2002 Subaru Impreza engine misfire

2002 SUBARU IMPREZA
140,000 MILES • 4 CYL • AWD • MANUAL
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JDWRX
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After driving the car hard, the check engine light started flashing, so i got home and scanned the code. I got a misfire in cylinders 2 and 3. I have replaced the spark plugs with oem ones, i have also switched the coils from a good cylinder with a bad cylinder, and i have checked the fuel injectors, which i also interchanged, but i continue to have misfires in those cylinders. I'm not sure what to check for next, so i am asking for some advice. THANKS
Mar 16, 2008 at 6:53 PM
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RASMATAZ
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Check the compression for 3/2 cylinder

Misfires can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.
Mar 16, 2008 at 7:05 PM
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JDWRX
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[quote:de99bfee2d="rasmataz"]Check the compression for 3/2 cylinder[/quote:de99bfee2d]
Ok thanks. since im kind of newbie to cars, what will a compression test determine?
Mar 16, 2008 at 7:09 PM
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RASMATAZ
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It will determine if that cylinder is leaking compression valves/rings not producing its share of power output the CPS wil sense it and reports this as misfire to the computer.

Recheck the coils -cyl 1 and 2 shares the same coil
Mar 16, 2008 at 11:08 PM
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JDWRX
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i ordered a compression tester, which will be arriving the next couple of days. i will probably do the compression test this weekend because of work, but i will get back to you with the results as soon as i can. thanks
Mar 17, 2008 at 7:16 PM
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JDWRX
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i did the compression test on cylinder 2 and i got 150psi and the same for cylinder 4. i only had time to do those two, but i think they look ok,right?
Mar 23, 2008 at 10:05 PM
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RASMATAZ
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If times permit comeback with the 2 readings that way we can determine the engine's power output/balance-
Mar 24, 2008 at 12:37 AM
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JDWRX
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well i just finished doing the compression test on cylinders 1 and 3 and i got some bad results. cylinder 3 has no compression at all.
Mar 24, 2008 at 9:39 PM
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JDWRX
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in your expert opinion, how much would the repairs be if it was the valves? or rings? or would i be better off finding a used engine?
Mar 24, 2008 at 9:43 PM
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RASMATAZ
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My opinion I'll go for a used engine
Mar 25, 2008 at 6:03 AM