Just like the title states......

How accurate will my wide band readings be if it is run open header?

 

well if the o2 sensor is still in the exhaust flow and not being diluded with the outside air it should be the same.

 

That is my concern, is it going to be diluted by outside air since the bung is so close to the end of the header.

 

It reads leaner if you run open header. I don't remember by how much, but it was quite a bit.

 

Under full throttle there *should* be enough exhaust flow to keep air out of the pipe. But under light throttle that may not be possible. Is there anyway you can move the sensor?

 

Makes sense.

I think I remember how it was on mine. With the full exhaust on, it would idle around high 14's to 15.0:1. Idling with open header, the wideband would read around 17.0:1, but I knew it was a false reading b/c it would have been lean misfiring if it really was that lean.

 

Interesting. I may want to hook up at least a 2 foot section of piping then to prevent this. I don't want to have to guesstimate the difference.

 

the AFR readings were always at 19s for me thats way friggin lean when i was open header, the bung was 2-3 in from the tip. dont even bother man i had to get an exhaust on there just so i could have the proper reading. dont risk your motor just wait until you get a full exhaust.

 

I don't want a full exhaust- that is the thing. It is a track car only.

 

What kind of header are you using? I've got a 2.5" OD 3ft stainless race pipe w/ turndown I need to part with.

 

Really???

What would you like for that piece shipped to AZ> I am very inerested. :-)

Thanks for the heads up by the way.

P.S. It is a custom step header Randy did for me. It does exit into a megaphone though. I need to measure to get the exact exit diameter.

-I just read your PM... Thanks for the tip. I actually have some 2.5 piping here in the garage. I just need the turn down.