1989 305 TPI Auto 170K miles. Bosch 3 injectors with correct offsets from Tuned Performance. Only mods are 52mm Throttle body and deleted smog.

When the car is hot (25+ mins of driving) and it is hot outside I am getting intermittent severe stumbling. RPM will drop to 300 for a few seconds and come back up. It will do this until i have allowed the car to completely cool down overnight. I have attached a screenshot of the data log when this is happening.

It will stumble at any vehicle speed. I replaced the oxygen sensor(light green line) based on the data below but there has been no change in drivability. IAC behavior(dark green line) looks questionable to me but I'm no expert.

orange line is BLM which looks pegged at 108 most of the time which is not good.

based on the heat issue I think I will test fuel pressure when this is happening next.

What do you guys think of the below data. I can upload the actual data log if people want the full thing.

the part where it looks like the TPS is going crazy is me trying to give it gas to keep it from dying but it didn't help.

MAF=purple MPH=Blue O2=light green TPS = Red RPM = gray IAC = Dark green BLM = Orange

 

How old is the icm ?
new issue with tune or just developed recently?

 

ICM is about a year old. it came with a new distributor I put on last year. This problem started happening last year but Ive had the tune in it for 2-3 years now. I have an extra ICM from a different firebird I could swap it out with.

 

It could be ignition heat related just a guess. If you do swap icm use a heat sink compound thermal paste like arctic silver.

 

I have eliminated the stumbling and bogging by drilling a hole in the gas cap. My gas cap would always let out a violent whoosh of escaping air with a sealed gas cap. the pressure buildup from the heat must've been the cause of the problem. So the car is running better but now occasionally I can smell gas fumes with the ttops off. The gas cap hole is a temporary fix. What is the proper permanent fix?

 

https://www.hawksmotorsports.com/82-...-reproduction/

 

Do you have an .XDL file instead of the graph you posted above. Very hard to read.
Thanks

 

Sorry looking back at it its pretty confusing yeah. Here's the xdl in a zip folder. it didn't let me upload it on its own. It starts to act up around the 25+ minute mark.

I was driving today and it was 92 degrees out and after getting home from work I let it sit and 30 min later I went to restart it and it was doing the bogging and stumbling briefly but it worked itself out of it after a minute or two and I was able to drive. I haven't been able to observe the fuel pressure when its stumbling.

 

I have reviewed your log.

1) Do you have a 160Deg thermostat? If no, your thermostat appears defective opening up to soon with great variation. If yes, your fan is set-up too high.

2) 1989 305 TPI Auto 170K miles. Bosch 3 injectors with correct offsets from Tuned Performance. Only mods are 52mm Throttle body and deleted smog.
FYI, the AIRS (Air Injection Reaction System) is still active in the BIN. It needs to be disabled if the AIRS has been removed. Reason is when AIRS pushes air to "Port", the ECM compensate O2 sensor signal for extra air. I can't assume what you mean by "deleted smog". Please explain exactly what you did.
Also, 52mm throttle body on an LB9 might be too big. I can see your IAC is struggling and taps out when in gear at idle. It reaches 0 count trying to maintain 550 rpm idle and it can't.

3) When the car is hot (25+ mins of driving) and it is hot outside I am getting intermittent severe stumbling. RPM will drop to 300 for a few seconds and come back up. It will do this until i have allowed the car tocompletely cool down overnight. I have attached a screenshot of the data log when this is happening.
I can not see this reviewing your log. The lowest the RPM registered is 450 only once (blip on screen)!

4) It will stumble at any vehicle speed. I replaced the oxygen sensor(light green line) based on the data below but there has been no change in drivability. IAC behavior(dark green line) looks questionable to me but I'm no expert.
In your log, your O2 sensor voltage is definitely problematic. Yes your IAC taps out to zero. Throttle body too big or not adjusted properly.

5) orange line is BLM which looks pegged at 108 most of the time which is not good.
The ECM is in and out of CL. There is something wrong. The ECM will not stay in CL. When in CL, it appears your BLM are erratic going from 107 to 158. Do you have a new MAF?

6) the part where it looks like the TPS is going crazy is me trying to give it gas to keep it from dying but it didn't help.
All I see is corrupt data once in a while (normal when datalogging).The TPS is not going crazy, what ever that means.

 

I can see at some point, as you are accelerating from 5mph to 37mph, the BLM goes from 155 to 128 to 158

I suspect these extreme BLM changes in conjunction with being in/out of CL makes the engine stumble.

Something wrong with O2 sensor. Was it relocated? Headers?

 

1.) Its got a 180 thermostat that i put in it.

2.) I removed the air injection system entirely. It now has long tube headers with no cat. smog pump was removed as well.

4.) I was thinking the same thing about the 52mm throttle body being too big so i sourced a stock one that is in good shape. I will install that and reset tps and iac.

5.) I had just put in an original bosch MAF for the first time on that datalog to see if it would run better. I have an aftermarket Delphi unit that I ran on it for a few years prior that works.

6.) Oxygen sensor was relocated to the top of the driver side header collector. It is a new single wire unit in this datalog because I thought it was bad by looking at other datalogs i have run.

 

Its got a 180 thermostat that i put in it.
Well, by the look of it, it starts flowing just shy of 160°. Then, as speed increases, it brings it down to 160°. When you are standing still it goes up to 215°. Your fan comes on at around 215° and shuts off at around 202°. Something is up with that. Fan should be synchronized to take advantage of 180° thermostat. Something like on at 192°, off at 190°. Just an example. It's the way I like it but there are probably zillions of opinions out there. Properly functioning thermostat will start opening at 180° and be fully open around 190°. I suggest you use a infrared thermometer gun to confirm CT sensor accuracy.

Red=CT / Green=speed


2.) I removed the air injection system entirely. It now has long tube headers with no cat. smog pump was removed as well.
When you said: "Only mods are 52mm Throttle body and deleted smog.", you forgot to mention the headers.
Anything else? About EGR and CCP?
You need the AIRS to be disabled in your tune.

4.) I was thinking the same thing about the 52mm throttle body being too big so i sourced a stock one that is in good shape. I will install that and reset tps and iac.
You got that right. Not to be an a**, but you have a whooping 195HP 305 with a 2.73 gear. The 52mm TB won't give you anything more for your hard earn $$$. The mods to the exhaust is nice, but for the insignificant HP gain, it makes the car real loud. Extra 25hp?. Our 3rd gen F-Bodies, even with basic bolt-on mods are becoming a joke compare to any 2.0T car out there. I'd rather keep them stock and be under the radar than be loud and be laughed at on the freeway. Just my unsolicited opinion. OK, now I am starting to sound like @sofakingdom

5.) I had just put in an original bosch MAF for the first time on that datalog to see if it would run better. I have an aftermarket Delphi unit that I ran on it for a few years prior that works.
Be aware that every time you change the MAF, the tune might be off, specially at low RPM. Just the way it is. The Delphi can be problematic https://www.thirdgen.org/forums/tpi/...maf-issue.html
Also, the MAF does not adapt well to modifications like the theory suggest. Specially at low RPM.

6.) Oxygen sensor was relocated to the top of the driver side header collector. It is a new single wire unit in this datalog because I thought it was bad by looking at other datalogs i have run.
The first thing that stood out looking at your log was the O2 sensor voltage and the ECM going in/out of Closed Loop (CL). It seems that when it's idling, the O2 sensor stops responding. It could be a classic case of O2 sensor being too cold. I recommend installing a heated O2 sensor activated by fuel pump relay.

Red=O2 voltage / Green=speed

 

Could you attach your BIN file (tune). I am curious to see what you have.
Thanks

 

Before you start testing your thermostat in a hot water pan on a stove top, please read this:

https://www.thirdgen.org/forums/cool...tested-ok.html

 

I will attach the BIN when i get back from work. EGR and CCP is all stock.

So here's a list of things I need to do based on your very helpful feedback.
1.) Heated O2 sensor
2.) put stock throttle body back on and reset TPS/IAC
3.) 195 thermostat to match fan better and confirm CTS readings with laser thermometer.
4.) disable AIR injection in my tune.

 

I would say more like: fixing the thermostat issue, If you go with 180, you just need to adjust fan in tune. Should be easy since you have to adjust tune anyway for AIRS delete.

Yes start with heated O2. It's inexpensive and a must. That will eliminate the possibility of cold O2 issue.

I'll wait for your tune and have a look at it

 

So I have completed items 1 and 2 on my list of things to fix.

I installed a heated O2 sensor. and put a stock 48mm throttle body back on and reset minimum for IAC and TPS using the method described in my service manual.

Then I went for a drive and did a datalog. it wasn't very hot today and I didn't go for a long drive so My hot stumbling issue didn't happen on this datalog.

The code 42 was from disconnecting the timing advance while setting minimum idle. I had a code 22 pop up earlier this week ( I cleared it when I switched throttle bodies) and it came back on this datalog.

I believe it occurred while full throttle on the 3 to 4 shift or lack thereof. It missed 4th entirely at full throttle and there was a decently loud clunk. this is the second time this has happened while WOT. driving normally it'll go into 4th fine. might need a trans soon.

as seen in the attached datalog its still pegged at 108 when the throttle is not pressed. when I press the throttle it goes right to 128ish however. so maybe its fine for now.

I still haven't changed the fan on off or disabled air injection yet. I still plan on doing those things as I have a burn2 from moates but I haven't used it yet. maybe one of you could walk me through it on a phone call.

I'm going to keep driving the car this weekend and see if I can get it to stumble when its hot.

 

Re post#17

• O2 sensor voltage looks way way better.
• Upon releasing your gas pedal after your hard acceleration, your TPS went too low for unknown reason. That is your code #22. TPS voltage is RED, speed is GREEN.

• Your BLMs are all over the place. It's complicated and I don't have time to get into it. But it has to do with SAM be activated, changing MAF and BLM cells boundaries not being optimized. BIN needs to be optimized to enable a smoother MAF table recalibration. Example is, cell#15 is shared with normal cruise and WOT. Cell #15 becomes lean and BLM shoots up to 141. When in WOT (power enrichment mode i.e PE), cell#15 is activated but locks at 141. At same time, commended AFR goes to 10.78:1. Complex!!! Attach your BIN please.
• IAC looks pretty good
• You experienced knock event in WOT. Graph is a bit hard to read. RED is knock retard (KR). Every time the red line goes up, it's a knock event. When it goes down, it's all good. GREEN is your RPM. BLUE is commanded SA. You reach max of 38* at 4650rpm. LIGHT BLUE is your real SA. You have to add 6*. You go as low as 16.9*!!!!! I told you SA tuning is a pain. Are you using 93 octane?. Looks like it knocked only at 30* SA.

"maybe one of you could walk me through it on a phone call."
There is tons of info on how to use the Moates PROM burning. It's not user friendly, so you have to be patient and you will get it. I can't do a phone call, maybe someone will.

 

Here's some good info for you to understand how this madness works

That's my dashboard.

It tells me you have your foot to the floor. PE is activated and KR is doing some work pulling -5.1* SA. Commanded SA is at 36.9*, which is too much for my likes on a stock LB9. Real SA is 31.8* (36.9-5.1). MAF indicates 144.87g/s at 4550rpm. This makes no sense on a stock LB9. You should be at around 180-190g/s. Thus LV8 is also low at 154. LV8 is a calculation based on MAF and RPM. Having such a low LV8 could affect commanded SA as well. The commanded PE AFR is ecm calculated at 10.78. Injectors are opening 9.93ms (INJ BPW). But that does not account for voltage compensation. They are probably more like 10.5ms which gives us a near 80% duty cycle. O2 sensor voltage is at 870mv. That indicates the mixture is around 12.5:1 (this is just an estimate. Only an AFR gauge can confirm that). BLM is locked at 141 in cell#15. Integrator (INT) is locked at 128 which is normal in PE.

Problem with this picture is that by having a MAF reading this low, the ecm has to compensate with a BLM at 141 (+10%). If I increase MAF to 159.4g/sec and keep INJ BPW constant at 9.93m/s, I get BLM 128. If I decrease AFR to 12.8 with MAF 189.2g/sec and keep INJ PW at 9.93ms, I get BLM 128. Conclusion, MAF voltage scale in BIN is not accurate. Why? Could be the BIN you have or it could be the new MAF.

Sorry for the km/h speed, I had the CND version on.

 

Thanks for the help so far. Your explanation makes sense to me. I will get the chip out of my car and copy the BIN for you to look at soon.

I am running 87 pump gas in it. should I be running 93? would that eliminate the knocking or just make it less.

The MAF is an old original bosch unit. I also have a newer style Delphi MAF i could swap in. I currently have the cut open air box mod and the SLP baffled air inlet tubing. I don't think those would decrease the MAF readings that badly right?

 

Re post #20

87 octane!!!! Yes you must run 93 like your original GM manual states

Don't know why you are getting such low MAF readings at WOT. Maybe the MAF is not accurate anymore. We don't have a baseline to compare to. Vacuum leak? However, readings seem normal at idle.

One of the low milage OEM LB9s with stock BIN I have tested recently, gets at WOT, on 91 octane:

• MAF: 180.2g/s
• RPM: 4475
• PE AFR: 10.78
• LV8: 193
• O2 voltage: 955 (way too rich, confirmed by AFR gauge)
• CT: 203
• MAT: 47.7
• SA: 31.3*
• KR: -2.1*
• BLM: 128 in cell #15

Of course I retuned the PE AFR and actually increased performance a bit by removing fuel. Also, the 91 gas here in Atlantic Canada is sh**. Makes every performance car experience KR. GM had those LB9s on the rich side at WOT.

 

Let me add to my comment from post #19:

By having your MAF readings out of whack it actually corrected GM over rich oem programming at WOT. Quite ironic!!!

However, I believe it increases your commanded SA at WOT because you get a low LV8. Here's an example:

Instead of LV8 193 you get 154. SA increases to the low 30s* from 26-27*. You add 6* of PE SA and you re in the high 30s* instead of low 30s*. At 176* CT, there is no CT SA correction.

Table from APYS ('89 LB9, 5speed, 3.08)

 

I took my PROM out and made a copy of the BIN that is on the chip. I have attached it to this reply.

What is the correct BIN definition for an APYR BIN? When I open it in tunerpro all the values are way wrong so I'm guessing I have the wrong definition. The one I have is 6E.xdf from tunerpros website.

 

Seems like your BIN is corrupt.
'89 TPI is $6E.
You most likely did not download it correctly.

 

Ok I think i had the wrong chip addressing. I changed it for 16K bin size and it seems to read correctly now.

 

Re post #25
Reviewed your BIN APYR.
It's not a BIN I had in my archives. I could only compare it to APYM ('89 F-car 5.0TPI auto with 2.73 or 2.77). What is your rear end gear ratio?
The only differences are minor changes to MAF tables and quite the change to INJ voltage correction table. Was the BIN extracted from the original PROM or is there a piggy back chip on your PROM?

I have attached 2 BINs:
One for a properly functioning 180T, and one for a properly functioning 195T.

• VATS disabled
• ALDL Spark adder zeroed-out
• Fan adjusted accordingly
• AIRS disabled
• BLM RPM Boundary #1 adjusted to 850rpm for warm idle improve accuracy

 

rear end is a 2.77 Borg warner. I have the moates G1 piggyback board. the original APYR PROM is there but it is not used. the one being used by the ECM is the APYR B3 i got a few years back from tunedperformance that was a stock APYR bin with only the injector voltage offsets adjusted for the bosch III injectors. The bin i sent you was the one from tunedperformance. not the original bin.

 

Great!
Could you extract the original APYR from your PROM?. I will add it to my archives
Thanks

 

I will get you the stock tune. In those custom bins you posted, do they have the injector voltage offsets for the bosch III already or do I need to add them?

 

do they have the injector voltage offsets for the bosch III already: YES
or do I need to add them? NO

They are "APYR B3 V2" you posted at #25, with the following adjustments:

 

here is the stock APYR bin you wanted. 1989 formula firebird 305 TPI auto trans 2.73 gears.