I tested the voltage on my o2 sensors - defiantly running rich. I"m going to swap out both sensors and the cat. BTW - I cleaned out the EGR modulator filter and I think I can notice a difference in the throttle response. It was a freebie fix maybe some of you guys should try it. The how to is easy - pull the vacuum lines and pop the top cover off. Blow it out with compressed air.

This guy (Francisco@performancepeddler.com) got me a Magnaflow bolt on cat for $71.79 shipped. Thats about $20-$40 less before shipping than most other companies.

I have yet to hear of complaints on Bosch o2 sensors - IF they are the OEM replacements. I've heard plenty of issues with all brands of those universal sensors.

Rock Auto had an OEM replacement for the California emissions (upstream) for under $90 shipped. AutoZone wanted $200 for the same part number. We'll see how they work.

 

As O2 sensor wear, they get less responsive. This causes rich-lean-rich... cycling to slow down. They also report a leaner mixture than you actually have, so the computer makes the mixture richer to compensate. When this reaches a certain point, fuel trim exceeds a preset limit, sets a code and turns on the CEL.

 

Hmm, I keep reading about people saying to get the original Denso sensor in this application. I have no experience with it though.