Of course it's the upstream sensor, it is switching slow which I believe despite having a brand new sensor, it does not thread down far enough to completely be in the exhaust stream. The customer sent me a picture, it looks like an early zzp longtube header, the bung is sticking out I believe to be way too far I know GM sensors are very shallow threads.

Has anyone else had problems with various brands of long tube headers having O2 sensor performance problems? My intention is to simply grind the bung down until the sensor is completely in the stream and call it good. It looks to me like the maker of the header used the deep weld on bung from summit racing.

The customer sent me a pic of the header and bung on facebook. I'll reload it to my website so you guys can see it.

For those of you having dealt with it before, do you think grinding the bung down will resolve this or do I need to weld in a new bung elsewhere and if so...best place?

 

Ohh and it's a midlength header, not a long tube...zzp is the brand I think.

 

try posting this in the my car is broke section its called problems and service

 

Ok, someone can move it for me if they see it, but this is specific to this engine is it not?

 

this is specific to how to make more hp/tq hence the name performance section