ericdwong

OK I"m trying to diagnose a rough idle problem. I got a 0606 CEL on the other day which is a cyl 3 misfire. FYI the rear bank of cylinders goes 1, 3 and 5 from left to right if facing the motor. I pulled the plug and compared it to another, it was carbon fouled. This indicates rich mixture. So either the FI is stuck open or the coil isnt igniting the whole thing. So just for kicks I moved that plug to cylinder 5 and the coil to cylinder 1. I do not have a CEL on anymore, but my idle is rough.

So today, I bought a new spark plug to replace the carbon fouled one. It didnt do a darn thing. Idle is still rough.

This leaves me to believe it is 1 of 2 things. Its the coil or the fuel injector. Ive been reading about the coils and will probably borrow a friends to test. But my question is has anybody had a fuel injector go bad?

I CANT FIND my freakin multimeter anywhere and its p__ing me the F off.

paw-kz1k

Since you did not move the injector, if the same cylinder fouls-out again, its the injector.

Since you did swap coils, if the problem follows the coil, you could assume that coil is at fault.

To be sure, you need replace the fouled plug (which you did) and then drive it several days and then recheck it.

Anyway good luck chasing down the problem!

Paw

DUNKEE

do this, I just replaced two injectors since November. Just pull the clips off of all the injectors one by one, first the front three, and if the engine dosent drop in rpms, and sound like its going to die, then that is what is the problem, the injector, and it will tell you what one is bad. As for the back 3, just pull the clips off one by one off of the spark plug harness. The import guy here said that if you pull off the spark plug harness in the rear of the manifold it controls the pulse through the plug(cuz the other injectors are under the manifold) so If it does the same thing with the idle, not dropping, then that is the injector that is bad.
I had that problem, it felt like there was a ruff idle, and I could even here the misfire in the exhaust going"pop,pop" so I took it to him, and he pulled the number one injector, and the engines idle never dropped, so he told me that was the one, and sure enough it was the ruff idle went away
I noticed at about 3K rpms, that there was still a little ruff idle, but more so, it sounded like a grinding. So I took off the plug harness, and the check engine light came on, but the engines idle didnt drop. So I took it to him, he hook up a computer, and I forgot the code that it threw out, but I looked it up in the Chiltons book, and it said somthing about the ignition firing. He told me that he looked it up also, and said it was another injector. I just had it replaced the other day, and there is no more knocking, and smooth idle.
To make a long story short, just pull off the front three clips one by one, and then reclip them. Then do the back three one by one, and clip them. Which ever one dosent cause the engines idle to NOT drop that is the culprit.
Good luck

Quicksilver

iTrader: (1)

Sorry about your Vette dude. RWD performance cars can be dicey in bad road conditions.

ericdwong

OK I tried to pull the coil pack but all of them did it so that means all of them work- or at least they partially work. Hmmm.

Would a stuck open fuel injector cause rough idle?

nobel

ericdwong, so did u fix the problem? I too am having this problem and have spent several hours tonight diagnosing the problem and I've narrowed it down to a possible bad ignition coil. What I did was pull the harness off of each ignition coil one by one and whichever one did NOT result in engine running rougher than it currently is could mean a POTENTIAL bad coil. SO that is what I did and coil #6 which i pulled the harness out did not result in the engine running rougher. So what I did was move that coil over to #4 spot and while the engine was running, i pulled the harness.....engine roughness did not change......which means i've more than likely isolated the problem down to this coil. However, it doesn't mean that the coil has 100% failed b/c when i plugged the harness back in, i noticed that the engine began to run smooth again. Thats weird b/c when i pulled the plug, the engine did not run rougher, but when i plugged it back in, engine sounded much much better. I sat in the car and revved it a few times.......it was smooth as silk. I've changed all 6 spark plugs so I've pretty much eliminated that as a possible problem. What are the chances it could be a bad harness connector to each coil? (my 2-cents tell me that is highly unlikely) Has anyone here experienced any problems with the harness connector to each coil, and not the coil itself?

If you've read down this far, then what i'm trying to say is that the ignition coil which i suspect is bad has not failed 100%, i can't given a percentage on its failure but everytime i pretty much drive the vehicle, it triggers my SLIP/TCS light to come on which produces terribly rough idle. I will check the fuel injectors tomorrow, lets hope its not that.