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Old 11-11-2012, 07:04 PM   #1
bubbajan21
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Exclamation HELP: 99 Forester rough idle with flashing CEL

Hello all,
I just bought a 1999 Forester today and right after I picked it up the CEL started flashing. I immediately pulled into a gas station and shut off the car and called the seller. The car had a rough idle from the second I picked it up. He said, as he had disclaimed in the listing, that it probably needed plugs and wires. I stopped at Autozone and pulled codes, it was cyl. 2 misfire. I wiggled the wires and the light went from flashing to solid so I figured I would drive it home. I drove the car an hour home, the light was solid not flashing, cruise control worked great, and promptly changed out all 4 plugs (NGK Platinum) and wires. The plugs were in fact fowled (badly). I cleared the codes, the car drove much smoother, and I drove the car back to my apartment about 1.5 hours away purely highway miles. The entire way there, the car drove great, no issues, noises, vibrations, hesitations, or CEL. As soon as I came to a stop on the offramp and the car started idling, it was still rough and the CEL started flashing again. I turned and started driving again and the flashing light shut off and the car was happy again. The next stop I came to, idle was rough again and the light started flashing again. This was a longer light and when I pulled away it stopped flashing but just stayed on solid. Anyone have any ideas what would cause a forester to drive perfectly fine but have a rough idle accompanied by a flashing CEL?

Thanks in advance,
Alan
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Last edited by bubbajan21; 11-11-2012 at 07:18 PM.
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Old 11-11-2012, 08:38 PM   #2
RallyB
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could be the intake manifold, might be clogged with dirt
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Old 11-13-2012, 07:34 PM   #3
subaru-tech
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Check the coil for any arcing.Possible coil problem???
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Old 11-13-2012, 08:09 PM   #4
cal_look_zero
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344hp/348tq

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Flashing is indicative of a currently occurring misfire. You could have anything from a dirty air filter, to a bad injector, to a bad coil, or even a clogged fuel filter. Worst case scenario, burned valve(s).

Go get a compression test done to rule out the latter before the seller skips town. Then replace the air and fuel filters (even if that doesn't fix it, they're still maintenance items), then start testing out the other items.
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Old 11-13-2012, 08:33 PM   #5
bubbajan21
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Quote:
Originally Posted by subaru-tech View Post
Check the coil for any arcing.Possible coil problem???
I had suspected the coil since it's the only thing left to replace in the ignition system, but I was told that if it was a coil problem I would have a problem on more than just one cylinder. I may revisit that if nothing else fixes it.


Quote:
Originally Posted by cal_look_zero View Post
Flashing is indicative of a currently occurring misfire. You could have anything from a dirty air filter, to a bad injector, to a bad coil, or even a clogged fuel filter. Worst case scenario, burned valve(s).

Go get a compression test done to rule out the latter before the seller skips town. Then replace the air and fuel filters (even if that doesn't fix it, they're still maintenance items), then start testing out the other items.
I'm just very confused as it seems to me that all of those things would get worse with higher RPM's and therefore higher need for fuel / air. The air filter is new, so the suspects are maybe a bad injector, bad coil (any idea if a coil would go out completely or if it's common to see one cylinder go out?), fuel filter, or maybe a bad valve?

Could it be a vacuum leak? I was talking to a friend who is a mechanic and he suggested that since (according to him) there's a separate vacuum circuit for idle vs. driving??

I'll do a comp. test this weekend.
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Old 11-14-2012, 08:38 AM   #6
bubbajan21
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Quick update, I had my first fuel fill-up and I got 23.3 MPG. Anyone have any input if that implies a healthy engine or otherwise or if that's about the norm for a healthy car?
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Old 11-14-2012, 08:10 PM   #7
medfordhotrodguy
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Did you happen to buy this car up at Tahoe?
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Old 11-20-2012, 12:24 PM   #8
srikid
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I'm having very similiar issues. Please post solution if you find one. Thanks!
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