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Old 02-04-2004, 02:56 AM   #1
fellfrosch7
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'98 Impreza L Wagon
'90 Talon TSi AWD

Default Misfire problems

My car constantly keeps throwing the P0302 and P0304 misfire codes ('02 WRX engine). I can clear them, and they come back within several miles. I did notice that if I clear the codes after the car is warmed up, it takes a little bit longer for it to come back than just starting the car up cold and clearing it. The idle is also a bit rough - the car shakes a tiny bit more than it used to.

I changed the spark plugs, and it didn't help. The CEL usually comes on when I'm sitting at a stoplight. It's a solid light, no blinking or anything. The car seems to be running OK in the middle and upper RPM's.

Ideas? Bad coil packs maybe?
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Old 02-04-2004, 03:49 AM   #2
Uncle Scotty
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Do a proper compression test......
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Old 02-04-2004, 09:56 AM   #3
vile
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when was the last time you replace all the maintance items? plugs, plug wires, air cleaner, fuel filter, cap & rotor
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Old 02-04-2004, 01:47 PM   #4
cdvma
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Its a WRX engine...no plug wires or cap & rotor. The drivetrain was transplanted into the L chassis less than half a year ago but I dont know if he changed the air/fuel filter..I imagine he did.
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Old 02-04-2004, 01:53 PM   #5
Subie Gal
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diagnostics indicate you have cylinder misfires.

procedures indicate:
check for spark on spark plugs.

If you have spark on all 4 - pull the timing belt cover off.
are all of the markings lined up?
did the timing jump?
are there missing teeth?

if this is all 'okay'
you should do a compression test.
also check fuel injectors, wires, coil packs

hope this helps in some way
good luck to you.
Jamie
www.subiegal.com
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Old 02-05-2004, 02:00 PM   #6
fellfrosch7
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I ran some fuel injection cleaner through the car, and it didn't help. Like cdvma said, it's a WRX motor with about 20k miles on it now. It got a new air filter and fuel filter at the time of install.

Last night, I cruised on the highway for about 120 miles without a CEL. I pulled over to get gas, filled up, started the car, and within 50 feet, it threw the same codes.

I'm pretty sure it's getting spark on all cylinders. I'm going to try to switch the coil packs from one side to the other to see if those are bad. After that, I'll do a compression test and check the timing belt.
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Old 02-05-2004, 04:08 PM   #7
grindMARC
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Quote:
Originally posted by fellfrosch7
I'm going to try to switch the coil packs from one side to the other to see if those are bad. After that, I'll do a compression test and check the timing belt.
I had similar problems a few months ago. From everyone I spoke with, its VERY unlikely that its the coils. I put in new plugs, new fuel filter, cleaned the airbox really good (including that sensor in there) and did the coolant. Funny thing, I threw another misfire code later that day after doing all the work. I washed and waxed the car and the code went away. Hasn't come back since.

I guess its worth mentioning that I didn't do the proper code clearing procedure after I did all the work. IIRC, I just disconnected the battery for a few minutes. So, I'm not sure the wash and wax was really the answer!
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Old 04-26-2005, 05:03 PM   #8
Demian_w
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Here is my story. I am running a PnP VF34 with the STi injectors on the Cobb 2.5 tuning platform. I kept getting the P0302 code for Cylinder #2. Nov-Dec 2004, I changed the spark plugs 6 times (copper NGKs, one degree colder), frustrated, I finally switch out the coil packs. The problem moved with the coil pack. I replaced the coil pack for $112 and the problem went away.

Until this last week - 4 months after switching out the coil pack- I pulled another P0302 misfire code. This time, I did a compression test. Cylinder #2 is pushing about 87 psi compared to 138 to 140 psi for the other three cylinders. Uh oh. I ran a tank of gasoline mixed with 44F engine cleaner thru the engine just-n-case I had some build-up in cylinder #2. I don't know if my non-firing coil pack (from 4 months ago) somehow damaged my cylinder, but, this is the same P0302 code and it is on the same #2 cylinder. The same cylinder that had a non-firing coil pack.

Currently, I pull a solid P0302 now. I keep resetting the ECU. My WRX seems to run great. It sounds great while seemingly delivering great power.
I need to schedule a leak-down test to find out more. Is my cylinder good and maybe it is something else/different? Or, is it a sad state for an engine with 53,000 miles on her?
P.S. the Tranny is holding up great.
edit ~ Cylinder #2 piston is shot. Cracked the ring land. Detonation was the culprit. I have replaced my block and my poor old car is now stock again.

Last edited by Demian_w; 07-07-2005 at 05:38 PM.
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