I went with a friend of mine to get his car tuned this weekend. We both have S's and do lots of car stuff together.

Anyway, the tuner connected the sensor for the wideband into the O2 sensor bung on his test pipe. That is all fine and normal, however he had the Berk test pipe with the lengthened bung to pull the sensor out of the exhaust stream. I told the tuner that and suggested it may not read properly. He went ahead with it anyway.

The sensor did get a reading. My question is, would it be an accurate one? He was able to tune the car to a very nice looking A/F ratio. However, the car made ZERO additional power. At no point in the curve did it really make any improvement. Also, he was unable to lower the VTEC enagagement point at all. Even dropping it 500 rpm caused the car to studder badly at VTEC.

The car had AEMv2, Rick's header, Berk test pipe and Comptech Exhaust. Was tuning with VAFCv2.

Would the lengthened bung thrown off the wideband readings? Could he have placed the wideband in the first O2 sensor bung, the one in the header? He said that would have caused a CEL, but who cares, we could have cleared it when we were done tuning.

Thoughts?

Thanks,
J

 

Bump, someone has to know.

 

Last try, I know someone has some input.

 

I'd think the reading would be a lot leaner which in turn would make him your car way too rich, thus no added power.

 

Logically that makes sense to me...
I would've removed the anti-foulers

 

This is my best guess, but a good one. The lengthend bung does not effect A/F at all. What is there is there so to speak. But that being said, the very small hole would keep a lot of the exhaust gas from getting to the O2 sensor. O2 sensors need to be in the airstream to get hot, and to read correctly.

In addition since the hole is small there could be a significant delay from when the A/F changes and when it sees it.

In summary, it's a very bad idea. Sticking it in the tailpipe would be much better.