92 Formula

iTrader: (2)

Late February or early March my trans went out on me. I replaced it with a Pro-Built 700R4 and a Vigilante 2400 Stall and got the car back yesterday.

When I was driving home, after approximately five minutes...perhaps ten, I lost power (engine power) where the SES light went on and the speedometer dropped to 0 for the same time period. It then drove fine for about five minutes again. The above would repeat itself...always around 60 miles per hour in D or OD...that did not matter. After some time it would happen at any speed and in any gear (the shop was 30-35 miles away from my home). ANYTIME I was hard on the throttle it would happen and then, too, it would backfire.

I have only one code: EGR 32. I have never re-installed the EGR from the day we swapped in the L98 to replace the LO3. I have had some kind of electrical power drain, as well, since the day of the swap but have never been able to track it down. I do not know if these problems would be relative to the main problem, but offer them in full disclosure.

Once again, my car is now undriveable. PLEASE guys/gals, you have far more experience and I am really praying you all can lead me in the right direction.

Thank you in advance for your time and any help you may provide.

Here is the car in current form:

1992 Pontiac Firebird Formula (original 305 TBI) Now: 1986 Corvette 350 TPI, SLP 1 3/4" Headers, Dual Catco Cats, Pro-Built 700R4 Street/Strip, Vigilante 2400 Stall TC, Flowmaster American Thunder 3" Exhaust, !EGR, 3.42 Posi and JEGS Ultimate Support Cover for 7.5 rear.

thirdgen88

Do you have anything to hook up to the ALDL (laptop??)?? After I got finished with my E-Tec conversion on my GTA, I was having similar problems (speedo drops, engine stumbles, SES light on, then okay for a few seconds, then repeat) and was losing ALDL data stream at the same time. It was going in and out of limp-home mode.. Turned out to be a bad ECM... Seeing as how yours is less frequent, it might be something else (ignition??)... Thats why I'd hook up a scantool...

You should have an EGR code either way, unless you turned it off in the PROM...

92 Formula

iTrader: (2)

I do have a lackluster scantool: Sunpro ScanTool. It is from this that I got the code 32. When I get home today I will run it again while running and make sure I'm going into closed loop. What should I be looking for from the scan that would be contributing to this?

Thank you for your response.

RB83L69

Sounds to me very much like a fuel delivery issue.

Watch your fuel pressure while it's doing it.

You might want to just swap out your fuel filter if you haven't done it lately.

In any case, it has nothing to do with the transmission.

92 Formula

iTrader: (2)

From my scan tool taken in Park:

BLM 131
BLM Cell 4
Eng RPM 725-775
Exhaust 02 Lean unless I use throttle
Fuel Pump (V) 13.7-13.8
IAC Pos. 17
Knock Ret. 0
Knock Sensor 0
Loop Status Open (Even at 214 degree coolant)
MAP V 1.47
MAT F 95
O2S (MV) Quick Ranging from High 200's - 600's and back again
O2S Crosscnts 0-232-500
Spark Adv 17-25 at idle
TPS Sensor .58

It does go into closed loop when driven.

Anything above look suspicious?

92 Formula

iTrader: (2)

Thank you for your reply. Sadly I do not have a FPG. I do have a scantool, though.

This is probably a stupid question, but with the speedometer dropping to zero while this happens (perhaps the tach and gauges as well...it happens so I quick I have not yet noticed)...does that sound electrical?

Hellraiser

I would say if your o2 readings are fluctuating that much (400+-) even at full operating temperature the sensor may be a bit flaky, u might consider replacing it. Doesnt sound like the whole cause of your problem, but suspicious just the same.

Anyways, depending on where your "electrical draw" it may be exactly whats causing you so much grief with this thing. Try removing one batttery terminal, and with the ignition and all accessories/lights off connect a voltmeter in series between the battery and the terminal wire. Measure for amps (not ohms!!!) and let us know what you find. it should read next to nothing, any substantial amp reading would indicate a large draw/short to ground. if a large draw is the case, start unhooking things one by one (alt, amps if you got em, power hatch motor, starter, etc). check your battery wires/ground as well to make sure nothing is shorted/loose.

A quick check of the relays for maf and fuel pump wouldnt hurt either, alot of these cars will still supply power to the pump via the oil pressure/safety circuit even after the relay has failed. good luck

thirdgen88

That fluctuation is normal operation.. It fluctuates back and forth between lean/rich (trying to get as close to 450mv which is stoich). If you are stuck on one side or another for a prolonged period of time, that would be something to worry about.. If you are getting a good frequency of O2 cross-counts, you're okay...

92 Formula

iTrader: (2)

THANK YOU EVERYONE for replying. I have as of yet been unable to check my fuel pressure. I am also going to re-check my ground strap...since this problem began after a transmission replacement. Maybe something happened then. It is raining like heck here and is supposed to continue for several days but I will look the first chance it lets up.

thirdgen88,

In case you missed my earlier question to you: This is probably a stupid question, but with the speedometer dropping to zero while this happens (perhaps the tach and gauges as well...it happens so I quick I have not yet noticed)...does that sound <more> electrical <as the problem>?

Thanks guys, I really appreciate your help.

thirdgen88

Ahhh... Yes, it definately sounds electrical... Check those ground straps (there is a big cluster that goes to the passenger side cylinder head, and some on the other cylinder head as well)..

Have you been able to repeat the problem with the scantool hooked up?? do you lose the data stream when the problem happens??

92 Formula

iTrader: (2)

I have not been able to repeat with the scan tool yet. I will try Monday. No codes, other than the aforementioned EGR, has been recorded...but EACH time this episode happens the speedometer goes to zero and the SES lights for no more than 1/2 second to one second.

92 Formula

iTrader: (2)

Sorry I haven't been able to update this since my last reply, I have been fairly busy due to personal reasons and will likely remain so until after the first week in May...however...

Between the last post two new symptoms have become evident:

1) Out of approximately 15 times starting the car, two of those were very hard starts. In detail: it would crank continuously with out firing and then when it would start it would die almost immediately. After a few times (on these two tries) it would start and rev to about 2,000 - 2,100 RPM and then act fine.

2) After the car experiences the problems listed in my very first post, the car will sometimes stall at a stop, or when shifting from Drive to Reverse (I back it into the garage).

Once the symptoms of my first post act up they do it over and over again until you reach your destination. It has only backfired once; I should clarify that from my first post. Before the symptoms show up the car runs very strong for the very limited mods.

Does everyone still lean toward fuel (fuel pump/fuel pressure/fuel filter) or how about spark?

The fuel pump is less than two years old with no more than 500 miles on it.

TRAXION

James,

The fact that this happened on the way home from the tranny shop is, for me, the point of focus. There's a good chance that they didn't hook something back up OR they accidentally caused a problem. It is really acting like an electrical issue and I think you are on the right track with the ground straps. It goes without saying to also check to make sure that the battery is hooked up nice and good. I had a similar situation happen a long time ago when did my first cam swap. I was driving down the highway and the thing just cut out. It was sporadic. Sometimes the car would stutter (the ground strap moving from a good connection to a bad connection). After tracking it down I found the loose ground strap and fixed it. At this point I also installed an additional ground strap from the battery to the body (an old trick that most don't know about).

Now, with that said, if all of the grounds prove to be good then I would focus on spark first and fuel second. If you have an aftermarket ignition (MSD, Accel300, etc) then take it out of the system (I've had an MSD go bad and be faulty like that). Also - A bad or faulty Ignition Control Module could cause a similar problem. A bad pickup coil in the distributor could also cause a similar problem. I again had a sporadic problem on the IROC recently that finally proved to be no spark. It wasn't the MSD and it wasn't the coil. I ohm'd out the pickup coil and had the ICM checked locally. Everything checked out but somehow I knew it was someting distributor related. I didn't want to mess around with it so I purchased an entire new distributor from Scoggin Dickey (comes with new ICM, pickup coil, etc) and the problem was fixed. So far I have yet to have a fuel related issue that has these symptoms (not saying that it couldn't happen, I'm sure it does). The next time the car doesn't want to start grab a plug wire and jump it to ground to see if you are getting any spark. That's how I verified that mine was a no spark issue. PLEASE keep in mind that this is ONLY after you have verified that all the ground straps are AOK. A bad ground strap will cause a no spark so you don't want to misdiagnose it.

The O2 sensor will always widely fluctuate under normal throttle. That is normal.

Tim

92 Formula

iTrader: (2)

Hi Tim,

Thanks for the reply.

I've been checking the ground straps and connections one by one using the schematics from the 92 Firebird Service Manual. I feel confident about the battery being okay, I do have a ground strap from my battery to a known good ground on the body. I agree with you 100% that this developed due to the trans swap, as before the car was perfect. I have had no success in catching a code yet, other than the aforementioned EGR. I will check everything you have suggested.

Although I do not have an aftermarket ignition, I began to suspect spark as a real possibility with the no start/hard start. I replaced the cap and rotor in September 2000 and have less than 1,200 miles on it. I will check that tomorrow. Thanks for being specific, I might well have not looked into the ICM. I have already checked the wires and for a cracked cap (cap was the first thing I checked since it's not uncommon to crack them if you're lazy during the trans swap).

Point taken. Thanks for your time and input Tim.

I will report back as time allows me to look into all of the above.

James

Trickster

Hello James,

I know this is probably a shot in the dark here. But, have you tried adjusting the throttle valve cable? Just a thought!!!