Thread: 04 Grand Prix Stuttering on acceleration

I am still having issues with my GP, and have bought a bluetooth scan tool to work with the Torque app on my android. I am not sure what I should be looking for to help diagnose this issue. Upstream O2 sensor is switching back and forth as it should, downstream stays pretty steady most of the time at about .75 volts though it does switch during acceleration. If the car bogs on acceleration they both drop to 0 to .1 volts. I checked Knock Retard and from what I have searched it seems excessively high especially when the car bogs and have seen up to 12 degrees of KR, though on non-bog acceleration it hits about 6 degrees.

If none of that is helpful, I can look at other things but need a direction.

Thank you for your assistance!

Fixed! It got real bad, dying on the freeway after dropping to 500 rpm's under acceleration. Not starting for 5 mins in heavy traffic was quite the experience from the center lane...

Called a friend I knew worked as a mechanic and he told me to turn the key to on, unplug the EGR and then start it and see if it has issues. My EGR is the issue - drive it for a week unplugged then plug it back in and if it's bad replace it.

It accelerates like brand new on acceleration now.

Thanks all for the help!

Also got a nice tool to check if the cat was plugged today before calling him, an O2 Sensor socket. If this link works from O'reilly's http://www.oreillyauto.com/site/c/de...2546&ppt=C0195. CAT is fine and changed nothing about how it was running when the upstream sensor was taken out.