V666

I posted this also in the forced induction section with no answers yet.. I have a lq4 with a pt-88 with a 4" downpipe with a 4" exhaust cutout. So I originally was gonna run the stock ecu wich would use narrow bands on each header. plans changed now gonna run a Holley Dominator or HP which uses only wide band (correct??) Problem may be...if I am running a wide band o2 sensor for the Holley what do I do if I wanna open the exhaust dump? I read I cant install the wide band (or bands) before the turbo. My 4" downpipe Y's right outta the turbo into a dump pipe down about 18" to the electronic 4" cutout. Any help would be appreciated

wait4me

iTrader: (10)

The reason for this is because your wideband will see fresh air from the dumps, causing it to think you are running lean and will make your engine very rich.

You can turn off the correction temporary if you want to open the dumps. Most of the time though, if you have large enough diameter exhaust tubing, and good mufflers, the dumps shouldn't show much of a gain.

You could just run the dumps farther down away from the o2 sensors as well, and put in a glass pack or something to disrupt backward exhaust flow.

chub406

I am doing the exact same build and have asked the same questions. On a trubo car, I read the same thing on the wideband. I wanted to have one on each bank but not after reading that. If you are only opening it at the track. There wouldn't be anyway of it reading off would it? The exhaust flow I would think wouldn't allow any air coming back in.

V666

The problem seems to be for me that with the dump open the wideband o2 would be in the exhaust side of the Y and not reading the exhaust flow out of the dump tube. I did not plan for it accordingly and now not having enough downpipe before the Y to keep the sensor far enough away from the turbo housing for overheating the sensor. I wonder if I can run a second sensor in the dump and run a switch to toggle between the two somehow? Unfortunatly I did not realize I couldnt run wide bands in the stock narrowband locations before the turbo. Any ideas?

Slowhawk

iTrader: (12)

On my car 427ci/88 I run 1 wideband in the downpipe about 1' from exit.
No problems tuning it and I run the stock computer making well over 1k rwhp.

V666

slowhawk are you running a dump pipe on your car? I would like to keep the quieter 2 1/2" dual exhaust for the street and run my dump setup for all out performance. Any thoughts or info on how I can easily wire up two wideband o2's to a switch or???