My '89 350 TPI has a pretty good miss at idle... especially when the motor is hot. When you drive down the road, it seems ok (maybe a slight miss now & then).

Is there a way to tell if the miss is caused by a fuel injector Vs. a valve?

I'm wanting to fix this problem asap, but I don't want to take the heads off if I don't need to.

Any info would be greatly appreciated!

Thank you.

P.S. I've looked for vaccuum leaks several times and found none.
Plugs, wires, cap, rotor have all been replaced within the
last few months.

 

Did u put a noid light, or a test light to all the injectors to see if they all had power? is there an SES light on at all?

 

I would do two simple tests. Unplug one injector at a time. If an injector is causing the problem, when you unplug the injectors, the engine will stumble until you unplug the bad one. When you unplug the bad injector, nothing will change. The other test to do is a compression test. If you have a burned valve causing your miss, you will have a low cylinder. If you get a low cylinder, don't forget to shoot some oil into the hole to see if pressure comes up. If compression comes up with oil, the problem is in the rings, if it doesn't come up, your problem is likely a burned valve.

 

vortec77,
I've had a SES light for a while... it only happens when the car is cold. If it warms up and I turn the engine off - then back on, the SES goes away. It's a code 32.

Regardless of whether the light is on or off, the miss still occurs.

I didn't put a light on the injectors... I would assume they all had power cause when you go down the road, you can accelerate pretty smoothly. (?)

Russ-So Cal,
Sorry to ask a dumb question, but do you unplug the injector when the car is off - then start it and see if it runs bad?
Will this hurt the motor in any way?

This may not be any help - but there isn't any smoke coming out of the exaust. It was my understanding that this would occur if a ring was bad?

Thanks again.

 

Code 32 is the EGR system. An EGR valve sticking open can easily cause all the problems you describe. Hesitation or stumble on acceleration, rough idle, lean misfires (an open EGR acts kind of like a bad vacuum leak.) I'd start there.

 

I did. I replaced the EGR valve (purchased from GM), Harness (purchased from GM), and solenoid (purchased from Autozone).

This still did not fix the code 32.

 

first make sure the ground straps are tight, on the rear of each cyl. head. and make sure to rule out an ignition problem, nine times out of ten , i get ignition problems. never fuel. check the module, pickup, cap, rotor ,make sure no plug wires are burned, a common problem with headers. if it all checks out , then check for fuel problems, beginning with the filter. check the inexpensive stuff first and go from there. check AFPR, injectors etc. good luck....tom

 

Pull the injector clips w/the car running one by one. That or get a noid light so you can actually see the light go on and off when the injector pulses.

 

Unhook the EGR, plug the line, and see if it doesn't help.

If you didn't specify that you wanted a Borg-Warner solenoid at AutoZone then you have a cheap one. If it came in a blue and white box label "G.P. Sorensen" then you can just about count on it being bad right out of the box. There's something causing that EGR code and I'll bet my lunch that it's the root of your running problem.