My boss has a '97 Camaro with the 3800, and had a problem with a very rough idle. He says that the SES light flashes at idle, but once he gets to 1200rpms, the light stops and the engine is pretty smooth.

Apparently he had the code read and found it was a misfire, and narrowed it down to one cylinder. He pulled the plug and it was burned up badly (electrode almost completely burned off).

My theory is that a bad injector is causing a severe lean condition, but that doesn't explain why it would go away at higher rpm's. Could this just be 'masking' the problem?

 

I'd start with a quick compression test on that cylidner to ensure that part of the story is OK.. if so and you don't hear any low end knock out the engine it could just be that injector

geuss the sure way to tell is to just swap that injector with a known good one from an a diffreecnt cylidner and see if the SES code moves to that cylinder

 

Edit: today I can't read/type at all
Replace plug together with injector. How many miles on that burned plug BTW?

 

I would start by putting in a fresh plug and seeing if the problem persists. With the Delco plat plugs, it isn't uncommon for the pucks to fall off creating almost a double sized gap. If the misfire comes back, then I would troubleshoot further. As mentioned above, do a compression test and see if that cylinder is within spec of the others. Also, he could swap an injector from one cylinder to a known working cylinder and then see if the misfire follows to that cylinder, then you'll know if you have a injector related issue.

 

Well, I've never replaced injectors before, so...how hard of a job is that. I know he is pretty competent. Is that something that can be done relatively easily?


EDIT: Also, what will a compression test tell me? I would think if I burned the plug that there is definitely compression. Also, I think the plug was new, and shortly thereafter was pulled and burned.

 

Injector swaps are a relatively straight forward job. A compression test will determine if there is a mechanical related fault on that particular cylinder.

 

the injector swap is really not hard to do at all.. the fuel rail is held down by two little nuts that you need to losen to get the injectors out... one thing I found to help was to wait to get the actual injector lose from the fuel rail and intake before pulling of the injector wiring clip as the wiring clip has a little metal clamp holding it in place and that is much easier to remove if you can have the injector free


p.s. like said noted above the compression test and color of the plug you take out will help you determine if your problem is mechanical on the engine or something external (bad spark, fuel etc.,).. most likely the problem is something external but the compression test is something that is easy to do and I just say it is good to starting point since it is easy to do and doesn't cost anything as when you start swapping parts and whatnot to diagnose a problem the costs can pile up but that’s just my 0.2

 

Thanks for all the replies. I have passed it all on to my boss. If he ever comes to a solution, I will gladly let you know.

I was actually kinda hoping he would ask me to take a look at it, since it's his daughter's car, but no luck as of yet.