Mechanics

ENGINE REVVING UP & DOWN

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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Sethe312
September 14, 2007.




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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Tiny
Cly
Sep 15, 2007.
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.

Tiny
Sethe312
Sep 15, 2007.
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

Tiny
Stccwrestler157
Sep 16, 2007.
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.

Tiny
Hotrod56
Oct 25, 2007.

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