Cyl. 4 misfire

Ray

Ray

The Northernah'
Getting the cyl. 4 misfire code on an 03 Wrx. Cleaned MAF, going to do a compression check. After that what's the most common thing to check. I've read lots of threads listing tons of things.

So what I'm asking is in your experience what's caused it.

 
If you have a scan tool where you can watch the misfire id say swap coils and see if it moves.

Swap plugs... See if it moves.

Potentially swap injectors.... Same as above.

Check compression

Leak down test.

New heads or block

 
Thanks Matt that's what I was thinking of doing. I've got use of an accessport to keep reading. I've got extra coils, injectors and plugs to use.

 
Last edited by a moderator:
if theres a noticable skip and you can hear a dead cyl when cranking theres a good chance you have a burn exhaust valve on that cylinder

 
thanks mike, compression test soon to come
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So I've noticed that the car doesn't do it in first, or if I climb through the rpms slowly. Still need to do a comp. check

 
So without a load it doesn't misfire or it's subtle enough not to notice.

I'd check the compression and do a leak down to determine if the motors junk regardless.

 
Ok a little backstory. Mid October a coil pack came loose and completely came out while I was driving. Obviously I fixed it on the side if the road a the car was running like poo. Now that I look at which cylinder that was...it was cylinder 4. And I haven't reset the codes since then because I pulled te bulb due to stupid evap codes. So I'm guessing that's where my misfire code has come from and why since I reset it 3 days ago it hasent come back.

May have jumped te fun in assuming its a misfire. Sorry folks

 
Lol. Scan the code sir!! If the coil pack managed to come loose it's possible the plug could back off as well. But scan the code and report back.

 
Compression test results:

(Drumroll please)

Cylinder

1-130

2-137

3-140

4-139

Great news! So I went onto checking the plugs, all were good, then Kenny had a spare set of coil packs kickin around so we threw them on and she runs like new again!!

 
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