NOLAGG

iTrader: (1)

In a nut shell I get the cylinder misfire code twice and it comes and goes on it's own randomly . Sometimes stays for a few days then goes away for a while then appears again out of nowhere ? I recently changed the plug which seemed to look normal no oil/ gas on it , switched coil packs and also have a compression test which read 155 psi. The car is a 2003 6 speed gt with 92,000 miles . Can anyone give me any ther ideas on what it may be please ? I also ran some fuel injector cleaner threw it and nothing . Any other suggestions would really help . Thank you

NOLAGG

iTrader: (1)

Any body ? Suggestions/ ideas ?

sradenton

iTrader: (19)

If you've changed spark plugs and switch coil pack. Might need to checked that injector? and how Are you clearing the codes?

NOLAGG

iTrader: (1)

Haven't been clearing then , it comes and goes on it's own . Last time I cleared them was about a month ago and did the pedal reset but they came back its showing cylinder 2 misfire twice on the " autozone scanner . You think the injector is faulty ? I tried some injector cleaner about 2 months ago and nothing .

sradenton

iTrader: (19)

You've changed spark plugs and the problem code still comes on, then you switched #2 coil pack and the code still pops up with #2 misfire. A faulty injector could also cause this problem and also make sure your workout the problem with the right cylinder. are you 100% sure the code was #2 before and after coil switch?

NOLAGG

iTrader: (1)

Yes sir , 100%..... I have been to autozone like 5 times and the same code pops up twice . I was told possibly the valve cover due to the insulators around the spark plug going bad but there's not a drop of oil in sight . So I know that's not it either .... The compression is good spark plug and coil checked out fine . I'm stuck and hate to see the light pop up and have to drive it like that .

I don't know if this has anything to do with it but sometimes at idle after driving for a little whether light on or off I hear the car make a weird noise like its coming from the bottom end almost like some ones knocking on the block maybe a miss or somthing but this only happens sometimes other then that the car runs and pulls excellent compared to other z's I've driven . It's hard to record the noise because of the engine running but I person you hear it clearly especially in the cabin .

NOLAGG

iTrader: (1)

Any other comments ?

Touge Z

iTrader: (3)

have you figured out the problem?

Dimeback_Z33

sry to bring this back up but im in the same boat and have done exactly everything youve done, and my code to comes and goes even after all that, were you able to figure out the problem?

zakmartin

If the misfire occurs at idle, it could be a vacuum leak. You can do a test using carb cleaner or propane to find the source of the leak. There are several videos on Youtube that show you how to do this.

If the misfire is occuring when the engine is under load, a simple way to narrow down the issue would be to swap the coil pack and fuel injector with another cylinder. Call the known bad cylinder "known bad" and the known good cylinder "known good". If the misfires go to the known good cylinder, then you can rule out a mechanical problem with the known bad one. Now return the coil packs to thier original places. If the misfires go back to where they started, then your coil pack is most likely the issue. You can check the voltage output of the known bad coil using something like a Thexton THE458 Spark Tester just to be sure. If the misfires stay at the known good cylinder, then the fuel injector is the issue. You can either clean the injector or replace it. Pouring injector cleaner in your tank will sometimes make matters worse, since crud from your gas tank will come loose and work its way to your injectors. Injectors need to be cleaned under pressure with a special solvent and an electronic trigger.

There are other ways to test the components that cause a misfire, but this way doesn't require any special (expensive) testing equipment. When I'm looking for a misfire, I use a two channel automotive scope and do a relative compression test to nail down the known good and known bad components. A four channel automotive scope works even better, but I don't have one of those.