Lowbuck

I acquired a 3.1 camaro a few months ago and when I got the car it had a slight miss at highway speeds but on,y in overdrive, if I kicked it into drive the miss instantly went away. I drove the car for a while biding my time until I gathered everything necessary to swap in a 350 sbc that was given to me. I'm still a long way away from being able to perform the swap and my car is at the point I can't trust it to get me 3 miles down the road and back. I was driving down the road one day and noticed I lost power steering, the engine stalled when in a corner under hard braking. It did this a few times and finally died and wouldn't fire back up. i finally got it running again and back home and have one through a myriad of things trying to get it lined out. The car will usually start up and idle good for a while, usually once it gets warm is when the problems start. I can crack the throttle slightly and it misses pretty bad, drop it in gear and it urges forward and the engine tries to stall and many times will stall. Like I said most of the time it's ok until it warms up, sometimes it will act up when I first start the car. I've read a lot of posts of similar issues people have had with varying degrees of helpfulness. I believe in the scientific method and I'm a power sports service manager so I don't believe in throwing parts at the problem. The car had a few known issues that I tackled first to take the variables out of the equation.
First I had some awful coil wires, I pulled one and saw it jump spark all the way to the manifold. I also replaced plugs while I was at it.
Second I had some rotten vacuum line so I replaced all of it.
The protective coating on the wires connected to the egr solenoid was gone and the wires were touching. The car would load up sitting at a stop sign and you could smell raw gas bad. I separated them and coated them with liquid electrical tape to insulate them. That seemed to solve that problem.
I also had a broken knock sensor connector that was showing a code 43 or whatever the knock sensor code is.
Verified the coil is firing I just haven't gotten a spark tester to see how strong a spark it is.
I haven't verified timing but it runs very good up until it starts acting up so I don't feel like that's an issue.
My main concerns are the egr, icm, ecm, or the injectors.
I'm really leaning towards the icm I'm just wondering if there I should a way to test it on these cars, I know you can on the coil-in-cap style distributors but idk about these.
I'm just wondering if anyone has had this experience and point me in the right direction from here.
Any help would be appreciated.

Lowbuck

Update: I pulled the icm and took it to autozone to have it tested, they said it was ok but for 40 bucks I figured I would replace it anyways since it was already apart. The crazy thing is I took the car out and drove about 20 miles or so and it acted perfectly, no rough idle, no stalling. I pulled back into the driveway and it started lugging and spitting and sputtering like it was. I hooked a fuel pressure gauge to it again while it was good and hot and had 38-40 psi at idle which according to Haynes is acceptable. Could the fuel filter be clogging up on it and still show good fuel pressure? I haven't done a fuel flow test yet I'll try and do that tonight. I'm gonna check injectors resistance as well. And is there any way to test the ecm without just swapping it out?

Lowbuck

A little disappointed nobody had any advice to offer on my situation but for those of you that may be looking at this thread with similar problems I have resolved the issue. I was able to get my hands on a scan tool and ran the live data as the car was running. It showed the egr was not completing any cycle percentage and that no solenoids were opening. Went to autozone, bought an egr solenoid and voila good as new. Thought about changing it before but like I said I don't like throwing parts at a problem I like diagnosing things properly in hopes it will help me out further down the road.

DEVILPUP

I've had something close turned out I had a fuel injector going bad and would cause issues when car was warm ran fine when I would get for the first time that day


Took the intake off after drive back from the local parts store and put my meter on the injector 2 were bad. Also my o rings were about shot on all of them as well

Base91

iTrader: (1)

Totally have to start with the injectors. Check the resistance of each one. If any one is bad and they are old replace them all. Southbay has a good priced set. While you're at it check the vacuum line to the fuel pressure regulator. Pull it off and if you can smell gas in it then replace the diaphragm in the regulator. If the engine is all original it's likely worth doing those two things anyway so you don't have to pull the top off again. Then start checking the other components. Check the idle air control valve is all clean inside. Check the egr valve is clean and operational and not sticking open. Temp sensor. Check for vacuum leaks. But you have to have good injectors and regulator or the other stuff doesn't matter.

Lowbuck

I should have looked at injectors first but I did have to line out my plug wires since they were jumping spark and looked like the 4th of July under the hood in the dark. Also had vacuum lines literally just falling apart all over the place so I had to replace and rule those things out first. My injectors, which I checked as soon as I got it home from about a 20 minute drive to try and check resistance with them hot, all were within Haynes manual specs right around 12 volts I think. Egr ended up being the culprit and my buddy and myself kept saying the egr may be bad over and over burn never really figured out how to test it until his dad came up with an obd scan tool and saw that it wasn't opening. But since then I've sold the car, made about $700 bucks and ended up buying another 92 rs 305 5 spd high I'm about to tackle the floor pan in.