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cylinder 4 misfire

9K views 6 replies 4 participants last post by  tehfuzz 
#1 ·
Hi all,

I am particularly stumped when I am getting reoccuring cel's being thrown with my 08 wrx. I had my intake gaskets both upper and lower replaced at the dealership that was still under warranty and had one of my injector o-rings replaced as well too among some other things that were under warranty. It was fine for a while drove it for a good stretch now the cel is coming back. before i was getting p0301 cyl 1 misfire. When the dealership did the maintenance that one went away.

This time cyl 4 codes are being read from my plx kiwi that i keep in my car. I went and replaced the spark plugs with some brand new OEM iridiums. Seem to fix the problem for the next ~700 miles. Now I seem to be back at square one.

The biggest clues I can give before people start mentioning the compression test is that the CEL only triggers when I am idling when i am at a stop light or letting it warm up. I brought it to a friends when we changed the spark plugs, and while i was out getting some new ones he tested cylinder 2 and 4 and said that they both checked out. The car has no loss in power and does not struggle to get going at all. The gas mileage has not been affected either.

Wouldn't be surprised if the gaskets cracked again, but I think its time to call the dealer again.

Wondering if anyone else has had a similar problem or not. Subaru's sure are finicky little buggers.

Thanks for checking this thread out and I will appreciate any advice that is shared.

Cheers.
 
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#4 ·
Do you have access to a scan tool? If so, could you please tell me your LTFT and STFT at idle, 1500rpm, and 2500rpm?

When I did this, I had a negative LTFT % at idle only, meaning the computer was trying to lean out the fuel mixture. So for me, it turned out to be a leaking fuel pressure regulator, a stuck Purge Control Valve, and improperly gapped plugs.
 
#5 ·
I know this is a belated update to the situation. Those who are members of MNsubaru have heard this tale already as I am an active member on that board. I live and learned by bring the subaru into the stealership for further diagnosis. From there on I had a long battled dispute with them and subaru regarding my warranty which was denied since my ecu was flashed.

The first time I had my subaru in for service the upper and lower intake gaskets were replaced since some had cracks. However, I later learned that it was not the source to the problem that was discovered. Six months had passed and it was still having the same symptoms. CEL's would come and go.

I brought it back into the shop had them pull the engine and run a diagnostic test. Had them do a compression test, and found a 10% compression loss in cylinder four. Also all of my exhaust valves had been burned, rods had been warped, and the heads needed some work. (Not uncommon for a turbo'ed subaru... :) )

After heckling with SOA and the dealership I did manage to get some discounts since my warranty was denied. Mind you I had the car for 10k miles after the initial purchase of this CPO car which was not beaten on.

The best news was yet to come when my car sat on the lot for about a month since I had a motorcycle to ride for the summer. I received a phone call that my car had been broken into and my stereo had been stolen with some excessive body damage that came out to be around $1200 dollars in insurance repairs.

Good news is that the car is fixed on both levels, and is running just fine. I learned my lesson especially about taking my car to the stealership.
 
#7 ·
Right?!

The SOA inspector only saw that my ecu was flashed and supporting mods, but could not pinpoint that modifications were the cause of failure. mechanic at dealership mentioned failure with burned exhaust valves can happen on any stock 2.5 motor...
 
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