Another rough running wrx

[late96]

Trying to help a buddy, 02 WRX rough idle, replaced plugs and they turn black immediately. compression varies from 95 to 140, did notice turbo intake ripped at clamp by turbo. Could this be issue? Anyway to test coils? They all create spark turning over with spark tester. Has 154,000 miles and not sure of history. Looking for some direction. Thanks

[SD_GR]

did notice turbo intake ripped at clamp by turbo. Could this be issue?

This is a issue. There is another.

compression varies from 95 to 140,

That's an issue. I believe the service limit is 122 or something like that; in any case, it's higher than 90. That's a problem.

Anyway to test coils?

You have low compression in a cyl. That sounds from here like a show stopper.

[late96]

Thanks, I will double check again tommorrow, doesn't look good according to your thoughts. Did'nt want to start throwing parts at it if it was done. thanks Brian

[Sinister]

engine may be toast with jacked up compression. when you say varies.. do you mean between cyls? was it tested cold or warm? leakdown performed?

[late96]

I checked it warm, I will recheck tonight. Should it bee warm and how long should I crank? I was counting about 5 compression strokes per cyl. The 2 plugs on passanger bank will turn carbon black in 2-5 minutes of running, these if I recall were the lowest on compression. Thanks Brian

[Donkey]

The 2 plugs on passanger bank will turn carbon black in 2-5 minutes of running, these if I recall were the lowest on compression. Thanks Brian

Sounds like goners. Just make sure you hold the throttle plate open when you are doing the compression check. You only need 1 compression stroke. A leak down test might be able to tell you if it is valves or rings.

[late96]

So warm or cold or does'nt matter? Thanks

[Donkey]

You want to do it warm. Google search "compression test".

[late96]

Ok, ran car for like 5 minutes, copression test oassanger side 105 and 110 drivers side 150 and 155. Any suggestions? Thanks Brian

[SD_GR]

Find out why two cyls have lower compression than the service limit whereas the other two are seem in great shape. At this point see what you're willing to do as far as digging. A leakdown isn't too much hassle and might tell you if it's top end or not.

[late96]

Just finished leakdown. Front passenger side 10% and rear passenger side 28%. Now what

[teflon_jones]

Sounds like your rings are toast on the passenger side. It could be the valves too, but my money's on the rings. Time to either rebuild the engine or buy a new one.