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Unread 08-22-2010, 04:40 PM   #5
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Name: scooter
Title: Administrator
Status: Offline
Join Date: May 2005
Location: US of A
Rate My Car: 296 / 340
Your Ride: 99m3
Originally Posted by Clarksonvalley View Post
Compression check as follows:

Left bank, front to rear = 200, 200, 202, 222

Right bank, front to rear = 200, 210, 204, 212

Engine was up to temp when I did the compression check, throttle was wide open, cycled each cylinder thru 12 compression cycles.

I did a leakdown test on the 222 psi cylinder - with 98 psi reference pressure, leakdown pressure was 97.5 psi.

I think it is an electrical problem - the plug is not firing. Any suggestions on how to check this out?

the plugs have nothing to do with the compression and as far as electrical issues i fail to see how that can be the case, your engine is wearing and its not wearing evenly as the numbers tell. the leakdown number is good but its only on one cylinder so you cant make too much of it, the 10% difference in compression isnt ideal.
the plug not firing can be an ecu issue or just a bad coil, swap it for another coil and see if the problem stays on the same cylinder or follows the coil.
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