Quick question..Does the O2 Sensor regulate the idle speed and throttle control? or is there a seperate sensor for that? I know it measures the fuel/air ratio to the manifold..(I'm pretty sure anyways) Just wondering! Thanks!

 

The idle speed is controlled by the Idle Air Control (IAC) valve. I am not sure what you mean by throttle control, but the cruise control is controlled by the cruise control module (follow the throttle cables - the one that doesn't go into the firewall is the cruise cable).

The O2 sensors monitor how much free oxygen is still in the exhaust which is a measure of how complete the combustion process was and the PCM corrects the air/fuel ratio accordingly to maintain complete combustion.

 

Ok..so the question is what sensor would be off to make my truck surge rpms..and make it move forward? I figure it has to be a sensor some where..it's not the accelerator sticking..it seems to happen when the compressor kicks on...any ideas?

 

Could be your Throttle Position Sensor...

I know the computer bumps the idle up a few RPM when the compressor is on... So maybe your IAC is moving a little more than it should...

 

I would remove the throttle body and clean it very well. I bet the IAC is sticking up a bit, causing it to over adjust when the PCM tells it to. The easiest way to clean the IAC is to remove the TB, but have a look at it, you may be able to do it with it still on the motor. The cruise cable can be a PITA to remove.

 

cool! thanks guys...I was looking in a book and narrowed it down to that or the EGR...deffinately add it to the list of things to do to my blazer this spring...hopefully get my gas milage back up!