i have a 91 camaro rs. The compression is 160 in all cylinders, and the injectors are good, yet my car misses once warmed up. It will even stall out the motor sometimes. When i reset the computer the problem goes away, but seems to reoccur after a few times being started.

 

When was the last time the car was tuned up? Have you played w/ that TPS or IAC sensors at all or moved them? A good tune up always helps & that's including new O2 sensor, PCV valve, New EGR valve, plugs, wires, etc etc. This should destroy your problem. Do you have any codes popping up on your computer or a better question would be has your SES light come on yet?

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- Mike Harvey -
1986 Firebird S/E

 

I agree, it's probably a tuneup issue. Either that or you haven't added dry-gas to your tank in a while... get one that's safe for fuel injected engines.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

I put in a new TPS, IAC motor, O2 sensor, and plugs, cap and rotor has been on for about 2 years

 

I assume you adjusted the TPS per spec with a multimeter? And two years seems long to me for plugs/wires/cap/rotor... what about the air filter/fuel filter/pcv/timing/TV cable?

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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

HAve you found it yet. I think you are really missing 2

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92 Mustang GT
Faster than Your car!!!!

 

I just put on a new cap and rotor, and it still does it. I tested the TPS with an analog multimeter, its good, the pcv is good the fuel and air filters are also good. If i reset the computer it runs fine. Then when i restart the car it starts missing again. I even regapped the plugs just to be sure. I just want to fix this piece of junk and sell it.

 

I didn't know an analog multimeter was accurate that low! Cool.

If you just want to sell the car, then take it to a mechanic and have him fix it.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

hey again, long time no talk to people..

anyhow, heres my take on all this. I took my car in December of last year to a GM Mechanic cause it was stumbling and missing like ae420gd is talkin bout.

anyway, i pull up to the dealer, and pull into the service area, tech walks out, looks at the car, asks me what its doing, i volunteer everything, and ask him his stance on perf. parts, well he tells me he likes em, and puts them in his car, hes all for speed and stuff, so i divulge my mods. he looks at me for a second, and then asks how long since i did all this, i tell him like two years, and he sighed and looked happy and laughed and said "glad you arent one of those kids who put parts on, do it wrong, then come to me and say, my car doesnt work right, somethings wrong with the motor!"

anyway, he took me into the service area (im surprised, usually GM wont let you accompany the techs into the service area) puts my car up on the lift, and talks to me while he is doing it (he drove the car back there and was playing with the clutch) he keeps telling me about how he pushed the clutch in and the cars rpms fluctuated, and it shouldn't do that, i was like, no kidding..

so once the car is in teh air, he inspects the front of the engine..and then he takes out a large screwdriver, about a foot long, by an inch wide, puts it between the balancer and the block, and pushes back towards the block...

to my amazement, the balancer/crank pulley moves OUTWARD 1/2"!! (holy $h!t - tolerance is .083")

i was amazed and saddened..he told me i had "crank walk" - where the crankshaft was sliding in and out of the block cause the thrust bearing was worn, and that it was caused by (cause i told him how i drive) my excessively holding the car at idle for long periods of time..

he says that there was another person who had this problem before me, and he did the same thing (holding the clutch in) as i did, and they ended up having to replace his crank because it was toasted, i didn't understand why till later, but on the 3.4L (not sure if this is the same for the 2.8,3.1) the third main cap has an INTEGRATED thrust bearing (learned from my friend the ex-GM lube tech) and this strengthens it. i wonder if the crank is made of bad material, or the setup they have is just too strong...whichever, do a simple test, this wont hurt the car at all, park it, turn it off, open the hood, take a large screwdriver and insert it between your balancer/crank pulley (large wheel at bottom) and the block, and try to move it, if it pulls out, consider getting the thrust bearing/crankshaft replaced.

just thought i'd let you know.

-Russell

p.s. its interesting, he's discovered and he still doesnt give up - (on MustangMike) when are you going to learn Kyle?

 

Actually, all the 2.8's (even the pre-mid-85 ones with small journals) have the thrust surface on the 3rd main bearing. Instead of just the bearing itself, the bearing hangs on the side of the journal. It looks like a "U" where the other bearings look like a "_" ...

But that's interesting! Makes me glad I have a car with an auto tranny. So it was the clutch in/out that did it? Isn't that partly the fault of the throwout bearing?



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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

Quite Possible.

 

What you need to do is isolate what cylinder is the problem when its missing.

This is a little time consuming and frustrating if the problem comes and goes.

I recently had a 3800 come in with the same symptoms, while it was missing we checked out and found out the #4 was the problem.

Now you know what cyl., check all basics.

Compression was good, spark was good, and had good fuel pressure at the rail. We had no injector pulse on #4. (keep in mind all these tests have to be done while the car is acting up)

What we found was that after the computer warmed up, a circuit in the ECM itself would quit firing the #4 injector. I could have the car running while it was missing and give the ECM a "love tap" with the palm of my hand, and the car would start running fine.

I don't know if your F.I. is "batch fire" or not. If its not, this might be something to look at.

Just my $.02.



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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

R.I.P. #3
My favorite quote about D.E. "He can see air"

 

I actually figured out the problem. I had the digital egr removed, because it was cracked and a new one costs a fortune. My friend had welded up the hole left over in the exhaust manifold. The welding wasnt the greatest and exhaust was leaking from it. Because of this small amounts of air is also being drawn into the exhaust from this leak. The air leaking in has been playing games with my O2 sensor, causing all of these problems. Now comes the test, to buy a junkyard EGR with manifold and hope it runs fine.

 

It will.
You can use ANY FI V-6 (2.8/3.1/3.4) manifold. They are all the same. I know. I am using a 1995 3.4 manifold set up attached to my 1985 EGR system. Fits perfect!
I paid $10 for one at a pick a part. Found it on an engine on the ground. I believe the nuts are 10mm. Grab them, too. I paid about $20 for the exhaust gaskets (doughnut in manifold to exhaust pipe was $9 @ Pep Boys & set of block gaskets).

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Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA