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Old 07-17-2009, 04:38 PM   #1
tamadrumr88
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Default No engine codes, then bam! 4 codes

'97 Subaru Legacy 2.5GT Automatic w/ 121,600 miles - recent air filter, oil filter/oil change, seafoam treatment ONLY into intake manifold (not in oil/crankcase). All of these codes came on 2 days after doing this

P0102 - MAF (low input?)
P0303 - Misfire Cyl #3
P0304 - Misfire Cyl #4
P0597 - IAC (idle rpm higher than expected)

Is it possible that all of these could be caused by a single problem? The IAC problem looks like it could be a vacuum leak at the IAC (I have since removed, inspected, and retightened all clamps leading to/from the IAC and the idle dropped from ~900 down to ~700)

I have new plugs ready to go in, just have to check the gap and find time to install them. The weird thing is that the car doesn't noticeably misfire and it feels like it has decent power.

P0102, from my searching seems to be a common problem. I used MAF cleaner but I haven't been able to reset the codes.

Any other advice? I'm hoping they're all the result of one minor problem
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Old 07-18-2009, 08:41 AM   #2
Burnout
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All of those were probably from the vacuum leak. It sounds like you found the leak though. Clear it and drive it and see if any come back on.

Pete
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Old 07-19-2009, 12:45 AM   #3
tamadrumr88
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Went over everything again, cleared the code and it still came on
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Old 07-19-2009, 02:51 AM   #4
bcware
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All codes came back? Think MAF. If the MAF is fubar it could cause all of those codes. Messed up MAF values could cause bad air/fuel mixtures resulting in poor performance or misfiring if it got bad enough.

If you already have new plugs try them first.

Did you remove the intake manifold to clean it? I'm not familiar with the process of using sea foam, I've only heard of it.

Last edited by bcware; 07-19-2009 at 02:58 AM.
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Old 07-19-2009, 09:42 AM   #5
tamadrumr88
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http://forums.nasioc.com/forums/show....php?t=1755535

We had a scanner hooked up to it looking at real time figures and I think they said bank 1 was running just a tad lean (not enough to throw a code though). Not sure if that's also the result of the same problem. Doesn't blow any smoke black, blue, white... nothing
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Old 07-19-2009, 02:31 PM   #6
bcware
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You install those new plugs yet? If there is no smoke or smell then the fuel mixture is probably fine. I think misfiring could result in a loss of vacuum and throw the maf code. I'm thinking if the cylinder is already full of fuel/air from the previous cycle there would be no pressure difference on the intake stroke and thus 2 of the 4 cylinders lose vacuum resulting in low air intake.

I'd hate to jump to replacing the coil pack, but get on those plugs first I wanna see if that fixes the problem. Also, for giggles if you haven't already perhaps try disconnecting and reconnecting the spark plug cables while checking for contaminants.
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Old 07-19-2009, 11:07 PM   #7
tamadrumr88
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Thanks, I just don't understand how I go from having no CEL, to FOUR! I could understand if they came about after doing some work and possibly forgetting to plug something back in
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Old 07-20-2009, 03:01 PM   #8
bcware
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Don't get too hung up on that, it happens. More codes doesn't necessary mean multiple problems, just that you have a snag somewhere higher up in the chain of events. I'm optimistic that this is not going to be a complicated or expensive fix.
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Old 07-20-2009, 10:49 PM   #9
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My usual approach to finding leaks that might be lurking in hard to reach places is to spray starting fluid down around the base of the intake manifold and the injectors. Changes in the idle cues you to the location of the leak. It sounds like a leak, OR a bad IAC. A broken winding in the IAC would also cause these symptoms.
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Old 07-20-2009, 11:26 PM   #10
tamadrumr88
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I tried removing/cleaning the IAC yesterday, but had no luck. I removed the two 10mm bolts on the IAC, and the coolant hose running to the IAC, but it would not come loose. What was I missing? It seemed like it was pivoting on a bolt that I couldn't see
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Old 07-22-2009, 05:56 PM   #11
tamadrumr88
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Put in new plugs, gapped them to .044"

Been running for two days now CEL free
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