Hello Everyone,

When I am at the stop sign the Blazer revs about every 20 seconds or so. I also notice that while driving the rev also is apparent. Can anyone tell me what might be the problem?

Thanks in advance
Bill

 

Probably a vacuum leak from a broken cracked or disconnected rubber vacuum hose.

Any time you have a question it's to your benefit to include your vehicle info. If you edit your profile to include your vehicle info it will show up on all your posts and we won't have to ask what year, make, model and options do you have.

 

*Moving to 2nd Gen Tech*

I would be inclined to clean the throttle body and EGR valve. It is possible that it is a combination of a dirty EGR valve and a dirty IAC (idle air control) valve (in the throttle body). The EGR valve is located on the front of the intake and is about the size of a soda can.

 

If you have AC on your truck..the AC compressor disk thing...when it kicks on..makes your engine rev a little...just something else to check...