I know, I know there are a thousand posts out there with this topic but one thing is similiar in all them; there's no fix action.

I'm getting misfires in all cylinders. I've replaced and regapped the spark plugs multiple times; no change. Right now I'm running plain old copper plugs gapped at .030.

I don't think it's the coils, not on all cylinders. Same deal with injectors. So, what the heck could it be? I did a pressure test and I do have a leak. I just bought a new inlet because I'm pretty sure that's where my problem is. Could that be the cause of the misfires?

I'm also getting a whistling noise at a steady 25mph. It's pretty loud. I can hear it with my windows up and it's really obvious with the windows down. I even had a guy mention it to me who wasnt in the car. I've heard this could be a turbo problem.

I"m also running a Perrin pulley and lightweight flywheel (another speculative reason for misfire).

What do you guys think? I'm pretty tired of chasing this thing I'll tell you that. The car runs good although I can feel the miss every once in awhile, usually during decelleration.

 

It's either the flywheel/pulley combo or you may have a leak in the up-pipe. I've seen leaky up-pipes cause mis-fires in cyllinders 2+4.

 

ive had this happen to me!! i mean, what hasnt happened to me lol.

okay it could be:

Head gasket!

intercooler y pipe leak, or frontmount pipe leak!

up pipe gasket!


I havent had my flywheel and pulley throw me a misfire. and its a 9lb wheel.

 

I had this happen to me when I went from Iridium plugs to NGK's. When i went back to iridiums everything went back to normal.

 

Head gasket...gosh I hope not because they were just replaced 6k miles ago.

Frontmount pipe, maybe but I'm using t-bolt clamps and I torqured them down really well. My leak doesnt seem to be there its somewhere in the turbo/inlet area.

up pipe gasket? I'm assuming you mean the gasket at the turbo not the header? Or either or?

 

Ive heard a thousand variations of this although most say the iridiums make it worse. I think its whatever you had when you were tuned is what you need to stick with. In my case I had a stock plugs in there and thats what I have now and it seems to be better than iridiums or platinums.

I may try one step colder but I dont think that will work either.

 

i never figured out my misfire issue. it drove me insane. tried everything i could over the internet and still would get the CEL every couple weeks at idle.

good luck bro, i know alot of people who have never cured it.

tried all different types of plugs and gapping sizes
bought new injectors
new coil packs
checked for leaks- none
took the pulleys off

i tried all that and still got the code....

 

flywheel

 

i was using the stock flywheel..

i know someone with this issue on a bone stock STi. never been modded or raced.

 

Well, I'll keep everyone posted. I'm going to try

fix pressure problem
take a look at up pipe gaskets
one step colder plugs
retune

Heopfully one (or combination) of these will fix my problem.