I recently gutted and replaced my cat. (1999, 5.2) and now the truck runs terrible. Perfect at full throttle, but stumbles and pops at low end. You guys told me to clean the o2's, and I did with QD cleaner. Now the truck still has the problem, but get this. I pulled the rear sensor back out and it was so mangled it wouldn't even come straight out the bung. I guess there was a piece of the catalyst still in the system that just kept hitting it.

My question is: Will the rear sensor cause the truck to run poorly or does it simply throw the cel on?

 

The PCM uses the O2 sensors (in closed loop mode) to regulate the air/fuel mixture. At WOT ... you're running in open loop mode so the O2 sensor data is ignored. So ... to answer your question ... yes ... a messed up O2 sensor can make your truck run like garbage.

 

Thanks, I think you told me that in an older post. I've read though that the rear sensor will only throw the light on and not affect the way it runs. Any truth to this?

 

Read this and you decide: http://groups.google.com/group/rec.a...e207bfdfbe8919