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Toofah King Bad
 
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Join Date: Oct 2006
Location: PacNW
Posts: 3,848
Garage
UTCIS and Lambda

Shaggy, my 931, is getting a digital control pressure regulator. I am wondering if I should eliminate the "lambda loop" (narrow band O2, TPS, digitally controlled frequency valve, lambda computer).

It seems like its main purposes (fine idle adjustment & WOT enrichment) won't be needed with the UTCIS. Since I am having new lines built, I am in a position to cleanly delete the frequency valve. I especially don't want a "battle of pressures" between the UT controller and lambda controller at idle.

Thoughts?
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Old 04-20-2010, 08:26 AM
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There won't be any battle of pressures since control pressure and the lambda fuel head lower chamber pressure are completely unrelated.

If you have emission testing than leave the lambda stuff in there, if not it's up to you.
Old 04-20-2010, 08:35 AM
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Just unplug the O2 sensor when doing your base tuning work. This will disable the Lambda function and lock the frequency valve at a fixed duty cycle.

You could just run like this.

If you want, you can plug the O2 back in and the Lambda will correct around the D-WUR at idle & cruse.

You could replace or add to the WOT switch at the throttle plate with a vacuum switch so any time you accelerate and intake manifold vac goes away the WOT function is triggered and the Lambda function is turned off.

I would probably just leave the O2 unplugged until maybe when I needed to smog it as you will have your AFR's dialed in like you want them and you many not want the Lambda to effect things.
Old 04-20-2010, 09:18 AM
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