Thread: Misfire cylinder 4

My car has a misfire on cylinder 4. Here's whats been done or replaced: Plugs(twice),wires(switched around and still misses only cyl 4)injectors (swtiched around ,still misses cyl 4) fuel filter was checked and replaced(old one was fine),heads were off and resurfaced/magnafluxed, new head gaskets etc,replaced pcm with a new one(still misfires on 4,switched ICM (twice and still misses),replaced and switched coils(twice and still misses on 4) Cam position sensor replaced and still misses, fuel pressure is fine,(misfire goes away or at least seems to upon normal driving),vacuum lines all check out fine,.... I'm extremely close to dumping this car. I've got 11 thousand tied up in it from the time I bought it a year ago august til now..... Any help would or insight would be appreciated. The car is sitting at a shop right now and I've basically told them they can have it until they find would could be going on....

Scan it.

That's what you need to get off of it.

What info do you want? I scanned at thats all that comes up is the misfire on cylinder 4 and its idle only at this point

Like a tuner scan.

Like an aeroforce scan.

Something that tells us something.

I'll see what I can do since its at the shop.

COMPRESSION TEST!

Sent from my Droid

Have you done a compression/leak down test?

Bam, double post winning.

Yes. There was a test done earlier this summer. Showed 70-80 psi in cylinder 4. This is why I tore everything down again and had the heads gone through. It was determined that the heads needed resurfacing etc. After all that was done , I checked the pistons,block etc and it was fine. Everything was put back together and I had another compression test done and all 6 cylinders were perfect. I have heard of rare occasions of cam lobes being worn or w/e and causing issues like this ...

When does it miss? Idle? Under load? I would do another compression and leakdown test. Does it use any oil?

Sent from my Droid

Just misses at idle. Goes away under load or driving... The latest compression test was performed monday and all was fine

oh yeah no oil loss either. This was an L32 swap and the motor basically has less than 600 miles on it since the guy built it.

Originally Posted by RamairGTP2

Just misses at idle. Goes away under load or driving... The latest compression test was performed monday and all was fine

This is a classic symptom of low compression.

Sent from my Droid

sympton yes but all the cylinders are right where they're supposed to be.

Took the car out today from the shop.... Used the scanner and watched all the numbers.... Spark was between 30-40 under normal load/speed, one random multiple misfire showed up when I got back from driving(car was idling) cylinder 1,3 and 4 then back to cylinder 4 for misfire..... Absolutely zero misfires when driving.. only 4 began to misfire when letting off the gas or idle.... Fuel trims were perfect and all other sensors were functioning as they should....

Pretty odd.. consider trying an ICM.