Hey everybody! Thanks for all your previous help. Here's my problem. My car will start, but it won't idle without stalling. It'll stay running as long as it's kept at a high rpm. Once it's warmed up, it will idle and when you step on the gas it hesitates. I replaced the fuel filter and that didn't fix it. I took it to a shop and they said that the prom and ECM were bad. So, I replaced those and that didn't do it. It's in another shop right now and the only thing that's coming out on their scopes is a lean condition from the computer. They don't know what's wrong with it. Does anybody have any ideas?

86 Camaro 305 TPI VIN F

Any help would be appreciated...please...I'm desperate!


Thanks,
Travis

 

check your tune up make sure it's good, scan for codes and operating data, check for vacuum leaks

 

Ideas? Yes. Find some other shops, or start performing the diagnosis yourself. The shop that suggested the ECM and PROM should be permanently be removed from your list.

The shop that scanned and revealed a lean condition should have done some more investigation. Lean is normal on cold startup, since the AIR sytem is pumping excess air to the exhaust manifolds during warmup.

Follow Ed's advice. As part of that tune-up, test the fuel pressure.

 

I definitely took my car to a different shop. That first just rips people off. I didn't think it was the ECM, but I replaced it away(I should've know better).

I don't know how good this info is because it was from the first shop, but they showed me all of there scope info and it look like everything was coming out fine, good vacume, timing, voltage, etc...

The shop I have it at now said it has good fuel pressure. And the're getting the lean condition once it is warmed up as well.

I haven't done a tune up on it in a while because I'm up here at school and I don't have any of my tools(I feel so alone with out them). Should I just start with doing a tune up on it?

I should also add that it was running great the night before I started having this problem and I started it up the next morning and then it didn't.

If a tune up doesn't work, does this sound like it could be an EGR problem?

Thanks,
Travis

 

It wouldn't hurt to test the fuel injectors.

 

Vacuum leak sounds good. I had a similar problem not long ago. I assumed it was a vacuum leak and proceeded to replace my tubes, and manifold gasket. ..... It ended up being the Idle Air Control Valve. (Screws in on the passenger side of the throttle body)

 

Start looking for vacuum leaks before you start replacing parts. Thats what your problem sounds like. Your engine is pumping air out a leak and the ECM is trying to correct for it. Gaskets do go bad on these cars (old age).

 

Would the Idle Air Control Valve make it stall after it is warm?

Thanks,
Travis

 

Well the second shop had no idea what is wrong with. They told me to take to GM, they also have no idea what is wrong with.

Also, they tried a new ECM and PROM and they said it fixed a code 23, should I tell them to put back in the old one?

It was running perfect, then the next morning it didn't.

Also, they said there is no vacum leaks.

Anyone have any ideas, I don't want to pay them any more money.

Thanks,
Travis

 

Cold air start valve , Idle air control valve?

The hesitation sounds like dirty injectors ... tried spraying injector cleaner in the intake?

Also if you havn't already, buy the Haynes repair book .. it is the bible. It tells you how to check the engine codes and what they mean.

 

Ok...I had at gm for about three weeks now and they don't know what the hell is wrong with it.

After the first shop I took it to, I replaced the ECM(from NAPA) and the PROM(from gm).

GM tried using a gm computer and that didn't fix it. Now they are trying to say that napa gave me the wrong computer(i know i checked the #s before i left napa) and they ordered the computer with the matching #s as the one that i bought from napa. They say that there is two different computers for my car.

They don't know which one goes with my car!!!

I know this isn't a computer problem, but they won't buy it. They told me today that they ordered the other computer and are going to try it.

Anybody have any ideas on how to bitch at them so I don't have pay for all this crap once they get the other computer and discover that it doesn't work?

Thanks,
Travis

 

Check the IAC motor, make sure the screw hasn't been turned or played with. Also check the throttle position sensor. Make sure the computer the bad shop gave you is the right one. GM compuetrs will let the wrong car run sometimes.

 

Well got my car back from gm...they spent 12 hrs on it and couldn't figure out what was wrong with it. I replaced the IAC and the temp sensor(the one for the computer) It still has the same problem. It seems like a vacum leak but they couldn't find any and it is getting good vacum pressure.

So...when I start it up it stalls unless i step on the gas, but when i do step on the gas the rpms drop dramatically (so much so that the car almost dies) and when i let go, the rpms suddenly increase. In other words, it won't idle and is essentially doing the opposite of what it should be. This is only when cold.

Now once it is warmed up it idles fine. but it will hardly go when i press the gas. it backfires when warm and cold. I can even floor it and it will only go to about 2000rpms. Then after a few seconds, it will pick up.

I tried driving my car at 55 mph and it could barely maintain speed and while driving, it would jolt consitently, back and forth. This was especially apparent while going uphill.

And just a reminder...this problem occurred overnight, which sounds to me like an electrical problem. It ran perfectly (no stalling or hesitation) the night before I started it and discovered there was something seriously wrong. Can a gasket go bad overnight??? Somebody please help me...i've been without a car for about 3 months now and i'm getting sick of bumming rides.

Travis

 

Can you get back your original ECM and chip? That's gotta be worked out first.

Check fuel press.

Check TPS voltage thru it's entire range of motion. It's best to check it with a scope so electrical noise can be seen. ECMs hate noise. An voltmeter will work, but not as well.

 

No, i can't get back my old ecm, there was a core charge on it. And i can't find the old prom.

All of the shops said it had good fuel press. And gm checked the fuel regulater and it was good.

I will check the TPS voltage.

Thanks,
Travis

 

o2 sensor ($18), fuel injectors?

 

Well I checked the voltage with a DVM on the TPS and it is ok through the entre range. Car still doesn't work.

Are the O2 sensor values used when the engine is cold?

What sensors are used by the ecm when the engine is cold?

Thanks,
Travis

 

this might be a long shot but could the catalytic convertor maybe be plugged?

 

The cat was emptied out before i got it.

travis

 

The O2 sensor voltage is not used until ECM enters closed loop mode. All the other sensors work when eng is cold.

If you can get your hands on a scanner or use a laptop with an interface cable, that would be the way to go.

What voltage did you read on the TPS at idle?

 

The TPS read .55 v at idle(key on, ign off)

How well does the winaldl work? And will it work for my ecm #1221765

Travis

 

Sounds like an airflow meter to me... seeing as you have already checked the vacuum lines (have you really? DO IT AGAIN YOURSELF! Go out to AutoZone and buy a $21 Mity Vac vacuum pump and hook it up to one of the main vacuum lines. The book that comes with the pump tells you just what vacuum you're engine is supposed to have. Replace the lines if you need to, they don't cost more than $15) replaced the IAC (have you had the ports cleaned?) and checked the TPS voltage. Also, have your ignition module checked or replace it. Sounds a little bit like that is on the fritz.

The ECM is usually the LAST thing you should replace if the problems don't go away, not the first. That shop really ripped you off there. And next tiem you decide to replace it, keep the factory PROM (very important!) and buy a reman or used/working GM unit. Many of those A1Cardone units I have heard are bad, and I think that is what my bad one is...

 

Now I'm getting a code 44...

By airflow meter do you mean the MAF? How do I go about testing it? I will check the ignition module. I'm also going to test the vacuum again(this time I will check it), once I get a pump.

Thanks,
Travis

 

If you unplug the MAF (I was not sure of which you had because it's a V8 and mine's a 6) and the engine runs fine, it is either MAF relay or the sensor itself.

And, according to my Haynes junk repair manual, a code 44 can mean you have a bad ECM, O2 sensor, malfunctioning fuel injection system, bad MAF, or a .... vacuum leak.

And don't forget to keep the Mity Vac for when you need it later. It also helps to bleed the brakes and test things like the EGR valve and vacuum diaphragms in the HVAC system, among others.

 

MAF or MAF relay. Try swapping the relays first, reset the computer and try.

 

My car did the same thing, and it was the MAF sensor.

 

44 is most likely o2 sensor malfunction or a fuel delivery problem(Haynes manual...and other sources). I'm having this fun myself. Exact symptoms.

I think I have finally traced mine down to rust/trash in the tank stopping up the sock on the fuel pump.(car sat for a rather long time with no fuel cap)

Since you seem to have good fuel pressure normally and all sensors are operating within specs(GM collaborated), and it happened rather suddenly....do you suppose someone may have sabotaged your tank?

I don't mean to insinuate anything....just something to think about.

 

Well, I disconnected the MAF sensor and the car ran better. So, I replaced the relays...didn't help. Got a new MAF sensor (Wells SU145) and now my car won't even start. It turns over, but nothing else. When I disconnect the new sensor...same thing. Please help me, I'm completely stumped.

Also, if the fuel pump was clogged up, would there still be good fuel press?

I'm going to an ignition module and see if that does the trick.

Travis

 

Check the MAF wiring, especially the signal wire to the ECM. Remove the ignition module and have it tested at AutoZone or someplace like that before you go ahaead and buy a new one-they aren't cheap by any means.

When was the last time the fuel filter was even seen, much less changed? You might try changing it or checking its orientation (it only goes one way and is marked as such).

 

How do I check the wiring for the maf?

The fuel filter was changed at the second shop, and I have gone through half a tank of gas since then.

 

i have many of the same symptoms on my car that has a carb on it. I cant beleive no one at the shops could figure it out for ya. I hope mine gets fixed soon. Although i beleive mine is running rich so...For yours it does sound like a timing issue that went unnoticed even though it checked out fine.

 

You might ask around for the answer to the MAF problem. Someone on here has a troubleshooting guide for all of the computer controls and sensors, but I can't remember who it is-they helped me diagnose my ECM as the main problem behind my code 54... what a pain.

And just because a shop put the filter in for you doesn't mean they did it right. Check and see. There is an arrow on the filter that is supposed to point at the line going TO THE ENGINE, not to the fuel tank.

 

I just notice my TPS sensor seems to be what is causing my drivability problems for the last few yrs. By finally throwing a low TPs voltage code. I can actually watch my TPS sensor vary the voltage as i cruise at low throttle angles ~.8 volts or 15-20% throttle. The TPS was changing from 0.0 volts up to correct .8 volts almost like an O2 sensor does. I'm almost positive this is what causes my car to stumble at cruise and sometimes chooses not to idle.

Might be worth it to just get a new one or get one from a junkyard to try out. I actually switched from MAF to MAP b/c of this.

 

I finally got it all fixed. The reason it wasn't starting was because of fouled plugs.

I don't know if the MAF sensor fixed the first problem or not, because after I started it up it ran better then it was but then I got a code 33....

To get rid of the code, found out that the computer wasn't grounded. Now it all good.....thanks everyone!