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1998 Blazer revs at Idle

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Old 03-28-2005, 11:27 AM   #1
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1998 Blazer revs at Idle

Blazer is randomly reving at stop signs while in drive and also while in park. Ideas?
Old 03-28-2005, 12:59 PM   #2
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Re: 1998 Blazer revs at Idle

Dirty injectors
Weak pump
Clogged filter
Old 03-29-2005, 03:09 PM   #3
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Re: 1998 Blazer revs at Idle

Messed with the throttle body or anything lately?
Old 03-31-2005, 04:35 PM   #4
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Re: 1998 Blazer revs at Idle

No changes to throttle body. I have had suggestions that IAC may need cleaning. Also, had one person say that AC low on freon caused their blazer to rev every 5-10 seconds. Thanks for help.
Old 04-01-2005, 10:28 AM   #5
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Re: 1998 Blazer revs at Idle

If the A/C is off at the time, it shouldn't cause it to rev.
Is the idle just coming up when you stop or is it surging up and down, up and down? I agree if the IAC is dirty it could cause a surging idle.
Old 04-01-2005, 10:36 AM   #6
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Re: 1998 Blazer revs at Idle

Yes, it is as you describe. It surges up and down every 5 or 10 seconds while stopped. It hasn't been noticeable while driving. My son is driving the vehicle, so I won't see it until the weekend. The AC idea made some sense as it was very poor cooling last fall. Also, doesn't the AC get involved in some other air flow settings which might be in use now? I was planning on pulling the AC fuse first and then seeing about getting at the IAC. Would you suggest replacing the IAC or is a good cleaner a good choice?
Old 04-06-2005, 09:05 AM   #7
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Re: 1998 Blazer revs at Idle

The A/c compressor kicks on whenever you're in A/C or defrost. So yes defrost setting will engage the compressor and may drag the motor down. Pull the IAC valve and clean it out real good with a carb cleaner, and while you're at it clean out the bore in the throttle body where it sets and see if that helps any. Also check for any vacuum leaks as well.
Old 04-14-2005, 12:07 PM   #8
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Re: 1998 Blazer revs at Idle

Thanks for help and advice. The problem is the AC. Not sure yet what is wrong with AC, could be low coolant, I suppose. Determined it was the AC by pulling the 10 amp fuse for the AC. Problem immediately went away and didn't return again until fuse was plugged back in. The air setting was on defrost and that was causing the AC to try to engage.

Visually, it looks like the AC clutch is engaging every few seconds and then kicking out again. Little to no cool air is coming out. Any thoughts on the AC? Imagine I will need to have that serviced, but it would be good to know if you think it is coolant, if they suggest something more drastic with the AC.

Blazer is back at college again, so I won't see it for a while. Thanks again.
Old 04-15-2005, 02:58 PM   #9
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Re: 1998 Blazer revs at Idle

Probably just low on freon. You can get a do-it-yourself kit at Wal-Mart or any auto parts store to recharge your system yourself. Be sure to get freon with stop-leak in it. You should be able to get all this for about $20. The directions will be easy to follow. If this doesn't work, then you should take it to a mechanic to have it looked at, but not before trying to remedy it yourself.
Old 04-29-2005, 09:28 PM   #10
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Re: 1998 Blazer revs at Idle

Same problem here, ended up cleaning the mafs and it stoped, but mine did it when a/c was off so different case i guess
Old 07-08-2005, 01:45 AM   #11
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Re: 1998 Blazer revs at Idle

Quote: Originally Posted by Vsandme
Same problem here, ended up cleaning the mafs and it stoped, but mine did it when a/c was off so different case i guess
mine does the exact same thing with air off, Vsandme what is mafs where are they i have a 95 blazer and its driving me nuts
Old 07-13-2005, 11:12 AM   #12
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Re: 1998 Blazer revs at Idle

Blazerboy, 98 blazer isnt tbi, csfi
Old 07-13-2005, 11:34 AM   #13
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Re: 1998 Blazer revs at Idle

Quote: Originally Posted by Vsandme
Blazerboy, 98 blazer isnt tbi, csfi
But they have a throttle body on them.
Old 07-13-2005, 03:53 PM   #14
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Re: 1998 Blazer revs at Idle

I CANT BELEIVE nobody mentioned egr valve
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