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Old 03-01-2021, 01:01 AM   #1
mitchfishman5
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Default Lean caused from Leaky Valve Cover Gaskets?

So I took my car into the shop last week to have them run a smoke test and they ended up finding one bad leak and replacing the hose. Got it back from them and everything looked good, no more lean, fuel trims looked fine until about 30 minutes later. I got a P0171, was running lean and my trims were back in the 20% range. I took it back and watched them smoke it, then found 2 leaks, one little one in one of my hoses and then a pretty good amount of smoke coming from my leaky valve cover gasket. They told me that my best bet was to pay the $400 and get those replaced and that it would most likely solve my problem. To me this sounds unnecessary as the car ran fine for a while prior to taking it back into the shop but that being said I also didnít see any smoke coming out from anywhere else. From what I have read on the fourm there is a lot of conflicting information. Any ideas on what to do?
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Old 03-01-2021, 03:02 AM   #2
murrdogg24
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you would see oil leaking out from the valve cover gaskets but I don't think it would cause the car to run lean...in any case you should probably get the gaskets fixed.
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Old 03-01-2021, 09:59 AM   #3
subaru_gc8
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why do you think its a leak? most lean codes are maf related problems. inorder to have the PO171 come up its gotta be a really bad leak.
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Old 03-01-2021, 11:57 AM   #4
rtv900
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a valve cover would have less than nothing to do with a lean condition
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Old 03-01-2021, 12:08 PM   #5
mitchfishman5
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Ok that's what I thought. I watched the shop smoke it and didn't see any significant leaks but I had the same exact symptoms when I did have a leak. The weirdest part was that it was running fine for a while until the AFR and fuel trims got all screwed up.
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Old 03-04-2021, 02:46 AM   #6
EconMitch
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Sounds to me like you need a tune if you're running lean.

P.S. fix that smoke first
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Old 03-07-2021, 01:04 AM   #7
TwistedAxles101
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Oil could be dripping on to the a/f sensor clogging up the little vent holes. I've seen this cause a lean reading before 100%. Not saying this is your issue, but you should go see if it's oil covered.
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