kevm14

My girlfriend's dad has an 83 C10 that had a worn out 250. He rebuilt a 292 from a 68 vintage HD truck and we've basically got it running initially. Still need to break in the cam, rings, get the timing closer, and fully weld the exhaust.

Here's MY problem: it's got a 1 barrel carb. We can't have that

So I've got him interested in doing a GM TBI conversion (something I know has been done before, but not that often), probably using the rochester 220 variety used on the V6 and SBCs (like one of the cars in my sig) partnered with one of the off the shelf 4 bbl intakes using a TBI adapter. I doubt this thing is much above the 200hp level (if at all) so I know it'll not be an airflow restriction in the least. I also want the ECM to control spark. Right now he's using the old 250's distributor, which looks to be a regular HEI (vacuum and mech SA).

I had a few questions for the board. In our search for a donar vehicle or ECM/TBI/harness, should we limit our findings to only 4.3 V6 vehicles? I was thinking an 88 R20 with a 4.3 V6 would be pretty good since everything would be layed out for the older body style, plus EFI. Then again, layout doesn't matter much since we wouldn't retain much of the donar vehicle's harness (there isn't much in this engine bay). Do all ECMs have removable calpaks? Should we look for ECMs with memcals only? Or not worry about that and just stick to V6s? I just don't want to tell him to pass up an L03 truck if all the ECM needs is an easy-to-obtain calpak to make it think it's running a V6.

This is where I call for Chevy inline 6 knowledge: what do we do with the dist? Is there a late model dist that used electronic spark advance (I think they ran the 292 until 88 or so)? Can the EFI dist electronics be installed into the older HEI dist? Can it run a V6 dist stock/with mods/at all?

Thanks, and mods let me know if this is the wrong forum or inappropriate entirely...

Z69

Just use the HEI internals minus the module.
Then make up a mount for a 7 pin efi module and run the
trigger wires out to it. Make sure you twist them.
Then weld up the mech adv and bolt down the vac adv. ( or leave it on to mess with people) Just pop the diaphragm and silcone up the canister hole.
If it's a large cap, you could mount a 7 pin inside probably.


More too it, but not a lot.

You could be stealthy and mount port injectors on the bottom of the intake. And run a carb for a TB with the venturi's knocked out and plugged.

kevm14

That stealthy idea is pretty cool. He would like that. But right now I guess I want to focus on getting it running before worrying about a stealthily detailed engine bay.

What is a 7-pin EFI module?

What's really required? Pickup coil, ICM, coil, ESC (is this for knock sensing or general use)...?

PhLaXuS

I believe the 305 TBI models were the only 3rd gen engine to use the external ESC module -- all the others are built in to the ECM. The engine will run w/o the ESC module, but performance and economy will suck, so don't even try it. If you disconnect the ESC module on an otherwise well operating engine, the ECM will pull all timing advance as a safety measure. Same goes if you disconnect the knock sensor itself. I'm pretty sure the ESC module outputs a +8 to +10VDC signal on the EST RETARD line when no knock is occurring. Attached is a schematic of the 305 TBI ESC.

PhLaXuS

And here's the spark timing circuit...

kevm14

I have the factory service manual for my Caprice, so I could probably find the equivalant diagrams.

Also, my car also has an external ESC (5-pin). I disconnected it once thinking that's how you set the timing, and the car wouldn't start. Where does that 1 wire go that we all disconnect to set the base advance?

Z69

Check out the MegaSquirt site for more HEI info.

kevm14

Oh, I see. You were advocating the use of a Megasquirt system instead of using a GM ECM. For now, my plan is to use a GM ECM with the U-TBI code and 17 frames/sec data logging. Maybe it's time to study my FSM.

EDIT: Ok I'm on the Megasquirt site. Reading this http://www.megasquirt.info/ms2/Ignition.htm .
Seems pretty informative. But I'm still confused. In the module section, they're using terminology like "7-pin" which is what you used. Is this the same as the ICM? If so, what is that 5-pin ESC in my Caprice? Just for knock sensing or something additional? I know my car didn't start with it unplugged...

PhLaXuS

The 5-wire is the ESC (Electronic Spark Control) module. The 7-wire is the ICM (Ignition Control Module). You can see the 7 wires in the schematic I posted above. It includes all the wires in/out of the EST Distributor rectangle...minus one black wire which runs from the coil to the distributor rotor.

On the thirdgen, the SET TIMING disconnect wire runs very close to the A/C dryer canister in the engine compartment near the firewall. It's a brown wire, I believe, and briefly comes out of a thick run of split-loom tubing. It's got a black 1-wire connector. Simply unplug it and set the timing. Be sure to plug it back in when you're done. It's amazing how many people forget that step.

kevm14

Hey check this out: 7-1/2 years later, this same truck with a new 292 rebuild is currently running with GM TBI! Hopefully some folks will appreciate a new project on the boards.

I wasn't able to participate in the initial conversion but here's what I know:
- He ran the ICM externally as mentioned
- 4bbl intake with TBI adapter (first one was plastic and sucked, the second is a Holley I think)
- Hotter than stock cam (I have the specs)
- Head work (fairly typical of warmed up inline 6, as I understand it)
- Higher than stock CR (maybe 9.0:1-ish)
- Bored 0.030" over (296cid or so)
- Base donor vehicle was a 92 G20 conversion van ($99 mask ECM)
- Currently running with the '7747 from a 90 Blazer L05
- Knock sensor from the L05 van is installed (I think he has the 92 G20 ESC at the moment)
- O2 from the van but he is upgrading to the AFS-74 at my request
- No VSS currently (trans is a heavy cast iron 4-speed manual) but plans to upgrade to the van's 700R4 and 3.42 axle once we get the engine running right
- 87 octane
- 180° stat

Tuning VE is self-explanatory. Even AE I can handle using SOTP methods. Though, I would love to try the EBL on this project for a variety of reasons. Anyway, I guess my main question is spark advance. Believe it or not, he was actually able to drive his truck an hour on the highway with the stock van ECM, though it had plenty of drivability issues.

I suspected that these heads would require quite a bit more total timing than the L05 swirl port heads (I assume the truck L05 runs those like my Caprice). But I really have no idea how much. 38° all in? Maybe even more? Also given the cam, I expect to need to bring in timing sooner than before, and probably more at part throttle, also. Using the L05 as the baseline, though, makes it hard. I did try to extrapolate a timing table from a specification he found in a manual regarding the centrifugal and vacuum advance. I think the vacuum advance was connected to ported so I may need to re-do my numbers.

The knock sensor does seem to be working and we haven't heard pinging yet. Knock counts almost never register while driving, which is good.

Base advance seems inadequate as the startup isn't very clean. This should come as no surprise since base advance is currently around 1° BTDC, stock was 8° and there's a cam...it probably wants at least 10°.

I've only spent a few hours tuning it so far and it's improved a LOT. Again, I started from the 90 Blazer 7747 and cal. Here's a brief run-down of what I've done so far:

- Set BPW to 148 (my best attempt at the right value - I think these are 61 lb/hr injectors and they are running about 14psi)
- Set the manual flag (not sure what this does)
- Disabled the irrelevant DTCs
- Tried to disable highway mode (max speed to enable was only 80 but with no VSS this won't be an issue, for now)
- Disable EGR (no EGR in this application)
- Set number of cylinders to 6 (not sure what this does, either)
- A bunch of VE tuning
- Added 25% TPS AE
- Added 10% MAP AE
- Raised idle
- Tried to get rid of the open loop idle crap but I still saw OL idle sometimes, which is why I had him order an AFS-74
- A bunch of spark advance work (7° more at 2800+, then increasing even more at lower rpm, with as much as 11° more from 400-1800)

The spark advance made the biggest difference by far. The worst drivability issue was a nasty intake pop on heavy dTPS from low rpm. The spark advance (not the VE or AE) turned that into a stumble, which is an improvement. But I just have no clue what this thing really wants. By the way, he said the original 1bbl and mechanical dist setup did NOT pop like that. I guess I'll keep blindly playing around and see how it progresses. I don't even know if these heads are detonation limited; it's a different beast than the SBC.

One more question: does anyone see any reason to run the $99 mask ECM ('299) from the 92 van in place of the '7747? Looking at the Tunercat definition files, the '7747 is really better suited for this, imo. EBL may come sometime later but I know I can do better even with my antiquated EPROM burning equipment and sssssllllloooowwww ALDL data rate. And no WB O2....

This ought to do as a first post on this project, anyway.

kevm14

This 7747 is starting to **** me off...lots of idle issues. I.e. when adjusting the throttle stop more open, the IAC counts don't come down, and the RPMs increase....switching to the 99 mask ECM ('299) IAC comes down to 0 steps.

I think I read somewhere (here) that the idle routines in the 7747 leave a lot to be desired. Probably going to upgrade to EBL and a WB, which will be like a breath of fresh air, to say the least.

Ronny

iTrader: (1)

What do the IAC counts read at idle fully heat sunk with 7747?

Are you sure IAC is functional with 7747? Key on engine off does it cycle looking at pindle down the TB venturi?

I would expect the 7747 to work OK. I do see a cam and head work but my car had same maybe much more and 7747 ran it OK. After all it is a truck

kevm14

One of the issues is they seem to be all over the place. In the past, I was able to set the throttle stop so it was ~15 steps at idle. Then you'd drive the truck, get back and the idle would be a little high. Sure enough, IAC steps at 0. So I'd readjust the throttle stop to bring it back to 15. Then we'd start up the truck later and at hot idle in closed loop it would be reading like 90 steps at the same ~700rpm.

Another issue is, it has a really poor idle flare upon startup. Not sure what to expect with this ECM, but we did test the idle RPM at a park position (which I raised to 180) and it was only like 1200rpm. My L05 Caprice does like 1600rpm at 160 steps. So something isn't right but we haven't been able to figure it out aside from maybe some slight bushing wear on the throttle shaft. But that doesn't explain all the symptoms.

One thing that's occurring right now is we can't actually get the steps to bring the idle down at all, no matter how open the throttle is. I figured it was coming out of idle mode, so I had him ignition cycle the truck to reset the closed throttle TPS voltage. No change. Then he read that the 7747 requires a TPS adjustment and maybe there's a hard coded max volts for idle mode. So he opened the throttle, and dialed back the TPS until it read ~0.55V, and it still refused to go below like 65 steps (though I thought it was before). Next thing he tried was plugging in the stock '299 $99 mask ECM from the 92 L05 G20 van. It happily closed the IAC down to 0 steps. I do believe the inconsistent idle behavior was present with the $99 mask ECM, so maybe that portion is something mechanical. The wiring is good. We have two IACs but one seems to have more issues than the other...

Seems like there are a multitude of problems. I don't want to throw a $50 IAC at it but I guess if it would help? We can try the ALDL A-B trick to get the IAC to go to 0, then remove it and turn the key on and watch it open up to park. I guess that would prove something.

Does anyone know if the 7747 has a hard coded max volts for idle? Even so, when he brought the volts into a range that should clearly register for idle, it still refused to adjust the idle down any further than 65 steps...it's very frustrating and of course the 7747 data stream is so friggen lousy....I don't think it shows target idle RPM or TPS % like my '6965 does. That's why I think it's EBL time. Maybe I'd have better luck screwing around with the '299 ECM but I'm not sure....

I realize the 7747 was the original hacked C3 ECM, but honestly I have no idea why people like it so much. Unless I am blind, it seems like the idle table only goes down to 55°C. What the heck is that nonsense all about? I've had a much better experience with the '6965 in my Caprice.

kevm14

Aside from my 7747 complaints, I did have some luck with overall tuning, which I thought I would share.

I've burned 237 chips for my Caprice since Jan 2003, which is hilarious, since I've never had the valve covers off. Anyway, I know my way around Tunercat, but this was my first experience with the '7747. There are some clear differences, even though I know it's the same basic ECM. Evidently they tweaked each P/N for different applications, since they had to remove some things to add other features when needed. That much is clear.

So on the spark advance, I roughed in a curve that starts at about 11d @ 600rpm and 100kPa and ends up at 32d by 3600rpm with a very modest extender. I left the PE SA adder (5d from 2000+). It idles with 30d, though I may reduce that a bit to give the engine some torque headroom for idle SA corrections (assuming the 7747 even does that).

Without a WB, it's hard to estimate the AFR but I feel like this SA curve is alright until we get an idea on fueling. Another reason I want to go to EBL is so I can have an idea about injector DC. It's at 14psi with the 61pph L05 injectors and that MAY be enough fuel, but I have no clue. This engine is never going to see over 5000rpm. Looking at my VE table, I have a HUGE jump between 90 and 100kPa which is most likely incorrect. With that large jump, I am looking at up to 105% VE from 2000rpm and up at 100kPa. I am using 148 for the BPC which I calculated to be correct for a 296cid inline 6 with 61pph @ 14psi. I may need to lower it but if I can't see the DC, then I am blind. Without a WB, it's hopeless.

VE learns improved drivability, though redoing the SA to mimic the kind of curve I intuitively expect this engine to want helped a lot. Still no pinging, and the only knock counts I've seen are from cranking, or grinding the trans.

I worked really hard on AE, which is another reason I felt the 7747 limiting my abilities. It would stumble pretty bad on a hard throttle shove. Originally it was popping through the intake but redoing the SA actually turned that into just a nasty stumble. I tried reducing AE. I tried increasing it. Again, without EBL/WB, I am damn near blind. Amazing people were able to get AE right with these ancient ECMs 10+ years ago.

Eventually, I used my butt dyno to tell me what the engine wanted. The intake has no plenum and it's non-heated. So I felt it needed a heavier but shorter shot. I used the filters to deliver a higher PW but end it sooner. Miraculously, that helped a LOT. Now the stumble remains only in 4th gear if you romp on it hard. In the lower gears, it's about gone. So that was rewarding.

Another thing it needed was leaner crank AFR when warm. It was loading up and running rough. He tells me it needs throttle when cranking cold so clearly there is work to be done on that, too.

The AFS-74 helped a lot with staying in closed loop at idle, though I don't completely trust the 7747 because for whatever reason, the stock trucks needed a richer open loop idle (my Caprice didn't). So I never feel like I can fully disable some of that stuff. Then there's PE delay, another thing my Caprice never had or needed. Again, I've tried to turn this stuff off but I feel like it's sort of worked into the code and some of the constant ranges don't go high enough sometimes to feel like I am really disabling it.

Next step I think is EBL + WB, and somehow we will have to figure out this IAC situation. Shouldn't a ~296cid I6 idle at 1600rpm or greater with the IAC in park position? I would surely think so.

What does the stoich AFR constant do? If I wanted to compensate for E10 or whatever, don't I need to change the O2 switching thresholds? Seems like I need a WB, yet again.

EDIT: I just remembered the NB O2 is a lambda sensor, right? So it will always switch around stoich, regardless of fuel, correct?

Ronny

iTrader: (1)

Not sure if this is of any benefit but jump AB as you said then disconnect and run on TSS. I wonder if idle RPM would vary much IF coolant is steady and IAT is steady. I ran for 2 seasons with no IAC. I have a manual trans.

Are all IACs the same size. IOW is your passage way too large? You arent using a 7.4L TB are you?

I am running thresholds 10% rich. My commanded is 14.1. I run E10. My WB shows lambda at 1.0. E10 is 14.13 I think.

kevm14

No it's a stock 350 TBI.

Yeah I spaced on the NB O2. Since it's based on lambda, it'll always switch around stoich. The O2 switching thresholds are for other factors, such as valve overlap, AIR injection or what have you.

EagleMark

The Stoich AFR or Desired AFR should be set to 14.13 if E fuel is being used and will help VE Fueling calculation avoid BLM/LTFT trying to compensate for the difference in AFR of Gasoline to Gas with E.

Also drop PE AFR to 11.9

PE delay can be set to 0.

Watch all the spark adders if you run an aggressive spark table! PE spark add, RPM Slope Add... then if you added a bunch of spark to idle take some out of Crank Spark table.

Lots of your Closed Loop idle can be the bin you started with. Use ASDU and move your tables over. ASDU is a factory CL Idle bin.

No need to check manual, unless it is one? If so use ASDW which is 5.7L manual.

Don't worry about the cubic inch difference, just set BPW.

Don't change any Highway Lean Cruise Settings unless you have applied the patch! I think this is what is causing you IAC issue? Have to ask RBob what you changed if the lean cruise patch was not applied?

Do not use 10k on cable for data.

10% and 25% AE is nothing. Start with 100%...

For the high idle when cold and start up flare you need to Park/Neutral wire hooked up. If not idle is always pretty flat and off of Desired Idle tables.

If IAC is parked/Closed and your idling at 1600 RPM? You have a vacuum leak?

HTH!

kevm14

Does the stoich AFR constant really affect closed loop/BLMs? I don't think the BLM can do anything but keep the O2 switching around lambda 1, regardless of that setting. But then, what does that setting actually do?

Yeah that makes sense. It's commanding upper 12s now, but we need to get a WB installed because this blind tuning stuff is no good.


I think it is but since my '6965 has no PE delay, I never fully trust whether maxing or mining out certain constants really disables stuff.

Not sure if I've seen crank spark in Tunercat. I thought crank spark was just base timing. I do think these heads need quite a bit of SA, though. He did find one wiring issue: the battery 12V connections weren't connected properly. So the ECM was resetting each ignition cycle. There isn't a whole lot of learning these do, but he says the startup idle flare seems more normal now. Go figure. Still won't get the IAC steps below about 65, though.

Ah. I guess this is a little too late, assuming we order EBL soon like I plan to. Where can I get my hands on these calibrations? I THINK I got it set right, though, as it stays in CL idle after the upgrade to AFS-74.

Yes, heavy duty 4-speed manual. Later on, he'll do the 700R4 and 3.42 axle from the 92 G20. But I want to get the tune dialed in pretty well first, since I have the advantage of the manual.

I didn't touch lean cruise...I don't think his setup will do well with it. I doubt the heads mix well enough to make it work right.


When I got the magic combination of more PW but more filter (less duration) that really seemed to be going in the right direction. Then we ran out of time. Not sure how much more 7747 tuning I'll be doing, if we order EBL soon. The truck lives an hour 45 away from me...

I think it is in park/neutral all the time, based on the scantool.

At an IAC position of 180, his idle was no more than 1200, maybe a bit less. I was contrasting that to my Caprice which, at an IAC of 160, is like 1600rpm. I then suggested that this could be related to the pitiful startup idle flare. Not sure what's happening here.

kevm14

Update: He says the startup idle flare is definitely more pronounced after getting the 12V connections correct (which presumably allows the ECM to hold any IAC position learning from the previous ignition cycle). However, the strange behavior continues. The good news is, it seems consistent. Here is the behavior:

If you start the truck, the IAC seems to hit no less than about 65 steps, and the idle is thus too high. Then he drives around for a while, comes back, and the idle will settle down to the commanded RPM. If he shuts it off and restarts, the same thing happens again. What is going on?

Question: What does the 7747 have for NVRAM learning that holds over to the next ignition cycle? Is it just IAC stuff? I assume BLMs reset (unlike the newer computers).

EagleMark

It does store BLM, but more importantly without the power you were loosing the IAC Park position and key on reset etc...

I think your issue was self made in your first post, you did say you disabled highway lean cruise by changing MPH?

There is no highway lean cruise in the $42 bins! It is a patch and moves some code around. You made a change to highway lean cruise without the patch so who knows what you changed? Your seeing a IAC park position of 180? All $42 bins I know of are 145? Something is wrong? Start with fresh bin!

Also what bin did you start with? Many floating around are GM superseded. Also the bin most would start with for a six cylinder is a V6, I've only found one that is Sync fueling and Async fueling absolutely sucks in a I6 conversion do to wet intake and the LONG intake runners!

Stoich setting is first part of Closed Loop fueling calculation. Say your stock motor with stock bin was perfect 128 BLM readings when fuel was 14.68 = non ethonol gas. Well now you run E10 and BLM are 136...

I should have said Coolant Compensate Spark Advance.

Look at your "IAC position vs Park position" table? This table really varies in $42 bins and lowering can help idle. Here's what I like:
But more importantly you only get full IAC control in gear, not park neutral.

Min Air setting on throttle blades is also an issue. The way I get these down is by watching IAC counts at end of a drive/datalog in gear! shoot for 20, then when you go to neutral IAC counts will drop to 5 or lower? I always like a couple.

If higher then 20? Turn vehicle off, just turn in throttle blade screw 1/4 turn. Restart, TPS% is reset to 0 on each key on. The .54 volt is not that important as long as it's not over 1 volt is what I read here long time ago. I've never had any issues or had one change more then .75 and left it.

http://www.gearhead-efi.com/Fuel-Inj...Information-42

HTH!

kevm14

It stores BLM??? I thought the C3 had no provisions to store fuel trims between ignition cycles, unlike the 8051 LT1 PCMs...

Tunercat shows some lean cruise stuff, though highway SA is all zeroed out. I made sure I disabled everything I could find to keep it from enabling, but I guess I forgot the $42 ECM never had it from the factory. I didn't apply any patch. I started with ASDV from a 90 Blazer L05.

Yes, 145 was stock. I changed it to 180 in an effort to get more idle flare out of it, and overall make sure the IAC circuit was flowing air correctly. It seems to be working better now that the ECM can retain power when the ignition is off, for whatever reason.

ASDV. Starting with a 4.3 V6 manual (and CL idle if that exists) would be great, so maybe I'll see if I can find something like that. Your comment about async fueling makes me think that EBL is going to make a HUGE difference with this truck. Do you know which has sync fueling from the factory? Can I convert ASDV to sync only? I know about the sync to async PW thresholds but not sure what else I might need to change.

Hmm, so you're saying the stoich setting will change what BLM is reported for a lambda = 1 mixture. That makes sense. So tuning for 128 with a stoich = 14.7 as it is now means that my VE isn't accurate (may explain why I am running over 100% at this BPC). I will be sure to change that, thanks.

Coolant comp spark is doing nothing at operating temperatures. I did look at that. Though he did just change to a 195° stat so I need to take another peek.

Here's how this one is setup currently:
Looks like I raised them, maybe in another effort to get a proper startup flare. Maybe I should lower them. Though if it goes into proper idle control, I don't see why this table matters. If I understand this table, it is used to dial the IAC into a range when the ECM is NOT controlling the idle. But then there's the throttle follower, VSS follower (no VSS yet), and any learned steps stuff...

Well it's a manual. Any idea why it doesn't seem to want to control the idle upon initial startup but it WILL drop the idle after driving for a while? I believe it is in CL in both cases. The rpm just hangs and it leaves the IAC open. Very strange but there's probably a reason, I just don't know it yet. I agree with making sure the lowest possible IAC position is about 5, so it's just a matter of finding the right min air setting.

What is the range for the 7747? Is it 0.3 to 0.8V? And is there a range above where the key on TPS was that is considered no longer closed throttle? Like 0.3V above key on TPS volts = off idle? That would help give me some idea how tolerant the ECM is to this stuff. Yet another reason I look forward to EBL, so I can see what the hell is going on.


Thanks! I will take a look.

EagleMark

Sounds like your an EBL user and there's no way I can talk you out of it or any reason! It's excellent! Just trying to help you with what you have.

At the link provided is some excellent TunerPro XDF for bin changes and ADX for data logs for $42 which may help.

Has nothing to do with volts, it's all set up to % in bin.

Manual trans vehicles and bins are always in gear, no P/N switch so the only high idle when cold is in "Desired Idle table" which changes do to CTS.

Right, stock bin will show all 0 in highway SA and although TunerCat and TunerPro will show paremeters for highway lean cruise, none should be touched without the patch! In TunerCat I beleive the HLC Patch is under File, Patches.

Don't have it? Never heard of it? Can't find any record of it? So I have no way to see if it was a Sync bin or CL idle? If it really is ASDV I'd like a clean stock read of bin please!

The only V6 manual bin I know of that is Sync fueling is APAA which would be a good start... that said I always build bins and tune from ASDU for auto or ASDW for manual and make them six cylinder...


That's something I have never had to change? There's tons of reasons the IAC is working better now that ECM has proper power, read RBob IAC operation article for more understanding!
http://www.gearhead-efi.com/Fuel-Inj...pdated-12-4-00

Right! But you added all sorts of spark to main table and with additional spark from this table when cold can add to TOO MUCH! Same thing for RPM slope Spark added and PE spark added, if you already have all the spark a motor can take in main spark table? Then these adders can cause havoc!

Well sort of... but a bigger issue is you also need to look at VE1 and VE2 adder table. If your already over 100% in VE1 and have not factored VE2 then your already way short of fuel and BPW is not going to help. You need bigger injectors or more fuel pressure!

HTH!

kevm14

I don't have it yet, but I've wanted it since it came out, and before that, I was tempted by the Lockers hack...never did that either. This seems like a great opportunity to try EBL. I do appreciate you helping with the 7747 that I've been working with. It seems I made a few mistakes in the beginning that I may be paying for right now, mainly in starting with the 90 Blazer L05 auto cal.

Right, so I guess it's just max % for idle mode. Problem is, the 7747 data stream doesn't seem to output true TPS %. WinALDL shows a %, but it's pseudo % based on some TPS min and max volts, and it's not good enough to use, imo.

His is in gear, so I was mistaken on that. I was annoyed that the CTS vs idle RPM table doesn't go very cold, and I assume it uses the value at 55°C for anything colder than that.

All I changed was the min speed for highway mode (set to ~79mph). I can change back to stock 30mph but I'm not sure it really matters.

Sure, I will upload using my tuning laptop.

Pic here: http://sdrv.ms/15kDWkv

I did set the num cylinders to 6. Not sure what else is inherently different about a 6 cylinder cal.

I was trying to get the startup to flare better, in conjunction with the higher IAC steps vs CTS table.

Agreed. Though I think these heads need a lot of spark advance. They're old school and were also ported, and I suspect that the porting focused more on overall airflow not so much subtleties like low lift flow, velocity, swirl, etc.

I am only over 100% in a few areas, and only if you add VE1 and VE2. Given that I have the stoich setting wrong, that could drop me back below 100%. That makes sense as if it thinks stoich is 14.7, and I need more fuel because stoich is actually 14.1, then it would read as higher VE (false). That is assuming the gas is really E10. I think it can be "up to" 10% ethanol. Anyone have a clue for what southern New England might be for ethanol content (CT, RI, etc.)?

But I have no clue if I am maxed on my DC right now. I have seen conflicting advice before where some folks swear if your BPC is set right, and your VE is over 100%, you're just out of injector. Other folks say you may only need a BPC adjustment, because you may not be out of DC (I think RBob said this). Then there's the complication of DC and RPM with the TBI fueling schedule, which means not only does your DC shorten with RPM (as with any engine) but the max DC you want to run actually decreases at higher rpm. Fortunately, this will stay within the range of a stock TBI V8 so that should be alright, if I stick to 85% and below. But again, no clue what it is now.

EDIT: Here is the ASDV from the 90 Blazer L05 auto. Also attached my latest bin.

RBob

iTrader: (1)

This is normal in the '7747 ECMs. In the tuning Guide Book up above there is a IAC Logic writeup. IAC control in the '7747 ECM is rudimentary (read: bad).

That is one area that was completely rewritten in/for the EBL products.

RBob.

RBob

iTrader: (1)

Ugh, the Tuning Guide Book sticky is on the DIY_PROM board, not this one...

RBob.

kevm14

These bins are looking like good candidates. Any suggestions?

APAB-$42-4.3-Manual.bin (4.0 KB, 54 views)
AKSN 88 C-K Truck 4.3TBI 5 speed california.BIN (4.0 KB, 23 views)
AKSP 88 M-van 4.3TBI 5 speed with 3.08 or 3.42 gears.BIN (4.0 KB, 21 views)
APAA 90 S-T Truck 4.3TBI 5 speed with 3.08 gears.BIN (4.0 KB, 16 views)
APAB 90 S-T Truck 4.3TBI 5 speed with 3.42 gears.bin (4.0 KB, 24 views)
AWDN 88 C-1500 4.3TBI 4 speed manual.BIN (4.0 KB, 22 views)

I can take a look at them one by one but I'm not sure what makes one a better candidate than another for my application. Sync-only fuel? CL idle?

RBob

iTrader: (1)

ASDU, the way GM prints the label makes it easy to mistake a V for a U.

RBob.

RBob

iTrader: (1)

Spark advance, L03 & L05 engines with the swirl port heads have very little SA. Makes a non-swirl port headed engine lazy and less fuel efficient.

RBob.

kevm14

RBob,

Is this thread in the wrong forum? I thought it was neat to continue it after my OP back in early 2006. I guess originally it was about converting the truck but now it's mostly just tuning.

Your comment about the 7747 idle does sort of solidify my thoughts about upgrading to EBL. Though the van $99 seems to do a better job with idle, but I don't have a definition file for Tunercat and I'd rather just man up and upgrade to EBL.

kevm14

Yup, sure does. Needed more base advance to start (10d may be too much now - stock 292 was 8 and this has a cam but higher compression, so staying at 8d may make some sense). Also I added a TON everywhere else.

EagleMark

D'oh! I should have known that was ASDU...

It's a great start, just don't change any highway lean cruise parameters if you have not applied the patch!

You have ASDU! Which is always a good start. Sync fuel and CL idle! Change to six cylinder and start tuning.

If you really must have the flare up at start then run ECM pin B10 to a toggle switch and ground it. Then turn off/no ground in gear for full IAC control.

IIRC idle is less then 1.17%. TPS% is always calculated or set to 0% when key on. Good reason to never have your foot on gas pedal when turning key on. Your worrying about something that's not an issue.

Most states have labels that say up to 10%. The only way to know for sure is with an ethonol test kit. Our fuel does not change for summer or winter and I have seen between 8-11%. It's all splitting hairs at this point, just use 14.13. But when you re open in some bins it's adjusted to 14.10. Then forget it.

That's all about right. A BPW setting of 134 will be running out of Injector Duty Cycle at around 3500 RPM. Should not really be an issue with a six conversion. When you enter PE it changes the AFR to richer and even if IDC is over 100% your still not lean to a point. Wide Band O2 sensor is only way to tell in PE.

Just FYI some stock bins are over 100% when VE1 and VE2 are added... GM messed up...

At the link I gave earlier for TunerPRo XDF and ADX there are hacks to see Injector Duty Cycle and Spark advance as well as true TPS%, but the TPS% is for testing only!!! It disables Knock counts!!! = no knock retard!!!

This is why I was warning you about all the other Spark Advance Adders!

kevm14

I think I had to mess with some parameters to get CL idle, but then again, maybe it was just the AFS-74 that finally let that work. ASDU is sync-only fuel? Other than the async-sync PW thresholds, what makes a cal sync-only? I'm foggy on this. Do you think I need to start with a manual trans bin? Or a 4.3 V6 bin? I set the manual flag and disabled the relevant DTCs...if all is good, then I guess I got lucky and started with a decent baseline.

I wouldn't say I must have it, just that the distinct lack of it suggested IAC issues. After giving the ECM 12V power after ignition off, it seems to be behaving as a 7747 should, which as as much as I can ask for obviously. B10 must be the park/neutral sw input...

Well, RBob said the behavior I noticed was normal, so evidently you're right - nothing more I can do here. Out of curiosity, if you crank with the throttle cracked, does it re-zero when you let off or is that whole ignition cycle whacked from a TPS % standpoint?

Gotcha. Sounds like if we have "up to 10%" then stoich will be closer to 14.1 than it will be to 14.7. Set it and forget it.


I have the BPC set to 148 currently, based on a 296cid 6 cylinder w/ 61pph injectors @ 14psi. Does this sound like the right ballpark? Do you think the injectors are going static at 100% VE around 2000-3600rpm?

You know what - they should have just allowed the code to work with over 100% VE. I think it would make our lives easier in some ways. I mean I think we already accept that the VE in those tables doesn't directly translate exactly to actual volumetric efficiency. But then moving the BPC up accomplishes the same thing, I suppose. I think we're going to order EBL + WB this weekend. Though we may tinker with this 7747 just to have a backup ECM, as well as because I think it has a little more to give, in spite of my initial thoughts.

Plus this build has inspired me to do something with my Caprice, even though at one point I was sure I was either going to do nothing at all, or some LQ4-based build. For those of us still using TBI, I think we derive pleasure from getting so much from such a simple and lambasted system.

Thanks again for your input and interest.

RBob

iTrader: (1)

A sync only calibration would have the go-to-async short PW parameters set to zero. That way the ECM doesn't go async when the PW gets small. Although, AE is still async.

It can be helpful to start with a stick calibration. There are some differences in SA and IAC table calibration parameters.

The '7747 ECM constantly auto-zeros the TPS. It saves and uses as the base the lowest seen TPS value.

The BPC of 148 is OK. Note that the injectors will go static at a higher RPM then if it where an 8-cylinder engine. There is more time available to fire the injectors on the 6 versus an 8 cylinder engine.

Those dual VE tables are a pain.

It is actual volumetric efficiency, but not to the atmosphere. It is to the intake manifold pressure, as the MAP sensor reading is used in the PW calculation.

RBob.

kevm14

RBob,

Can you shoot me the EBL XDF and WUD? I was going to start poking around in Tunerpro.

RBob

iTrader: (1)

For the latest WUD and doc's, the Update page on our web site hosts them. Just grab the one for the EBL Flash product.

The XDF won't do much good without a BIN and the Calibration Help document. I will state that it is rather complete with over 300 parameter & table entries. The entries are also grouped together along with using a key at the beginning of each parameter.

Such as the spark advance entries starting with "SA - ", the IAC entries start with "IAC - ", and so on.

RBob.

kevm14

I was hoping I could look at a few bins just to see all the different tables and stuff for the elaborated XDF.

kevm14

Why doesn't Tunerpro subtract the main spark bias from the main spark table like Tunercat did? Are people just zeroing out the main spark bias and running the main table natively?

kevm14

All I see is min and max async PW, but no threshold to go to async. Using Tunerpro now...

EDIT: Using Tunercat, I see two other constants that look like what I may want:
Sync mode enable
Sync mode disable

Enable is set to 0.5msec
Disable is set to 0.31msec

So that tells me that ASDU isn't an sync-only calibration, right? Or is it sync-only because async is reserved for very short PW's?

kevm14

So I just placed an order for EBL and the WB kit.

I would like to get an IAT for this setup. Given that this is a non-heated intake manifold, do you guys think a MAT would be better? There are two tapped holes in the manifold, near the #6 cylinder. One we think is 1/4" NPT and the other 3/8" NPT. There is no real plenum so we wouldn't want to thread the MAT in too far, to avoid interrupting the air flow. Any suggestions? I think it would be more useful than an air intake IAT since the manifold is unheated.

ACDELCO Part # 213190 {#25036751}
SENSOR,INT AIR TEMP 2 TERM-3/8-18 THD

Sound right? That's for a Buick 3.8 turbo

kevm14

I made the next bin with Tunerpro, so I can get my feet wet before jumping in the deep end with EBL. The good news is, I think I finally figured out how to get the idle squared away with the 7747. My fault for assuming it would work exactly like my 6965 ($62). The trick was in fact to decrease the IAT steps vs CTS, as has been documented for years now. Sorry.

There is some potential yet to be tapped in the 7747 but we're getting there now. I look forward to knowing PW/DC, PE AFR and correlating the WB logs to AE and getting this thing running mint.

I got Tunerpro up and running with the EBL XDF and looked at some bins. Man this thing has got controls! I'm salivating over here.

Any feedback on my async question? It doesn't seem like you really can have a truly sync-only calibration. Well, first, AE is async, but if the injector isn't stable below like 0.6msec, then it seems to me the only real solution is to run a vAFPR and get the BPC up at light load, rather than anything you can do in software. Am I wrong? Then again, I assume we'll be idling at 1.0 or higher (if we keep FP at 14 psi) so it's not so much idle but decel/light overrun that could be the issue, uncovering the famous sync -> async surge.

Secondly, any comments on my MAT selection? Words of warning? Good idea due to the non-heated manifold? Should we run the IAT in intake tract instead?

Rbob, would you consider moving this to DIY? May be better suited there...

EagleMark

SYnc/Async is a mystery that maybe RBob knows?

What I can tell you is if you have a 1227747 $42 bin and in data the ASYNC flag is always on it sucks to tune, impossible to tune by BLM data period and idle is ridicules.

Now ASDU and other bins do not have Async flag on except for decel or DFCO, it does not come on for AE.

That said with a O scope on injectors it is Sync Idle and goes Async off idle and still no Async flag.

kevm14

Yeah I've done some reading on async bins, and maybe some threads where you chimed in over on Gearhead EFI. It does seem terrible, except perhaps on some mystery 60° V6s...

I will also say my Caprice idles rougher, with a higher MAP when it goes async. I remember I spent some time back in the 2005-2006 time frame trying different things with the sync to async thresholds and ended up reverting back to stock on it. If you're at the limit of the injector, you don't have many choices. Not that I knew what my PW was....anyway.

I would assume that AE is async so you don't wait for a DRP and just get the fuel in right now, at least for TPS AE.

RBob

iTrader: (1)

I always prefer the bird cage style IAT sensors. Isn't the area under the carb heated via the exhaust manifold?

I too haven't found much good for async fueling. Even async AE has issues. The EBL always does MAP AE via sync mode. While the TBI default for TPS AE is also sync. With an option flag for async AE (required for MPFI engines).

Moving to DIY_PROM...

RBob.

kevm14

I remember reading the birdcage style are fast responding. I think that's the type that came stock in my Caprice. http://www.rockauto.com/catalog/more...575&cc=1037427

Yeah the exhaust is right under the intake, but it is now wrapped because it seemed way too hot before. He had some icing issues after installing the Caddy cold air intake. Since disconnecting it from the grill feed (and just drawing from the airbox/engine bay) it seems alright.

I didn't realize EBL did all AE as sync by default for TBI. What does the 7747 do?

Ronny

iTrader: (1)

I swear I ran synch only with 7747/$42. Is there not a flag to uncheck?

Are you seeing PW < .6 at idle? Seems awfully low. Yes a VAFPR would help in that regard as well as make vehicle just run better. Something tells me 7747/$42 does not support VAFPR. As BPW would then be VAC referenced in a table <VAC to >VAC. Not sure how it would run if you just added it. Wont hurt(much) to give it a try!

I would think IAT is a better idea than MAT. My IAT is in a tube leading to a carb bonnet on my TB. Clearly shows air temps ranging from 70dF to 120dF with engine heat sunk.

kevm14

Sorry for the confusion. I read somewhere else that the lower limit for these P&H injectors is in the range of 0.6msec, though it can obviously vary by voltage and fuel pressure. I don't know what the PW is on this truck, and the async issue I was referring to experimenting with was my Caprice many years ago. Sometimes I jump around...

I don't think we'll need a vAFPR on this truck but that depends on how much fuel it needs at the top end.

Roger that on the IAT. Is the one I linked a good one? It was the AC Delco specified for my 93 Caprice. I'd assume it's a common part to other TBI applications. We were going to add one to this truck since I think EBL makes the most of the IAT input (pending proper tuning).

Ronny

iTrader: (1)

VAFPR allows you to reduce fuel on bottom end(ilde, low RPM/MAP). Top end fuel is determeined by inj size, fuel press, fuel pump.

kevm14

Agreed. I think we're saying the same thing. Depending on top end fueling needs (flow combined with RPM), that may require a static pressure and/or large enough injectors that idle becomes compromised, thus necessitating a vAFPR. I was saying I don't expect to need one on this truck, but I'll know for sure when we get EBL and the WB hooked up.

RBob

iTrader: (1)

'7747 does all AE as async injection. It works OK on bone stock 160 HP engines. But not so much once the performance gets increased. Since an async injector pulse can occur at the same time a normal sync injector pulse is taking place, can end up with no AE.

It can also cause a 'chunky' engine response as the AE is sputtered in.

RBob.

kevm14

Just a short update (lies). RBob is converting the $99 mask ECM as I type this, but I think we'll keep the 7747 around and tinker with it from time to time, if only to compare a dialed in 7747 cal to a dialed in EBL cal. And learn something, too.

I was so focused on the idle issues that I forgot to update the rest of the changes...

Cranking:
Originally I had leaned out the warm-hot crank AFR, which fixed the rich start issue. But I became suspicious of having to make that change, and took another look at the VE table. I remembered reading that the ECM uses the 400rpm row to crank (or maybe a blend of 0-400rpm depending on starter speed). I hadn't changed the 400rpm row at all! I had to lean out the 800rpm row so I just feathered the changes into the 400rpm row, keeping the trends logical, pulling out a lot of fuel especially at higher load (like when cranking). Then I put the cranking AFR all back to stock. The result, I am told, is good starts with no throttle needed, cold or hot. Win.

Changed max SA to 54d for 6-cyl large dist cap. It probably needs more than 42d at low map high rpm, so the ceiling has been removed.

For no good reason I changed the pseudo-baro test RPM to 3300rpm (lower) and raised the TPS threshold to make sure it gets a good read.

Discovered the knock retard min VSS was 2mph. No VSS here yet. Whoops. Set it to 0mph.

Raised max BLM mode rpm to 5000 so we can learn in the extended RPM range. Whoops again, as I had previously overlooked that.

I did make that stoich AFR change to 14.1 at Eaglemark's suggestion, and pulled ~4.25% out of the VE accordingly.

Recommended for folks reading who haven't done this: zero your 800-2800rpm VE adder. Make sure the 400rpm and 3200rpm are filled in. No reason not to do this, that I can see, and it makes things easier when correcting VE. Incidentally, my 93 Caprice came stock like this.

Fixed the funky way-too-much-VE at 100kpa in the 1600-2800rpm range, smoothing it from the 90kpa column. Just looked bad.

As previously mentioned, lowering the IAC steps vs CTS table fixed the high idle issue after a start. I lowered it even more than Eaglemark suggested, and I am told that works properly now. He adjusted the hot idle IAC steps to around 4-7 which seems perfect. Sweet.

Got rid of the SA extender and did all my SA in the main table (still have the PE adder, for now).

I have not driven the truck as I sent my father-in-law home with this chip but we're doing better overall. Still needs more work with AE, and I probably will keep playing around with SA.