Hey all,
Browsed through some posts that seem like a similar problem, but no resolution was posted.
I have a '97 Malibu with the 2.4l motor.
Bought it from a guy who did not care for the car at all.
So, changed pretty much all of the gaskets... head, cam to head, etc...
Fresh oil change.
New fuel filter.
New air filter.
New plugs.
New air inlet sensor.
New IAC valve.
New ignition control module.
Cleaned the hell out of all components: throttle body, valves, head, etc.
Ran seafoam through the brake booster, and have some in the oil and gas right now.
Resistance checks through the ignition coils are assumed good. (I measured them and they were both the same.) The resistances were even for both coils. The spark plug boots look a little melted, but I think that's from a previous overheating problem. Engine no longer overheats. The conductors appear to be in good condition though.
Problem still persists: low and stumbling idle with motor hot or cold. Don't remember what code it is, but it's random cylinder misfire. The car drives great, but then again when I got it it didn't run at all. The only obvious problem is the idle.
Any help is appreciated.
Thanks!

what did you clean the throttle body with, i hope you did not use the old type spray carb cleaner. So you replaced the maf and the iac ? what did you gap the plugs at ? this is the 4 cylinder engine , right ? If the car is throwing codes you need to address each code. The PCM processes info from all the sensors to determine the right air / fuel mixture as you probably know already. It may come down to hooking a scan tool up. what about the injectors ? have you checked the simple stuff, like fuel pressure, the functioning of the fuel regulator, i just reread your post,,, get new plug wires.
if you have random misfires, too me that would eliminate the engine, unless all 4 cylinders had the same defect. it is more likely weak spark or lean or fat fueling. Maybe the iac is not seating corrctly or is stepping out too far or nat far enough.

what did you clean the throttle body with, i hope you did not use the old type spray carb cleaner.
Autozone throttle body cleaner
So you replaced the maf and the iac ? what did you gap the plugs at ?
Gapped as per Hayne's
this is the 4 cylinder engine , right ? If the car is throwing codes you need to address each code. The PCM processes info from all the sensors to determine the right air / fuel mixture as you probably know already. It may come down to hooking a scan tool up.
replaced all sensors called on the pcm scan. It's all down to the random misfire.
what about the injectors ? have you checked the simple stuff, like fuel pressure, the functioning of the fuel regulator
How do you check the injectors? I know this is grossly unsafe, but I was thinking about pulling the fuel rail and pointing the injectors out away from the car and turning the key to see if all of them are spraying. Any tips, tricks, or known procedures preferably would be appreciated.
i just reread your post,,, get new plug wires.
This car doesn't have plug wires. It's all one assembly: ICM and coils mount direct to the plugs. It sux.
if you have random misfires, too me that would eliminate the engine, unless all 4 cylinders had the same defect. it is more likely weak spark or lean or fat fueling. Maybe the iac is not seating corrctly or is stepping out too far or nat far enough.
IAC seems to be doing it's job. Pulled it out and turned the key, it extends and retracts as advertised in the "how to check" in Hayne's.

I was thinking about pulling the fuel rail and pointing the injectors out away from the car and turning the key to see if all of them are spraying. Any tips, tricks, or known procedures preferably would be appreciated.
It might make a good video to upload to one of those web sites.:grinyes: Will the injectors stay in the rails ? that could be up to 50 lbs of gas behind those, :nono: what are the codes ?

i kind of doubt it is the injectore, random misfire, they would all have to be bad. It is something that is comon to all. Overhead cam ? did you get the cam timed right ?

It might make a good video to upload to one of those web sites.:grinyes: Will the injectors stay in the rails ? that could be up to 50 lbs of gas behind those, :nono: what are the codes ?
:lol: it was just a fleeting thought. That would just be asking for trouble.

i kind of doubt it is the injectore, random misfire, they would all have to be bad. It is something that is comon to all. Overhead cam ? did you get the cam timed right ?
That's one concern... I re-assembled just like the book said. All my marks ended up right, but that's not to say that it was timed right in the first place. Any tips on how to make sure it's right?

Replace the sparkplug connectors.

Replace the sparkplug connectors.
What, just those little boots?

I duno about the 2.4L, the 3.4L has a crank position sensor, used for timing. That might cause a misfire.

I duno about the 2.4L, the 3.4L has a crank position sensor, used for timing. That might cause a misfire.
ew, that sounds fun. lol
Know any way to check it before removal / replacement?

What, just those little boots?

The boot and spring assy that connects the coil to the plug can be purchased without having to buy the coil assy. Google will show them.