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grampadirt

"02 Trailblazer erratic idle and reduced engine power

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So,this is my son's Trailblazer....it went into reduced engine power one day on his way home from work and barely made it to my house.Plugged in my scanner and came up with P1512,P1515 & P1516.A friend of ours,after checking out You Tube installed a new throttle body,no change.It still has an erratic idle...goes up and down from 500rpm to about 2000rpm.Re-installed the old one and returned the new one.For some reason it got better and now only has a P1512 code.Did a idle relearn procedure but not sure if I did it right,no change.Both O2s acting funny so replaced them,no change.Tugged on the wires at the connector,no change.They seem fine.One odd thing though,the actual throttle position is at 22 and the throttle position desire changes as it should.Also when stepping on the gas pedal shouldn't the throttle blade move accordingly? It is fixed closed.

 

Any Ideas? I'm thinking of getting another throttle body.

 

Posted here because I saw nowhere else to post it.

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Well,got her running pretty good now,hopefully it will last.

 

Removed the #3 connector to the PCM and tested all the wires from the throttle body connector to check continuity....all were good.Noticed a split on a vacuum connector coming from the air box down to a fitting on the engine,replaced that.Went to AlldataDIY(been a member for years) and found that vacuum tube went to the fuel pressure regulator.Not sure if it had any bearing on the problem.I put it all back together and bingo!! The main dtc was p1512,correalation between the requested throttle body % and the actual %.So my son's pretty happy he has his car back :)

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Good to see you around Gary. Glad you figured out your issue.  :thumbs:

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13 hours ago, txab said:

Good to see you around Gary. Glad you figured out your issue.  :thumbs:

Thanks bud,i don't often post but i do browse the site occassionaly.

 

I bought an Autel MaxiPro808 scanner which helped a lot.

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