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Old 10-06-2010, 10:30 PM   #1
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Default HELP. misfire? running rough

i have a 1990. with a sr t25. stock everything else.
ive had the set up on for about 3 months. stock ecu. havent got on my car past half throttle. retarded ignition timing some.

today, at lunch, it randomly started idling like it was a misfire. it still has the power its had. and not lag.
when i drive it, still has the rough sound, it sounds like an exhaust leak. so i replaced the the manifold gasket, and turbo gasket.
i smell a slight hint of oil. but its not constant.
i changed plug, wires, and ran a compression check (1-175psi. 2-140psi. 3-172psi. 4-170psi.)

im irritated with it....need some help.
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Old 10-06-2010, 11:03 PM   #2
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...and its not throwing any codes.
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Old 10-07-2010, 12:15 AM   #3
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How much boost were you running? Intercooled or not? That number 2 compression reading is screwed up. They shouldn't vary that much.

Did you pop the head gasket or crack a piston maybe?

Need a little more info on the setup.
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Old 10-07-2010, 12:24 AM   #4
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im running 7psi. non intercooled. basically slapped it on. ive been babying it the setup was put on.

im not sure if the headgasket is blown, no water in oil.
with out taking the head off, how do i check the piston. besides a scope.
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Old 10-07-2010, 12:32 AM   #5
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A leak down test might be able to pinpoint the cause of compression loss. To be honest, I'm not sure, I've never had to do one. Something is definitely amiss in your number 2 though.

You may have popped the headgasket and that could be the noise you're hearing.

I'm sure someone more knowledgeable in the leak down procedure will chime in or you can Google it.
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Old 10-07-2010, 12:36 AM   #6
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What did the spark plug look like when you pulled it? Was it wet? Was the inside of the cylinder wet?
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Old 10-07-2010, 12:43 AM   #7
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the spark plugs and cylinders were dry. the plugs had the look of being ran hot, and rich.

i'll research the leak down procedure.
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Old 10-07-2010, 12:46 AM   #8
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Let me get this straight you are running the stock ecu, stock injectors with no fuel supplementation and no intercooler at 7 psi?

I don't know if that's such a good idea. You might have messed something up.

Were the plugs white? I bet your running lean not rich. In boost anyway.
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