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02-01-2009, 01:54 PM | #1 | |
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Idle high, accelerates on it's own.
Having problems. My 98 4x4 Chevy Tahoe has very high idle. Usually around 1000 at start, and after warmup, around 1200. I performed a tuneup w/AC Delco's, new cap/rotor, wires. Changed the IAC valve, (even though I had no codes, and the fuel pump. I am getting a P0304 and a P0507. I hear the K&N hissing really loud vacuuming air into the filter. My Bank 2 fuel trims are around -8 to -17. Bank 1 is fine usually around 0-1. Also once I begin to decelerate, it takes a while while approaching a stoplight. Very hard to stop the truck. Any Ideas? Can this be an O2 sensor? I wish I can afford to take it in or get a live readout. Getting very upset.
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02-02-2009, 11:44 AM | #2 | ||
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Re: Idle high, accelerates on it's own.
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when cold the idle should be 1200rpm...then in a shot time drop to about 700rpm...neutral... the other possibility is the throttle body gasket.... |
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02-04-2009, 07:15 PM | #3 | |
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Re: Idle high, accelerates on it's own.
I read the MAF sensor and the wires and it checks good. I even replaced with a known good MAF. Same thing. Still misfire on #4 cylinder, idle does not go down to 700. In fact, it rises to 1200 once warm. Could this be a timing issue with the distributor, o2 sensor maybe? I'm stuck.
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02-05-2009, 01:24 PM | #4 | ||
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Re: Idle high, accelerates on it's own.
Quote:
you also could have an intake manifold leak or bad PCV/hoses etc...anything bypassing the MAF causing the engine to get too much air .. |
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02-07-2009, 10:40 AM | #5 | ||
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Re: Idle high, accelerates on it's own.
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Thanks. How do I check for leaks on the intake manifold? |
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02-07-2009, 07:24 PM | #6 | |
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Re: Idle high, accelerates on it's own.
I'm not a mechanic but i've had the same problem in my 96, i changed my intake gasket was good. If i were you id change it because if it goes bad it dumps water into the oil, causing all sorts of other issues.
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02-07-2009, 08:39 PM | #7 | |
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Re: Idle high, accelerates on it's own.
That sounds like the way to go alright. After doing some research on the same subject, I purchased a can of MAF sensor cleaner and sprayed all of my vacuum lines. I sprayed along the base of the intake and realized that the RPM would rise. I am in the process of tearing this baby up. Thanks a lot. Will let you know how things turn out.
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02-08-2009, 09:25 AM | #8 | ||
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Re: Idle high, accelerates on it's own.
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looks like your on to repairing this.. |
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02-08-2009, 01:04 PM | #9 | ||
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Re: Idle high, accelerates on it's own.
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02-08-2009, 03:29 PM | #10 | ||
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Re: Idle high, accelerates on it's own.
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pep boys has had a few forum members pissed off.. what I'm getting at is corroded metal usually causes failures of the coolant system....the coolant type and frequency of replacement is for my knowledge... |
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02-16-2009, 01:45 PM | #11 | ||
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Re: Idle high, accelerates on it's own.
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02-21-2009, 10:01 PM | #12 | |
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Re: Idle high, accelerates on it's own.
One easy quick repair is clean throtle body with old tooth brush and throtle body cleaner...comon for theis tb to get gunk build up and not run right
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