.
Correct me if I'm wrong:
-One leads to a PCV (the large one)
-the one on the right leads to the charcoal canister
-the one on the left is plugged because you no longer use EGR

Bulldog92

iTrader: (1)

I thought about drilling it out, but wasn't sure as to exactly what was behind it. The cap looks totally different on the 454 TBI as opposed to the 305 TBI...it appears to be a rounded, solid metal piece while the 305 version looks like a flimsy sheet metal plug that was driven into place or something. I'll take your word for it and drill it out tomorrow night. We'll see what happens!

Regarding the hoses:

-One leads to a PCV (the large one)
yes

-the one on the right leads to the charcoal canister
actually, it's the one on the left under the large hose...gee, I thought that canister was for the cruise control or something

-the one on the left is plugged because you no longer use EGR
the one on the right is plugged because I no longer have a "thermac" system on the intake...I think that's right, anyway

And FYI, there is one hose coming off the back of the TBI for the MAP sensor...which is the one I initially forgot to hook up (oops).

Oh, one more thing...do you have the Mitchell wiring diagram for a '95 7.4L truck? That is the year of the truck my TBI was on...but it may have the same IAC pin out as the '93.

Brent

iTrader: (1)

That plug might be steel. It should be a welch plug though.

Hoses sound right.

I'll look up the '95 IAC wiring tomorrow.

Brent

iTrader: (1)

'95 7.4L truck IAC

C - grn/wht
D - grn/blk
B - blu/blk
A - blu/wht

This is the same pinout as the L03.

Mitchell lists the truck 7.4L as using the 17113099 IAC from 89-95.

The truck and fbody 5.7L & 5.0L use the 25527077 IAC from 89-95.

What a mess eh? Mitchell seems to have some errors in their wiring diagrams and maybe even there part # database. argh

If I had to bet; the pinout will be the one Rbob lists or the '93 pinout I listed above.

Bulldog92

iTrader: (1)

Ahhh...another night of fun with myCamaro.

After much pounding, drilling, and slicing (yes, I broke out the Dremel) I was at least able to put a hole in the metal SLUG covering up my idle set screw (see pic...it's pretty sad). That done, I started over with the minimum idle procedure. I jumpered A & B, ignition on, waited 30 seconds...this time I noticed that the IAC was making a small humming sound, no clicking (it was probably doing this last time, too...I just couldn't hear it). Next, removed IAC connector, removed jumper, ignition off, and started the engine. After I figured out that the idle set screw is a Torx T25 screw and NOT a Phillips (duh), I was able to reduce the idle. Here is the data I logged during this procedure:

www.barneswebdesign.com/20040114_213328_LOG.xls

As you can see, the raw TPS value steadily fell from 23 to 13, which is when I realized that the screw wasn't even touching the throttle linkage anymore (oops). Of course, I still had the surging action going on...but you can see that, when the engine idled down, it actually dropped as low as 225 rpm with the butterflies completely closed (i.e. the idle set screw completely disengaged). It is very difficult to attempt to set the idle when the engine is revving up, down, up, down...you get the picture. Looking at the data, it appears that setting the raw TPS value to 17 results in 525 rpm...guess I'll bump it back up to that level.

Since the idle screw adjustment had no impact on the surging problem, I decided to take your second recommendation and stuff a rag down by the IAC with the engine running to see if the idle dropped at all. Upon doing so, the IAC valve attempted to ****** the rag out of my hands! Guess I can pretty much ascertain that my IAC valve is NOT closing when I jumper pins A & B (ha).

With all fingers pointing at the IAC at this point, I still am confused about something...if the IAC valve is fixed in one position with the connector removed, what is causing the variation in rpms? The valve is mechanically locked into position, yet it is acting like it is opening and closing or something. Can you help me out with that one?

I currently am using RBob's IAC pinout diagram, but can easily try out the '93 7.4L pinout you mentioned. However, I am starting to get a little short on wire because I lose some length every time I cut out the old splice joints...hopefully I nail it this time! (ha) I know that it must be currently wired incorrectly, otherwise it would have closed when I jumpered A & B.

One thing still concerns me...even if I have the IAC wired up correctly, why is the engine speed changing with the IAC disconnected? That just doesn't make sense to me...I hope you can shed some light here, 'cause I'm totally in the dark.

Oh, and by the way...I totally appreciate all of the help you've offered...you have gone way beyond the call of duty here.

Bulldog92

iTrader: (1)

Wow, I just noticed that I forgot to replace the plugged vacuum line! (see prior pic) Let me go out there and try firing the engine again to see if there is any difference...

Edit: Uhmmm...it just hit me that that little vacuum line is nothing compared to the massive vacuum leak I had going on through the open IAC valve. I seriously doubt it will make much of a difference at this point...plus it's almost 10:30pm and my neighbors are gonna hate me if I fire up my incredibly loud engine right now

Brent

iTrader: (1)

ARGH. I sure was hoping the surge would stop as the engine slowed down.

Well, atleast we know the IAC is either failed or wired wrong.

The surge problem. I'd tend to eliminate as many variables as possible. Pull out the 454 injectors and custom prom. Install the stock PROM and 305 injectors. They worked fine before right? That's probably the most straight forward route with known parts.

<b>BUT</b> The problem is probably in the PROM and not mechanical so hopefully someone else will be able to shed some light on this surge.

The engine should start and run smoothly enough so you can iron out the IAC issue.

Once the IAC is working right, then you can put the real injectors back in and start tunin.

RBob

iTrader: (1)

Bulldog92, as long as there are no vacuum leaks the surging is being caused by the engine speed/load transitioning between wanting to run and not wanting to run. Make sure to check & double check for vacuum leaks first.

If the engine is still surging then try this: unplug the IAC, start the engine and get it up to temperature (hold the go-pedal if need be). Start data logging. Hold the RPM (with the go-pedal) at a point where the engine will run w/o surging, probably about 1600-1800 RPM. At this point the ECM should drop into closed loop. If it doesn't just continue anyway.

Hold that speed for 5-10 seconds to collect some data. Then lift a little bit to lower the RPM and hold steady. Collect some more data (5-10 seconds). If in closed loop then can hold it longer for the INT/BLM to adjust.

Keep lowering the RPM in steps until it starts to surge. Adjust the go-pedal to keep the surge right on the edge. IOW you want the engine to just about surge, IE: have trouble actually holding a smooth RPM.

If in closed loop the surge should diminish as the INT/BLM adjust. If not down to an idle speed yet, reduce the go-pedal some more.

Once down around the idle RPM save the data log and shut the engine off. Using the data log of INT/BLM/O2 data adjust the VE table.

Taking a look at the last data log you posted I'll say that you are going to find the engine lean at the idle speed(s) and rich at the higher speeds. This lean idle area is causing the surge. Then once in the higher RPMs the rich allows the engine to smooth out and try to return to idle. Whereby the lean surge occurs again.

Notice how the O2 drops as the engine RPM comes down from the surge. Then as the engine surges the O2 increases. It is bouncing between 50mV and 800mV (or there abouts).

If the higher RPM was also lean the engine would surge high then die.

RBob.

Bulldog92

iTrader: (1)

Thanks for the great advice, guys. RBob, is there an easy way to check for vacuum leaks, other than visually inspecting all of the vacuum lines, plugs, etc.? Should I spray soapy water on everything with the engine running, or something like that?

One area of concern I have regarding leaks is my TBI-to-carb intake adapter...I bent the snot out of it when I originally installed it because I forgot to shorten the TBI mounting bolts. I just kept crankin' them down, not realizing that they were actually passing through the bottom side of the adapter plate and hitting the intake! Not exactly one of my brightest moments. We fired up the engine for the first time and it immediately raced up to an ungodly rpm level...man was that scary. It didn't take long to figure out our screw-up.

We ended up flipping it over the other way and bending it back, but I know that it is not completely flat by a long shot. My buddy helping me do the swap felt like it was tighten down OK and that the gaskets would probably absorb whatever gap was left, but I still don't feel that good about it. I'll bring some 0.001" - 0.010" feeler gages home with me today and stick them under the adapter plate to see if there is any gap. If so, I'm just going to make my own adapter this time because the Turbo City piece is junk.

If I don't find any vacuum leaks, I'll run through the procedure you outlined. It may be difficult to get it to hold at a certain rpm, though...the engine really behaves erratically. That'd be great if I could get it to go closed loop long enough to get some INT/BLM data so I can modify the VE table.

That's a good observation regarding the O2 flucutation with rpms...your theory makes sense. Basically, I think you're saying that the ECM detects a lean condition via the O2 sensor @ low rpms, dumps more fuel to compensate, detects a rich condition via the O2 sensor @ high rpms, cuts fuel to compensate, etc...correct? If that's the case, VE table adjustment should solve the problem. I'm staying optimistic...

RBob

iTrader: (1)

It may be tough looking for vacuum leaks as the engine doesn't want to settle down. Folks have used everything from spraying water, carb cleaner, degreaser around to using an un-lit propane torch (such as for plumbing) around the area. A change in how the engine is running would indicate a leak.

Can also blow smoke into the intake manifold or even compressed air and use the soapy spray and look for leaks.

No to the surging. This is the engine itself responding to the change in AFR. An engine will surge in RPM as the AFR goes lean.

RBob.

Bulldog92

iTrader: (1)

Not quite sure what you mean...do I just have the rich/lean theory backwards?

Anyway, I ran out of time to work on the car tonight...it'll have to wait until tomorrow night now. I'll be sure to post my results...thanks for the help.

RBob

iTrader: (1)

The surging isn't being caused by the ECM compensating via the O2 reading. IIRC your data log showed the ECM to be in open loop which means that the ECM would not be compensating in any manner.

It is the lean AFR at lower RPMs that is causing the engine to surge upward in RPM. Look at the last data log you posted notice as the RPMs drop the O2 reading does also.

RBob.

Bulldog92

iTrader: (1)

Ohhhh....I get it. I wasn't thinking...I forgot that the system has to go closed loop before it starts trying to force a 14.7 AFR. That considered, let me see if I understand the goal here: the ECM is always looking at the VE table to determine how much fuel to apply @ varying rpm levels, regardless of whether it's in open or closed loop. The problem is that I need to go closed loop in order to know how to change the VE table, which will address my lean condition @ low rpms and rich condition @ high rpms...correct?

BTW, I plan on trying out your advice tomorrow afternoon when I get off from work. I'll let you know.

RBob

iTrader: (1)

Yes to the ECM always using the VE table open or closed loop. As for getting the ECM to go closed loop for the tuning, it can help a lot. Given enough time at each RPM/Load point the BLM can be used to define how far off the AFR is.

If it won't go close loop (unusual as it should) you can use the O2 sensor to know whether it is rich or lean, and a vague idea of how much.

RBob.

Bulldog92

iTrader: (1)

Well, I finally had some time to get back on my Camaro project. RBob, I took your advice and first checked for vacuum leaks. A friend of mine told me to check for leaks by spraying some carb cleaner around all of the vacuum lines and the base of the TBI...the engine will rev up if some of the carb cleaner gets sucked in through a leak. I did just that and the only vacuum leak I found is through the open IAC valve (remember, I never was able to get it to shut). Would that be the reason the car idles so high? Maybe I should go ahead and try a couple more wiring combinations...

I also decided to go ahead and try the data logging routine you mentioned. I wasn't able to follow it exactly, though...the engine simply would not hold any certain rpm. I could hold the pedal at a certain level and the engine would STILL start to die, regardless. The engine also makes loud popping sounds when it starts to die, but I'm not sure if you'd actually call it a "backfire". However, I managed to get the engine to temperature by constantly patting the gas pedal and keeping it between 1500-2500 rpm.

Amazingly, shortly after I started logging data, the engine just stayed right around 1900-2000 rpm all on its own with the engine warm (coolant temp >160F). Something else to note is that I finally went closed loop and started getting some BLM data. All of my BLMs were above 128, which supports your theory that I'm lean @ lower rpms. Interestingly, the BLMs held steady @ 150 once the engine locked into its high 1900-2000 rpm idle. I don't know if that is enough info to base a VE table change on, though. However, if I did, would I increase all of the the VE table values @ 2000 rpm by 150/130=15% since the BLM was @ 150 and the INT was roughly 130? I may be way off base there...shed some light if need be. You can see the data here:

www.barneswebdesign.com/20040125_040550_LOG.xls

You can see where I would pat the gas every now and then to see if it would change anything. All that did was drop the rpm down to about 1700, after which it quickly returned to 2000 rpm. I stopped logging data after about 5 minutes and shut the engine off.

I let it sit for about 5 minutes, cranked it up, and started logging again. Interestingly, it behaved completely different this time. It started out OK and idled @ 1500 rpm, but then it started idling back and forth between 1500-1700 rpm (I wasn't touching the gas pedal) AND it threw a Code 44 for an O2 sensor lean error. I was also getting varying BLMs again, but they just bounced back and forth between 128 and 145 as the rpms varied between 1500-1700 rpm. You can see that set of data here:

www.barneswebdesign.com/20040125_041436_LOG.xls

Do you think this means I have a bad O2 sensor, or is it just saying I'm running lean? I could have VERY easily fouled it when I was having so much trouble cranking the engine several weeks ago with all of the black crud that's been coming out of my tailpipes. Any ideas?

Brent

iTrader: (1)

Not wanting to butt in on Rbob, but I have a theory about this situation.

Looks like Rbob is right, the VE table is heinously lean. The BLM and INT reflect that.

The question is, why is it so lean when there are 454 TB and injectors installed? Normally this would result in a Rich condition.

My thought is this. Your TB came off a 95 truck right? The fuel pressure spec for 94-95 454's is 26-32psi not the 9-13psi the 305 and 350's use.

If I remember, you removed the heavy 454 fuel pressure spring and replaced it with the stock L03 spring.

This 20psi reduction in fuel pressure makes your 454 injectors flow like L03 injectors.

On top of that, you lowered the BPW to 100 which further exacerbates the lean condition.

You could quickly confirm this by running a stock copy of your bin and loggin the BLMs. They should be closer to 128 if what I'm thinking is true.


The O2 could be fouled and contributing to the problem. When O2s foul they tend to tell the ECM things are lean and the BLMs start to read > 128. If the O2 is part of the problem its probably a small fraction.

Brent

iTrader: (1)

The IAC might be junk. Some testing is in order.

1)Unplug the IAC, take your DVOM and measure the resistance between IAC pins A and B. Assuming A and B are connected to the same coil inside the IAC your DVOM should read 40-80ohms.

2)If it meets spec, measure across C and D. Should also be between 40-80ohms.

3)If that meets spec, measure between A and C. You should not read any resistance as these are supposed to be electrically seperate. Also measure between the IAC housing and A,B,C, & D. You shouldn't find any resistances there either.

If any of these tests fail, the IAC is trash.

HOWEVER, If the first two tests fail......

Its possible that A and B don't connect to the same coil. So you will have to test between A and the other three to find what the pairing is. Could be A and C make a pair and B and D do. You'll jsut have to test.

If all the tests pass with flying colors then rewire it using temporary connections. I'd start back with the stock pinout and try the IAC/ Min idle resets procedure. One of the pinouts should seat the IAC. <strike>If not, then pull the IAC out and gently try to turn/move the pintle by hand. It should move fairly smoothly.</strike> Didn't realize that is a no-no. Sorry for the bad advice.

JPrevost

FWIW, if you think the IAC is an issue that is masking some other problems, just disable it all together. Limit your throttle follower steps to 0 along with actual limited IAC steps to 0. Then do the paperclip in the aldl, turn ign on, wait until the IAC stops making a loud noise, unplug IAC now that it's closed completely, turn off ign, pull out paperclip, and see where that puts you. You might need to have the throttle cracked open a little to get the car to start. Don't worry about this, just get the engine warmed up and try and lift your foot up as much as possible to get the car to idle on it's own.
Like Brent said, injectors are rated at different fuel pressures. You'll need to increase the fuel pressure a lot. For our engine I would go with at least 26psi to be safe. If those are the later model injectors then you might need to go up as high as 35psi, I don't know. I was under the impression that the BBC injectors were still rated at the lower fuel pressure and that only the L05 injectors in the later years up until 95 had the increased fuel pressure. I honestly don't know and this is one thing that really should be figured out.
You might also want to look into using an ANLU bin as the starting point and make changes for the manual trans. The ANLU still has the shift light code, it's nothing more than a flag that needs to be set to tell it which trans you've got. There might be other stuff, I haven't looked into it as of late but just do a bin compare and right down the locations of differences. Then go into the hack file and look at which tables or constants are different.
I can send you a bin file through e-mail that might make your life a little easier.
On the note about oxygen sensors. I would definatly go with a heated o2 sensor if you drive the car in cold weather. It's nice having a warm sensor for when you're on the highway and it's freezing cold. Although the SLP headers are stainless, they still cool down faster than stock iron manifolds hence the heated sensor requirement. Take a look at c4 vettes. They have stainless headers and guess what, a heated o2 sensor . For a quick patch in job install a relay that is similar to the fuel pump and fan relays up on the drivers side firewall. You can then have the relay for the sensors heating elements come on with the fuel pump. This is how I did it and works great! Off subject, anybody know the amps off hand for the heating element on the oxygen sensors?
I hope this helps and good luck getting it running smooth. I might be asking you for some help in the future with the t56 .

RBob

iTrader: (1)

Bulldog92, between Jon & Brent you received good advice. Also wanted to let you know that I'm still here. The IAC can be a problem child. The 454 TB also has a larger orfice for the IAC air bypass. This makes it react stronger then one of the smaller TBI units. Not a big deal, just something to keep in mind.

To help verify IAC operation do what Jon outlined and seat the IAC closed (ignition on, short A&B on ALDL, IAC should close). Can verify that it closed by looking down IAC air intake area on top passenger side of TB.

Ignition off, remove jumper, wait at least 10 seconds, then ignition back on. Wait a few seconds (once SES blink takes place) and ignition off. When the ignition is turned off the IAC should retract to the park position which is partly open.

These steps will help in verifying that the IAC is operational and not wired backwards.

If you take the IAC out don't try to turn the shaft. Most are keyed to the housing to prevent them from rotating. If the key gets sheared off (easy to do) then the IAC will not operate properly. The shaft doesn't rotate in operate it just extends or retracts.

(I say most are keyed because I did find an aftermarket IAC that uses a different printle spring configuration. In this IAC the spring was keyed into the pintle head and also the IAC body. The shaft was able to turn against the spring pressure, with the spring returning back).

You can also take the IAC out of the picture while roughing in the cal. Extend it (A&B/paperclip) and unplug the connector.

RBob.

Bulldog92

iTrader: (1)

Thanks for all the input, guys.

Brent - You're right about me swapping the 454 fuel pressure spring for the stock L03 spring...at the time, I thought I needed to because I was running SO rich. Plus, I didn't think I could actually compress that stiff 454 spring enough to get the regulator back together! However, the stock L03 fuel pump maxes out @ about 15 psi, right? Seems like I'd get the same 15 psi with the stock L03 spring compressed all the way as I would with the 454 spring fully compressed...maybe I'm wrong, though.

Anyway, I also did the resistance check you recommended. I may not have any clue as to read my multimeter, but I got a value of 19 with the meter set on "X 10" ohms between pins A-B and C-D. Does that mean I measured 190 ohms (19 x 10) or just 19? Either way, it's not within the 40-80 ohm range you said it was supposed to be. Also, I got zero resistance between A-C and B-D. Do you think this means my IAC is junk?

I decided to go ahead and rewire the IAC back to the stock pinout anyway to see if it would work...nothing. Here's all of the pinouts I've tried:

RBob's recommendation
A - blu/blk
B - grn/wht
C - grn/blk
D - blu/wht

Stock L03 (also same as '91 and '95 7.4L truck per Brent)
A - blu/wht
B - blu/blk
C - grn/wht
D - grn/blk

sniper_dsl's pinout (swapped greens...see https://www.thirdgen.org/techbb2/sho...4#post1513764p
A - blu/wht
B - blu/blk
C - grn/blk
D - grn/wht

'93 7.4L truck
A - blu/wht
B - grn/blk
C - grn/wht
D - blu/blk

Random combo
A - blu/blk
B - blu/wht
C - grn/blk
D - grn/wht

None of these pinouts made the IAC fully seat when I jumpered A & B...it didn't make the "loud clicking noise" either. I now assume that I either have no clue as to how to wire the IAC or the IAC is junk. Any thoughts?

JPrevost - As you can see, I am not able to close the IAC valve using the reset routine. Also, I don't understand what you mean by "Limit your throttle follower steps to 0 along with actual limited IAC steps to 0"...can you shed some light?

Regarding fuel pressure, won't I have to get a Walbro pump to get up to 26 psi? I think that's the fuel pump I've seen people go with, anyway. However, if the BBC injectors are actually rated as 80-90 pph @ 10-15 psi, would I still need to bump up my fuel pressure?

As for the ANLU bin, I thought about starting out with it before, but I saw where someone said it would be better to start off with the stock AXKW bin because the ANLU bin is for an automatic. I'll definitely take your word for it, though, since you've got the same engine I have. I'm using your ECU file (is this the "hack file" you mentioned?) named 8746jonprevost-twistid.ecu...can I use it for the ANLU bin as well as the factory AXKW bin? By the way, I'll gladly accept any bin file you have that would help me out...my e-mail is scbaeb@bellsouth.net.

The coldest it gets down here on the Gulf Coast is about 25 degrees in the winter, so I don't know if it's necessary for me to get a heated O2 sensor. However, my headers may necessitate it...any thoughts?

Lastly, RBob, I did take out the IAC to check the resistance across the pins, but I didn't try to turn or move the shaft in any way.

In summary, it looks like I've got to get my IAC problem worked out before I can really move forward with anything else like VE table changes...just let me know if you think my IAC is toast or not. Thanks!!!

Brent

iTrader: (1)

I was hoping that the IAC resistance testing would reveal some obvious flaw like one coil reading much higher or lower than the other. With both reading 190 ohms I'm hesitant to steer you towards buying a $100 part. On the other hand it is double the spec..

Regarding the A-C and B-D resistances, I used the wrong term. You should have infinte resistance between these, not 0 resistance (meaning a dead short). This is what you were indicating, correct? Sorry for the confusion. If you did in fact find 0 resistance between A-C and B-D then the IAC is trash.

Is this a digital meter? Not wanting to sound insulting but does it read 0 ohms when you cross the test probes?

Anyhow, one thing we know for sure is that A & B, C & D are pairs in the IAC. This means that each pair must use the same color wire. This narrows the valid pinouts down to either the Stock L03, SniperDsl's or the random combo pinout.

Before you buy another IAC I'd try this to eliminate the ECM as having faulty IAC drivers:

Install the 454 IAC again if it isn't and leave disconected. Temporarily wire the 305 IAC with appropriate pinout. Lay it on top of the aircleaner or rain tray were you can see it from the drivers seat. Start and run the engine long enough for the IAC start extending. The 305 IAC should extend as the ECM tries to slow the engine down. Shut the engine off and the 305 IAC should pull back inside its housing.

If the 305 IAC works then the 454 IAC must be shot as far as I can tell.

Bulldog92

iTrader: (1)

Yes, I should have said infinite resistance...I just knew that the needle didn't move, but the needle was sitting on infinity. Obviously, I don't have a digital meter (see pic)...it's more of an AutoZone analog multimeter special . The meter reads a value of 9 when I touch the probes together with it set on "X 10" and it reads 7.8 when I have it set on "X 1K". You can see these settings in the lower right corner of the dial on the meter. Those readings sound fishy...am I supposed to get zero resistance with the probes touching?

I'll try actuating the 305 IAC with the reset procedure tomorrow night...I'm curious to see how it turns out. Before I buy another IAC, I'll probably go ahead and try the other 13 possible pinout combinations (2x2x2x2 possibilities...why not).

I checked out a new IAC on gmpartsdirect.com and found that P/N 17113099 is actually only $62.70 including shipping and handling...but hopefully I won't have to go that route.

Brent

iTrader: (1)

They sure do. Yep, should read zero.

There should be a thumb wheel recessed in the side of your meter. Turning this will allow you to zero the meter. Select the range X10 ohm, cross the probes and turn that wheel until the meter reads zero. If there is no wheel or it won't zero the batteries might be low. In either case consult your meter's directions. Last resort, beg/borrow a meter that does zero.

Maybe consider calling around to some GM dealerships and garages to see if they'll test your IAC. Someone has to have one of these: IAC Tester

Bulldog92

iTrader: (1)

Thanks for the multimeter lesson, Brent...I'm slowly learning .

I re-checked the resistance on my 454 IAC and I got 48 ohms across A-B and C-D. I also verified there is infinite resistance between A-C and B-D. Out of curiousity, I checked the resistance on my 305 IAC and it was 49 ohms on A-B and C-D...it's starting to look like there's nothing wrong with my 454 IAC.

I then wired up my 305 IAC (see pic) and was pleased to see that the IAC reset procedure worked like a charm using it. The 305 IAC started clicking and was completely shut once I jumpered ALDL pins A & B. I forgot to actually run the engine with the 305 IAC hooked-up, but I think the fact that it reset indicates there's nothing wrong with the signal being sent to the IAC by the ECM. Let me know if it is necessary to go through that routine and I will.

Next, I proceeded to wire up my 454 IAC in all eight possible pinouts, assuming that A-B and C-D have to be the same color...I mistakenly thought there were 16, but then realized I was wrong when I laid it out in Excel. Here are all the pinouts I tried:

1 2 3 4
A grn/wht grn/wht grn/blk grn/blk
B grn/blk grn/blk grn/wht grn/wht
C blu/wht blu/blk blu/wht blu/blk
D blu/blk blu/wht blu/blk blu/wht

5 6 7 8
A blu/wht blu/blk blu/wht blu/blk
B blu/blk blu/wht blu/blk blu/wht
C grn/wht grn/wht grn/blk grn/blk
D grn/blk grn/blk grn/wht grn/wht

Several of these were pinouts I had already tried, but I figured it was better to verify everything again. Now that my fingertips are numb from tying wires together, I now know that my problem cannot be with the pinout. Not a single pinout worked when I attempted the IAC reset procedure.

Lastly, I checked what seemed like the only other possible problem source...the IAC connector itself. However, I found zero resistance between each wire and its respective female connector location.

The only thing I can figure is that the resistance check on the IAC does not necessarily indicate that it is in fine working order. I located a Chevy dealership with an IAC tester today and I'll be stopping by tomorrow afternoon for them to check it out.

Meanwhile...does anyone have any other ideas as to something I should try?

Brent

iTrader: (1)

Aye. The motor/pintle might be frozen.

I sure wish I had thought of that earlier. Would have saved you some time.

You know what, if that IAC tests good, I will eat my shoes and post the pics.

Ronny

iTrader: (1)

I feel your pain! i too struggled last spring trying to dial in my combo. i see in the thread the 1995 GM 7.4L TB. i have one to be installed 4/04. couple things. first off the base gasket given to me by Howell for my 'adapter" appears not to fit the 1995 application. the IAC path/tunnel i will assume needs gasket sealing completely around it. my gasket takes short cut from mounting bolt to mounting bolt allowing no seal in iac's path to venturi as well as a lack of seal into venturi bores besides seperate from IAC issue. i think that is a major vac leak. howell must mave give a more "commom" gasket in kit. also i too cannot find the specs on the injectors17104288 . i asked GM dealer to look up FP only and call me and they did not respond. yet. i will guess they are @ 26 lbs and 68 lbs. this would be consistent with 90 lbs at 12 lbs FP in other older 7.4L.. i plan on removing them (68) since my 85 pump is good to 19 lbs and add exernal FP regulator and cap off the stock GM reg and monitor with my existing gauge. good thing i did not just swap in the 90 lbs at 26 lbs with stock 7.4L spring.

Bulldog92

iTrader: (1)

Well, Brent...keep your shoes on, the IAC is TOAST per Mr. Goodwrench

I now have a new IAC, P/N 17113099 headed my way ever-so-slowly from gmpartsdirect.com...they're $40 cheaper than the local GM dealer. Based on past experience, I don't think I'll see it until the end of next week.

Ronny, you bring up an interesting point...I never even thought to check and see if the gasket I bought for my 454 TBI was properly cut so that it would seal off what it should. I'll be sure to check that if I am still having high-idle problems with the new IAC. Oh, and I ran into the same roadblock with every GM dealer in town regarding trying to cross-reference our 17104288 (apparently a Bosch part #) injector with a specific flow rating. Do you really think that injector is only 68 pph @ 26 psi? If that's the case, I'm definitely going to either have to swap them for 90 pph @ 12 psi injectors or go with the Walbro 255 pump and jack up my fuel pressure to some ungodly (in TBI world, anyway) level.

Well, now I get to wait on the UPS man. I'll do some data logging when I get the new IAC installed, but I imagine that I'm going to end up having to bump my BPC back up as well as reinstall the stiffer 454 pressure regulator spring so that I can squeeze my factory fuel pump for 15 psi (I hope, anyway). Of course, I'll have to tweak the VE table as well. Updates to follow next week...

Edit: I forgot to mention that the guy at the Chevy dealership also confirmed that the '95 454 IAC has an identical pinout to the '92 305 IAC...at least I know what to try first now

Brent

iTrader: (1)

That is certainly good news... for me anyway.

I suspect 17104288 is an internal GM part #. Alot of GM stuff has these type numbers stamped into them and they can't be pulled up on the dealerships computer.

One thing is for certain, you will need approx 30 psi of fuel pressure for those injectors to flow enough for 240hp which is what the '95 454 is rated at. They probably flow 75-80lbs/hr @ 30psi.

Since your engine has roughly 90 hp more, you will need an additional 20 psi to fuel your 330hp engine.

50 psi may cause gasket trouble, etc....

The other option, which is more desireable IMHO, is to do it the same way GM did on their 338hp HT502 TBI kit. Use the 17112560 454 injectors and a 19-20 psi regulator.

Either way you'll need to install a high pressure fuel pump. This cannot be avoided. The stock pump just won't move enough volume for 330hp at the required pressures.

If you loathe the idea of dropping your fuel tank you could probably install an inline booster pump like the centrifigal supercharged guys do.

Bulldog92

iTrader: (1)

Oh, no.... ...please don't tell me I'm gonna have to sink MORE money into this thing. This swap is approaching $6K way too fast.

I see what you're saying about the injectors being inadequate (assuming that we're all correct in assuming that they are rated @ approx. 30 psi), but one thing confuses me. Even with my low fuel pressure, weaker 305 fuel regulator spring, and BPC set @ 100, RBob interpreted my O2 voltages as being rich @ higher rpms:

That makes me think that I will be able to work with my existing combo and tune it so that I get my BLMs close to 128 across the board...but maybe I'm just in dreamland :lala:

I like the inline booster pump idea (if I end up needing it) as opposed to dropping the tank (which I'd never do after my gas spill fiasco). Do you have any supplier info/pricing on one? I checked the pricing on the 17112560 injectors and they're $200/pair on gmpartsdirect.com. Man, I hope I can stop spending money on this car one day and actually just drive the thing.

Brent

iTrader: (1)

If you do some searching I'm sure guys like Cruzinperformance or Lindertech have reconditioned 17112560's for sale.

You could recoup some dollars by selling the L03 TBI and the 95' 454 injectors on ebay.

Take a look at 20040125_040550_LOG.xls

See how the BLM is at 150 @ 2000rpm? Thats very lean.

I guarantee it will be horribly lean at WOT with those 17104288 injectors even at 15psi.

If you want to do some experimenting while you are waiting for your IAC, try burning a bone stock bin of the AXWK or whatever that is you are running. That should result in better BLMs.

You could also (since you know its junk) pull the IAC pintle out 1" from the body and reinstall it. This should allow it to idle down and will tell you if your gasket is not sealing like ronney mentions.