Engine revving up amp down

Tiny
SETHE312
  • CHEVROLET BLAZER

1995 Blazer 6 cylinder 2wd 190000. My enging is revving up and down very badly. You can hear it sucking in air as it revs back up. I have changed the plugs, wires, distributer cap & roter, fuel filter, air filter, egr sensor and throttle position sensor. I checked the o2 sensor near the exhaust line and it was clean. A friend of mine metioned that there may be another o2 sensor near the back of the moter. Is this correct and how easy is it to do for a shade tree mechanic like my self? If that's not the problem, does anyone have any ideas? Thanks

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Friday, September 14th, 2007 AT 6:14 PM

4 Replies

Tiny
CLY
  • MEMBER

I would not worry to much about that secondary o2 sensor right now. I would be more concerned in trying to find a vacumm leak. May have something going on the Idle air control motor. Is it setting any trouble codes?

Cly

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Saturday, September 15th, 2007 AT 5:52 AM
Tiny
SETHE312
  • MEMBER

It hasn't caused the check engine light to come on, at least not more than for a few minutes. I am getting TERRIBLE gas mileage (less than 200 miles to the tank). I have a noticeable decrease in power. Where and how would I check for an vacuum leak? When in idle or stoped in dive, the RPM's will drop suddnly, the voltage will dropand then you will hear the motor sucking in air as it throttles back up. Thank you for the quick reply and info.

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Saturday, September 15th, 2007 AT 7:08 PM
Tiny
STCCWRESTLER157
  • MEMBER

Im actually having a similiar problem with my 1992 chevy s10 blazer with 146000 on it but my rpms arent going up and down my oil pressure is and I had my vacum hoese replaced and its still causing a problem

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Sunday, September 16th, 2007 AT 12:10 PM
Tiny
HOTROD56
  • MEMBER

I have always had good luck spraying carb cleaner around the intake and watching for white smoke out of xhaust, 9 times out of ten , intake leak mening huge vacum leak.

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Thursday, October 25th, 2007 AT 7:23 PM

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