2002 Subaru Impreza engine misfire

Tiny
JDWRX
  • MEMBER
  • 2002 SUBARU IMPREZA
  • 4 CYL
  • AWD
  • MANUAL
  • 140,000 MILES
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
Sunday, March 16th, 2008 AT 6:53 PM

9 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
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.
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Sunday, March 16th, 2008 AT 7:05 PM
Tiny
JDWRX
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Ok thanks. Since im kind of newbie to cars, what will a compression test determine?
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Sunday, March 16th, 2008 AT 7:09 PM
Tiny
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
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Sunday, March 16th, 2008 AT 11:08 PM
Tiny
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
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Monday, March 17th, 2008 AT 7:16 PM
Tiny
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?
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Sunday, March 23rd, 2008 AT 10:05 PM
Tiny
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If times permit comeback with the 2 readings that way we can determine the engine's power output/balance-
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Monday, March 24th, 2008 AT 12:37 AM
Tiny
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.
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Monday, March 24th, 2008 AT 9:39 PM
Tiny
JDWRX
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  • 12 POSTS
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?
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Monday, March 24th, 2008 AT 9:43 PM
Tiny
RASMATAZ
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My opinion I'll go for a used engine
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Tuesday, March 25th, 2008 AT 6:03 AM

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