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-   -   Need advice on my WRX. Heres the situation P304; Rough idle; Cyl 4 @ 90; (http://www.wrxtuners.com/forums/f72/need-advice-my-wrx-heres-situation-p304-rough-idle-cyl-4-90-a-33456/)

2002SilverSedan 01-06-2013 01:16 PM

Need advice on my WRX. Heres the situation P304; Rough idle; Cyl 4 @ 90;
 
Please give me your thoughts on whether I should fix or get rid of my 2002 WRX with 128k. I brought it to the dealership and here's what they told me:[INDENT]
Road test vehicle. Utilize select monitor to diagnose condition, found misfire on #2 and #4 cylinders, removed coil and plugs to perform compression test. Found #2 cylinder at 115 and #4 low at 90. Possible burned valve or damaged piston.
Would need to take engine apart for further diagnosis and estimate.[/INDENT]
The mechanic told me that it would cost some where between 2500 - 5000 to repair the issue depending on exactly what needs to be done.
Which do you think is more likely? Should I get another opinion? If not what should i do with the car? Any idea how much the car is worth in its current condition? Note, its doesn't have any dents or anything.

Also I wanted to mention that my car first started throwing the CEL code P304 about a year ago but after spending a fair amount of money trying to fix the issue via replacing the plugs, coil, fuel injector, and motorvac carbonclean service, my mechanic indicated that the compression in the 4th cyl was fine and that the CEL was to be ignored until it got worse or proved to be a false alarm. Over the past couple months the P304 got more frequent until I brought the car in last sat.

detrails01 01-06-2013 08:43 PM

That is fairly low compression for those cylinders, but 115 and even 90 I dont believe would be low enough to misfire? is the engine missing when you hit the gas? I would start by switching a good coil for a bad coil and seeing if the scan results are the same. (if you have a scan tool) if they are then you can probably rule out a coil. I would also check injector resistance. you can also determine whats causing a misfire by looking at fuel trim but i dont know if you have access to a scanner like that. Honestly, i just dont believe a cylinder with 115 psi would cause a misfire unless its not getting proper spark or fuel.

Hope this helps

2002SilverSedan 01-07-2013 03:50 AM

Yah unfortunately I don't have access to a scanner or a bad coil. However, the coil was replaced 1 yr ago so it seems unlikely that its the culprit. Same goes for the injector in cyc4. Regarding the misfires, I believe it will misfire if Im in neutral and i blip the throttle but I'm only aware of them due to the CEL as I don't hear or feel anything on occurrance. With that said the idel is really rough.
The dealership indicated that best case the repair would cost 2500 (I guess that would be the burnt vavle case) but im just wondering if the engine would just break again. The guy i spoke to over there basically said I should trade it in and not go down the road of repairing and crossing my fingers.

detrails01 01-07-2013 11:33 AM

Well it all depends on how much you like that car, ya know? if its any more than 2500 at the dealer, that could also be a down payment on a newer wrx. :o I had a car that actually would burn coils out in a year or less which was probably an ecm issue. If you have an air compressor it is really easy to check for a burnt valve. Just need to pick up a compression tester. (fairly cheap) Attach the hose to the suspected cylinder and with the piston at tdc, let a little air in from the compressor. if its a burnt/bent intake valve, you will hear air coming out your intake. If its a burnt/bent exhaust valve, you will hear air coming out the back of the exhaust.


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