1998 Blazer revs at Idle

steve_blazer · 03-28-2005, 11:27 AM

Blazer is randomly reving at stop signs while in drive and also while in park. Ideas?

Scott01 · 03-28-2005, 12:59 PM

Dirty injectors
Weak pump
Clogged filter

Blazerboy · 03-29-2005, 03:09 PM

Messed with the throttle body or anything lately?

steve_blazer · 03-31-2005, 04:35 PM

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.

Blazerboy · 04-01-2005, 10:28 AM

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.

steve_blazer · 04-01-2005, 10:36 AM

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?

Blazerboy · 04-06-2005, 09:05 AM

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.

steve_blazer · 04-14-2005, 12:07 PM

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.

Skinny · 04-15-2005, 02:58 PM

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.

Vsandme · 04-29-2005, 09:28 PM

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

coolal · 07-08-2005, 01:45 AM

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

Vsandme · 07-13-2005, 11:12 AM

Blazerboy, 98 blazer isnt tbi, csfi

Scott01 · 07-13-2005, 11:34 AM

Quote: Originally Posted by Vsandme

Blazerboy, 98 blazer isnt tbi, csfi

But they have a throttle body on them.

skinnyg · 07-13-2005, 03:53 PM

I CANT BELEIVE nobody mentioned egr valve

03-28-2005, 11:27 AM	#1
steve_blazer Registered User Join Date: Oct 2003 Posts: 7 Location: User is: OffLine	1998 Blazer revs at Idle Blazer is randomly reving at stop signs while in drive and also while in park. Ideas?
	[Reply w/Quote]

03-28-2005, 12:59 PM	#2
Scott01 ZR2 member Age: 37 Join Date: Mar 2002 Posts: 1,903 Location: Northeast Ky User is: OffLine	Re: 1998 Blazer revs at Idle Dirty injectors Weak pump Clogged filter
	[Reply w/Quote]

03-29-2005, 03:09 PM	#3
Blazerboy Registered User Age: 37 Join Date: Feb 2003 Posts: 81 Location: User is: OffLine	Re: 1998 Blazer revs at Idle Messed with the throttle body or anything lately?
	[Reply w/Quote]

03-31-2005, 04:35 PM	#4
steve_blazer Registered User Join Date: Oct 2003 Posts: 7 Location: User is: OffLine	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.
	[Reply w/Quote]

04-01-2005, 10:28 AM	#5
Blazerboy Registered User Age: 37 Join Date: Feb 2003 Posts: 81 Location: User is: OffLine	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.
	[Reply w/Quote]

04-01-2005, 10:36 AM	#6
steve_blazer Registered User Join Date: Oct 2003 Posts: 7 Location: User is: OffLine	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?
	[Reply w/Quote]

04-06-2005, 09:05 AM	#7
Blazerboy Registered User Age: 37 Join Date: Feb 2003 Posts: 81 Location: User is: OffLine	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.
	[Reply w/Quote]

04-14-2005, 12:07 PM	#8
steve_blazer Registered User Join Date: Oct 2003 Posts: 7 Location: User is: OffLine	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.
	[Reply w/Quote]

04-15-2005, 02:58 PM	#9
Skinny Registered User Join Date: Nov 2002 Posts: 193 Location: Houston, TX User is: OffLine	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.
	[Reply w/Quote]

04-29-2005, 09:28 PM	#10
Vsandme Registered User Age: 23 Join Date: Feb 2004 Posts: 316 Location: User is: OffLine	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
	[Reply w/Quote]

07-08-2005, 01:45 AM	#11
coolal Registered User Age: 29 Join Date: Jun 2004 Posts: 11 Location: Central Florida User is: OffLine	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
	[Reply w/Quote]

07-13-2005, 11:12 AM	#12
Vsandme Registered User Age: 23 Join Date: Feb 2004 Posts: 316 Location: User is: OffLine	Re: 1998 Blazer revs at Idle Blazerboy, 98 blazer isnt tbi, csfi
	[Reply w/Quote]

07-13-2005, 11:34 AM	#13
Scott01 ZR2 member Age: 37 Join Date: Mar 2002 Posts: 1,903 Location: Northeast Ky User is: OffLine	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.
	[Reply w/Quote]

07-13-2005, 03:53 PM	#14
skinnyg Registered User Age: 30 Join Date: Jun 2005 Posts: 3,030 Location: MD User is: OffLine	Re: 1998 Blazer revs at Idle I CANT BELEIVE nobody mentioned egr valve
	[Reply w/Quote]