1992 camaro 3.1 multiport. First off I've replaced the cap, rotor, plugs and wires. Fuel pressure regulator also. The car starts good. Sometimes it runs smooth when cold and then bad when it gets warm, other times it runs bad all the time. The car gets a miss/stumble and will even backfire through exhaust when you accelerate the throttle. It seems to be the #2 & #6 cylinders on the driver side. I can pull those plig wires while running and it doesn't change anything. I've done a compression test and all the cylinders come out good. I've checked fuel pressure cold, hot and running. I've checked the resistance on the injectors cold and hot both and they all show 13-14 ohms. I can't get a scanner to hook to the computer to see live data so I'm kinda just shooting in the dark at diagnostics. I've unplugged every sensor one at a time and nothing seems to help it. I know that's shade tree but sometimes if the ect sensor is bad then unplugging it will change sometimes. Any ideas?

 

I'm dealing with a studder problem as I type I'm about to change my injectors in a bit. Try changing out the icm. That's the main suspect in the misfire backfire case.

 

If your car is starting fine and will run OK cold, it sounds like the issue is heat related. Have you tested your ignition coil? ICMs can be tested at just about any autoparts store, pickup coils are very easy to test too- Go down to Reply #3 in this thread: https://www.thirdgen.org/forums/v6/7...ml#post6149573

 

Replaced all 6 injectors, coolant temp sensor, coil, Icm and pickup. Didn't help at all. It's got to now it runs bad all the time. I cannot get a scanner to link to it but I can't just keep throwing parts at it.

 

I've been experiencing the same thing you have. I have a thread on here also and you can see the amount of parts I have replaced. I'm down too basically 3 parts left, MAP, FPR, and ECM. I'm thinking it's probably the computer as most of the searches I have done where people have replaced every sensor ends up being the ECM.

When my car fires and starts up normally it runs like brand new (only has 39K original miles), then randomly it will just quit and when giving it the gas it stalls. Then other times if I start it it will stumble and hunt for the idle and stall if I stab the throttle.

I've replaced the:
Fuel Injectors
Fuel Pump
Fuel Filter
Coolant Temp Sensor
Oil Pressure Sensor
IAC valve
Cap/Rotor
Ign Pickup Coil
Ignition Control Module
Spark Plugs
TPS

All of the vacuum lines are good and connected

No codes displayed nor does anything turn up in diagnostic mode.