Hi folks,
I've got a fresh (<50miles) rebuilt 1988 350 TPI, and it runs well, timed good, idles good, starts easily. It has new plugs (gapped to 0.035"), wires, cap, rotor, and pickup coil. Ignition coil seems fine, so haven't replaced it. Tested ICM at Napa, tests fine. Tach and engine are smooth. Fuel pressure good at rail. No codes are set.

Here's the issue: I can't chirp the tires or even get close to breaking loose, and it loses top end power, to the point where I can't accelerate up a hill easily, especially freeway speed (has a T5, 5th gear on freeway is a laggy up a hill). What else could I check? Everything runs fine aside from a loss in go-power, and no throw-back-in-seat feeling like my older '85 305 TPI. It's like it's not getting enough air/held-back, but I have a new air filter (K&N, clean, well oiled), and everything is open that I can see and not blocked. New cat that's got a few hundred miles on it, and brand new muffler as well.

Checked TPS with moates/TunerPro RT and TPS goes from .47 to 4.37 at WOT so that seems to check out. Could it be a bad MAF, and what readings would I see on TunerPro (airflow area) if so?

 

Exhaust restriction? Old muffler/bad cat?

 

Like I said above, the cat is new, so is muffler. Just replaced ignition coil this morning; no more occasional tach jump. But still a dog/acts like partial throttle.

 

Where is your base timing set with the newer/fresh engine...?

- Rob

 

6-7 degrees (with wire pulled).

 

Parts w/check list above seems good, but what exactly did you do though... swapped an LB9 for an L98. Same ECM, and same size injectors? If it's holding back I would lean more towards a fueling issue. The MAF didn't seem to give you any trouble when you were running the LB9... correct?

- Rob

Edit: Unless this is another car entirely, and not a swap?

 

It had a L69 HO carb engine with T-5 in this 1986. Was tired, needed a rebuild, so bought a wrecked '1988 GTA (rear end damage), pulled all wiring, TPI setup (honestly all engine bay stuff from the 1988 and interior/dash/fuse/ecm), put it in the 86. So it's a 1988 350 TPI. Had the 350 professionally rebuilt while at it. I have GM's service/wiring manuals, and everything is soldered and heat shrinked (if splicing needed, just to lights/body) otherwise all is OEM uncut 1988 harness from wrecked GTA. I never fired it up before I pulled from the donor vehicle, so don't know about MAF integrity; which is why I was asking if I could monitor readings in TunerPro to see if it wasn't reading out properly under hard acceleration. Perhaps it's injectors? But would my symptoms above be bad injectors? Like I say runs well until I mash into it, and even then it runs smooth, just doesn't have power. I'll give SouthBend a call tomorrow, they are cheap enough.

 

I was just reading through your other thread in the tuning section. Can you post a datalog in either thread, because there is a way to check if something is off. Remember we are tuning fuel to a given amount of air. The air is a constant. Either the MAF is metering poorly, fuel pressure is dropping, or the injectors are garbage. A datalog will give plenty of clues...

- Rob

 

What’s afr in pe ? I see your tuning it in the other thread

 

Havent done a log yet but I’ll do so and post it. Anything special to record or just take the default values that came with the AXKY?

Whats PE? I was only “tuning” to adjust fan turn on and off, and remove egr.

 

Pe is power enrichment, you need to datalog to try to determine what’s going on.
have you looked at your blm in cl ?
you might also want to do a custom tune with a manual bin as a starter. Like 89 vette manual apyp but recurve timing.

 

Hi,

Check your throttle body sensor. Make sure it's putting out the correct voltage.

 

covered in post 1

 

yes your right, read it too quick at first.

Thanks

 

So, about to run over and log this climbing the hill. Do these spec files (adx, xdf) look ok for logging? I just want to make sure I capture all the data you're looking for. I've logged with HPTuners, but not TunerPro RT so I'm not sure if there's anything else I need to set.

 

Im not sure if thats the $32B adx. where did you get it ?
I have attached a copy that I have used that should work.
Make sure you put the ecm in the 10k mode to connect and one connected disable the 10k jumper.

 

sorry having issues with attaching a zip file

https://www.filehosting.org/file/det...227165.adx.zip

 

Ah shoot! Missed your reply. Well, here's the log, in 10k mode the entire time. Why do I need to switch it to the outside once it connects? I don't mind doing it, I just want to understand why that way I can remember it easier.

Started driving/recording at 0:
0:06 - SES light came on, headed south on freeway, 65mph in 5th, slight downhill
0:10 - Turned around, started from stop, up steep onramp north and long 2-3mile hillclimb
0:11 - 4th gear, 60mph
0:12 - 5th gear, slowing down now to 50mph, back to 4th
0:13 - 5th gear again, stayed in 5th until grade leveled out
0:14 - Slight acceleration on slight uphill grade
0:15 - SES light on again, then off, on again at 0:17, got off, town driving

Throttle doesn't seem to do much in response past 2.5-2.6 on the TPS.

Hopefully you can use this to get some info as I can't log again until tomorrow afternoon. This is the GTA's chip, that I dumped, changed fans to come on earlier, disabled EGR, and toggled from automatic (that GTA had) to manual (that L69 had). Shucks, wish I had caught that message about the a-b 10k jumper. And I am using a $32B.xdf (and 1227165_160 adx as well, which is $32B and I believe I got it from the gm efi forum, or my other longer thread in the DIY prom section).

 

First thing that came to mind was the knock sensor, but you'd hear pinging during uphill acceleration, which you didn't mention. If you did mention it, then sorry for missing it, but I lost track when I read this...

Say what?! Not to sidetrack your topic, but was this 1986 L69 car a Trans Am or an IROC? Not many of either ever existed. Might've been worth saving. I guess there's one less now.

 

Yep, I know. A trans am, I think only 20-30 were made with the combo. As I did the swap years ago at the time I can’t remember what my reasoning was behind it, but no starting due to vapor lock in the heat rings a bell and it happened a lot. Now looking back might have been easier to stick with the l69 carb and hunted for missing parts and going that route. I think I still have some of the engine parts saved in boxes, so it’s not a complete loss, and I didn’t really hack anything up; but yes I’ve thought the same thing; what was I thinking?

 

You might want to switch to $6e much better adx. Unfortunately the adx I have doesn't show much as far as timing goes. Im not sure the correct address values to put in to add new items. $6e adx already has the spark advance and retard. your running real lean blm looks almost locked at 150 and knock counts are high. believe running in 10k mode locks timing and this could be where the pinging is coming from.

 

Just curious, what cam and injectors are you using?

 

Stock, original injectors. Cam - can't remember; not a "hot" cam but I believe it was an 80s corvette profile. How do I switch to a $6e? Just load it then log with a $6e adx? You're not talking switch/reburn the chip, correct?

 

Yes, I’m talking about using a $6e bin
ill do some more looking at the log today but you might pull a plug or two and do a read.
looks lean though.

 

I pulled and gapped all plugs this weekend and they looked normal to me, and I’ve pulled a few plugs in my lifetime. No oil or carbon buildups.

 

Normal as in tan in color?

 

Brian, did you look at the bin he was using? Never bothered to look at AKXY myself in all these years, only ARAP, but does this even seem normal to you?

- Rob

 

That doesn't make sense, are you looking at it in a $32B xdf ?

 

Yeah that was it, was too quick when selecting the XDF in Tuner Pro. Was saying to myself...; I knew people avoided AKXY like the plague, and when I happened to see that, I was like, hmm I now see why lol. But yeah, just uploaded the correct XDF and it looks good...

- Rob

 

Lol, guess it’s one of those differences when looking at $32 and $32B.

 

Forgive me guys as this is the first time I am even looking at this XDF. Now, I would have to assume that the values in; SA - In WOT vs RPM are being added to SA vs RPM vs Load at WOT, correct?

Bob, your EBL has really spoiled me over the years...

- Rob

 

When cross referencing both threads, I thought you had already switched to $6E? You mentioned dumping the existing bin and going $6E way back in 2013 lol. If you run $6E and experience the same exact scenario, this will at least help narrow it down in terms of a tuning issue, or fueling issue (mechanically)...

- Rob

 

yes, normal as in clean/tan.

So I’ll await what you too gurus want me to do. Yes I have the oddball 88. Sheesh.

 

This should have been done a long time ago Kevin...

https://www.thirdgen.org/forums/diy-...ml#post5665738

The 1989 code ($6E) is better, but need to use a '89 BIN and the $6E definition file together....

 

Yep I was thinking of that with my other thread, but I was also thinking surely that isn’t the only problem at the time (obviously not since I replaced nearly all the ignition stuff now). But now that I’ve weeded everything else out I’ll do the burn. It couldn’t have been this bad off the showroom floor, but if the ‘89 bin helps that much for diagnosis I’m on it. Give me a few hours and I’ll post the results and log.

 

I think you’re asking about the pe adder or subtraction In wot

 

Values are a little bit different from what I was looking at, unless you nabbed a screen shot of a different bin altogether, screenshot below. If PE based then makes more sense, it just doesn't specify Power Enrichment in the XDF like I have gotten used to over the years...

- Rob



Not to derail the thread, but this is what I am referring to in regards to PE...;

- Rob

 

So if I want to disable EGR in the $6E, it should already be disabled as the bin I downloaded has "Disable EGR if MAT < X" at 0.50 Deg F, so no changes need to be done, correct? What about the SES that might come up with no EGR equipment? The AXKY had a flag I could uncheck for the code. I'll also uncheck VATS Enable as I don't have it, and check the box for Manual Transmission. Anything else before burning?

I used the $6E ARAP bin from here: http://tunerpro.net/downloadBinDefs.htm#GM

 

super_kev send me a email at brianlvs@yahoo.com , having issues uploading a bin you might like to try.
will have to see how it runs and if fueling and timing need adjustment.

 

Should upload fine to forum if you rename the zip without any special characters... ? Email sent.

 

He knows that... he just doesn't want anyone else to examine it lol....

- Rob

 

I have tried to attach as a zip no go. Just stays on the file finder /upload page.

feel free to upload here. No rob I made it a virus to wipe out your ebl calibrations lmao.

 

LOL....

- Rob

 

Posted in my mega thread by accident last night, couldn't figure out why I couldn't see my post this morning, haha. Still acts like one is light on the throttle. This tune is much better, much more responsive. I do like the $6E definitions, dash, all the data one can see compared to the AXKY. Here's the log - different run than last time (different area) but still had a few places I shifted into 5th and it lagged from 65 to 50mph.

I shifted from a lagging 5th into 4th gear again to gain speed around 1:12 up a slight uphill (not the grade from earlier AXKY log).
Got off freeway and started up a hill the other way around 2:52, and shifted from 5th back into 4th gear around 3:56 to not get run over by a semi.

 

Do you have headers ?
No closed loop operation and code 13 for o2 sensor.
the o2 really didn't move off.450
looks like either the 02 is dead or there is a break in the wire going to d7 of the ecm.

 

Nope std GTA/350 manifolds. The O2 value was bouncing all over; I saw it hit 300s and 500s a few times but yes it mainly moved centered around 450. Wouldn't that mean it's connected and no wire break? Edited above to add a few timestamp events (lagging areas) in the log.

 

I watched 3/4 of the log. After I saw no closed loop operation I saw no o2 movement.
i guess the best way to try to diagnose it would be get it up to operating temp which it was at 196f.
back prove the ecm wire at d7 it’s a purple wire and observe voltage. Was the o2 swinging at the end of the log ?
ill watch it later today have to run some errands. Could also be at the connector at the o2 .

 

Gotcha. Saw it bounce briefly into the 3s and hit a 5 starting around 3:14 for 20s or so, but I've never watched an O2 sensor - should the values be pretty smooth vs. so jumpy in the log? I take it the ECM is reporting a multiplication of voltage which is why it seems it moving so much, otherwise it'd be staying around 4.5V and moving between 4.2-4.6V or so, right? I'll test the wire this afternoon.

 

The reading is in mv. Once to operating temp 5-600 f the o2 will swing .450 is the middle pint of the swing.
staing above or below the swing point will indicate rich or lean for a extended time. Above .450 mv is rich.
the blm will reflect this as well. Spot build up on a 02 from running rich will kill it as well.

 

Ah, so what you're saying is that .450 is fine, which is where it's mainly at (aside from small blips either way at times that I see in the log as the ECM corrects for rich or lean). So that means no problem with O2 then... especially if engine runs fine, aside from this loss of power like the throttle isn't being put down more, perhaps due to fuel pressure drop under load? There's no studder or unevenness like I would expect if injectors were failing, and I wouldn't expect all 8 to suddenly fail and operate smoothly at a 50-60% capacity (just tossing out a random number there) without a few firing fully and causing a rugged sound due to more explosive and powerful combustion in a few cylinders that are getting full fuel.