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Old 04-13-2011, 07:03 PM   #1
THansenite
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Default Flashing CEL but no codes

This weekend, I purchased a "well worn" 2004 WRX. It has a cylinder with slightly low compression (100-125psi), but was getting a flashing CEL and misfire codes. Today, I received my new O2 sensor and I put that in the car. The car seems to run better, but I am still getting the flashing CEL at anything above idle. I used my AccessPORT v1 to check the codes and it says no codes stored on the ECU, even while the CEL is flashing.

I was told the plugs were just replaced, but I'm planning on getting new ones anyway just so I can rule that out. Any ideas what else could be causing the flashing CEL with no codes?
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Old 04-13-2011, 07:26 PM   #2
Badler
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Does it flash about 10 times in a row then go away? If so that is a misfire with more than a 10% variance. No bueno.
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Old 04-13-2011, 07:38 PM   #3
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ya need a rebuild...that low cylinder is gunna keep gettin lower
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Old 04-13-2011, 10:34 PM   #4
THansenite
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It flashes continuously.

I know I need a rebuild, but I want to get the car's misfire problem figured out first. With the compression still over 100, it isn't an immediate concern, but know that I want to get it fixed eventually.

This evening, I finally was able to pull P0300 and P0304 codes indicating random misfires as well as misfire in cylinder 4. Any suggestions on how to fix the misfire problem?
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Old 04-13-2011, 10:58 PM   #5
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jumped timing????
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Old 04-13-2011, 11:44 PM   #6
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Quote:
Originally Posted by Uncle Scotty View Post
jumped timing????
Just did a timing belt the day I bought the car and we quadruple checked that the timing was correct.
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Old 04-14-2011, 01:37 AM   #7
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and still have a constant flashing CEL and no other codes than the misfire codes......mmmmmmmmm

does the car have a light flywheel?


and low compression WILL cause a misfire
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Old 04-14-2011, 08:52 AM   #8
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Quote:
Originally Posted by Uncle Scotty View Post
and low compression WILL cause a misfire
^This. The ECU detects misfire by carefully monitoring the engine speed between combustion events. Your engine doesn't actually spin at a constant speed, it is always going up and down in speed. If one of the cylinders causes the engine speed to NOT go as high as it should, it will count a misfire.
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Old 04-14-2011, 09:17 AM   #9
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Ok, I didn't realize low compression would cause a misfire to be shown. It makes sense now that you say it. It just really scared me to see the flashing CEL while driving the car. Of course, the engine shakes a bit at idle, but I'm glad to know that it is most likely just the low compression causing the CEL.

Just to make sure though, that will cause the ECU to store codes for other cylinders besides the one with low compression? It still has the flashing CEL with only misfire codes. It usually has P0300 indicating random misfires, but also has specific cylinder misfires stored occasionally too.
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Old 04-17-2011, 10:29 PM   #10
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constantly flashing Check Engine light, first thing we check is the D-check connector under the dash. A green connector under the driver's dash, needs to be disconnected for normal operation. When it gets connected, the car goes into a sort of self-check mode and the MIL flashes constantly.
Are the cooling fans and other relays coming on and off repeatedly as well?
~Erik~
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Old 04-18-2011, 01:07 AM   #11
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Quote:
Originally Posted by zstalker View Post
constantly flashing Check Engine light, first thing we check is the D-check connector under the dash. A green connector under the driver's dash, needs to be disconnected for normal operation. When it gets connected, the car goes into a sort of self-check mode and the MIL flashes constantly.
Are the cooling fans and other relays coming on and off repeatedly as well?
~Erik~
you didnt read the thread did ya???
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Old 09-01-2018, 04:42 AM   #12
Chrispetit
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Default My 07 impreza outback sport is doing that

Quote:
Originally Posted by zstalker View Post
constantly flashing Check Engine light, first thing we check is the D-check connector under the dash. A green connector under the driver's dash, needs to be disconnected for normal operation. When it gets connected, the car goes into a sort of self-check mode and the MIL flashes constantly.
Are the cooling fans and other relays coming on and off repeatedly as well?
~Erik~
Where exactly is this connector at under the dash so I can check it
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Old 09-01-2018, 06:17 AM   #13
Blktrax
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Directly above the Brake and Clutch pedals (have to lay on your back and look up sometimes) Bright green connectors , single wire
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