2000 Subaru Legacy Engine misfire

Tiny
MJAEGER
  • MEMBER
  • 2000 SUBARU LEGACY
  • 4 CYL
  • AWD
  • MANUAL
  • 150,000 MILES
2000 Subaru Legacy Wagon GT with approx 150,000 miles (5 speed manual). The wife�s car has an intermittent (though becoming much more frequent) high speed miss. The car will start and run fine. When under load such as entering the freeway it sometimes goes flat between 4500 & 5500 rpm and the �check engine light� flashes. Once at cruising speed (75 mph) the stumble will slowly subside, the �check engine light will stop flash (though not go out), and the engine will run fine. This has been happening for the last three months. It will throw four codes; one each for a misfire in cylinder #2, #3, and #4. The fourth code is for the knock sensor. Plugs, wires, and the coil have been replaced (twice). The knock sensor has been replaced and timing checked. Each time the car will run fine for a day, maybe two, then its back to misfiring and the engine light is back on. Thanks in advance. Michael
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Thursday, March 25th, 2010 AT 10:10 AM

7 Replies

Tiny
DOCFIXIT
  • EXPERT
Hi
Please post present codes in P0xxx format also check fuel pressure 30-34 psi
Let me know
Thanks for donate
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Thursday, March 25th, 2010 AT 1:04 PM
Tiny
MJAEGER
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I'll need to get those codes from my machanic. I'll likely see him Saturday. Thx for the quick response.
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Thursday, March 25th, 2010 AT 2:06 PM
Tiny
DOCFIXIT
  • EXPERT
I asked because P0302, P0303, P0304 misfire code will set the knock sensor code. So want to see what reset. Ask to have history of missfires ie. Number of times each cylinder has missed.
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Thursday, March 25th, 2010 AT 2:17 PM
Tiny
MJAEGER
  • MEMBER
10-04. I'll ask for the number of times each code is thrown. He has been reseting these codes but as I mentioned, they're back in a couple of days.
For a few weeks the car was fine dispite the -check engine- light being on. What is the distingtion between the engine light flashing (only during the misfiring) vs just on (when run OK)?
Thx Michael
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Thursday, March 25th, 2010 AT 2:26 PM
Tiny
DOCFIXIT
  • EXPERT
MIL will flash when multiple codes are being set when that stops then light goes steady
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Thursday, March 25th, 2010 AT 2:41 PM
Tiny
MJAEGER
  • MEMBER
I dropped the car off on Monday. The work done last week seems to have cleared the knock sensor code. The misfire is back and two codes were thrown. P0302 (cylinder 2) and one we haven't gotten before P0420 (Catalyst efficiency below threshold - bank 1). At least we're not getting the misfire codes on #3 & #4 as before. Our guy mentioned that the "O" ring on #2 was allowing oil to get into (and on top of) the #2 plug. Yesterday (Monday) he replaced the valve cover gaskests and "O" rings, reset the codes, hammered it down the freeway, and said we're in business. Any suggestions? I'll give it a couple of days and let you know how it's running.
Thx Michael
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Tuesday, March 30th, 2010 AT 3:22 PM
Tiny
DOCFIXIT
  • EXPERT
Seems your Tech is on top of it all that makes sence so you should be good to go.
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Wednesday, March 31st, 2010 AT 8:21 AM

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