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Old 11-05-2006, 10:43 AM   #1
hikeeba
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Member#: 89165
Join Date: Jun 2005
Chapter/Region: MWSOC
Location: SE WI
Vehicle:
Poop Stuck Survivor
-=C=- & subari87 FOREVER!

Default P0304 #4 misfire = bad valve. Here's the valve.

Not too long ago, I had a flashing CEL problem. pulled codes P0301, P0302, P0303, and P0304. Dealership cleared all except the P0304 cyl 4 misfire. End result - a bad exhaust valve. Here is what caused the problems, and was thus responsible for a $3000.00+ repair: (notice the edge is flaked away)



It has been speculated that the valve was doomed from time of manufacture. The other valves in cyl 4 were ok, but replaced as a precaution.

And for those who missed it the first time, here's the original thread:
http://forums.nasioc.com/forums/show....php?t=1103830
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Old 11-05-2006, 11:50 PM   #2
Legba
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2005 STI
the best one

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yeah.... That's bad.
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Old 11-05-2006, 11:55 PM   #3
SubeTek
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Join Date: Jun 2000
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Location: Arvada,Co
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1999 RS-T COUPE
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i've seen this problem many times with higher mileage engines. What happens is that as the valves/seats wear, the valve adjustment becomes tighter and eventually the valve itself doen't make full contact with the seat. As this happens, the valve cannot conduct heat into the seat and basically gets hotter & hotter until it literally burns. I have on seen a few engines with lower mileage due this also due to improper valve adjustment. Generally it starts off as a misfire code now & then, then builds up to a code that won't go away and possibly a misfire that you can feel. I'm glad you problem got resolved & hope that no further issues arise. Happy Motoring!
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Old 11-06-2006, 10:53 AM   #4
hikeeba
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Member#: 89165
Join Date: Jun 2005
Chapter/Region: MWSOC
Location: SE WI
Vehicle:
Poop Stuck Survivor
-=C=- & subari87 FOREVER!

Default

Wow. Thanks for the info SubeTek. The tech at my dealership said he hasn't seen a valve burn up for a long, long, looong time. The tech, service advisor, and service manager couldn't recall when the last bad valve came through the dealership. They also said the 2.0 turbo motor was very solid, and they've seen very few problems. Same with the 02 manual transmission. So, were they feeding me BS?
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Old 11-07-2006, 09:54 AM   #5
SubeTek
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1999 RS-T COUPE
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The 2.0liter is a very strong engine & they weren't feeding you b.s.. I work @ the 3rd largest Subaru service department in the US so i tend to see more of the issues on these vehicles. As for the trans, just don't abuse it and it will be fine.
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Old 11-07-2006, 02:34 PM   #6
hikeeba
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Member#: 89165
Join Date: Jun 2005
Chapter/Region: MWSOC
Location: SE WI
Vehicle:
Poop Stuck Survivor
-=C=- & subari87 FOREVER!

Default

Whew! Thanks for the info SubeTek! I feel better now. I do not beat the car, and I do believe I am pretty careful with the transmission. Maintenace is either done by me or the dealership, so hopefully the car will last me at least another year, maybe 2 or 3 more years.
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