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Old 09-26-2003, 02:25 PM   #4
Scooby Guru
Member#: 12454
Join Date: Nov 2001
Chapter/Region: Tri-State
Location: Vermont
10 Toyota Taco
K8 SV650SF

Default Re: Hi

Originally posted by chuglobal
1. There are 2x O2 sensors stock, one in the exhaust manifold and one right before the 3rd Cat. How would the part between the exhaust manifold to uppipe see positive boost pressure? The Vishnu catless uppipe has a bung for a wideband O2 sensor, I would deduct that they put it there for a reason?
2. How does running too rich cause knock? Do you have a "theory," I just heard that it through the "grapevine."
3. Humm I thought the wideband O2 kit for the UTEC from TurobXs would be a little cheaper in the $300+/- range.
4. What is a good practical procedure in tunning: boost ( obtain desired boost level ) > timing ( reduce knock if necessary ) > A/F ( decrease for optimal performance but no too lean ) > timing ( advance as much as possible w/ out knock and watch A/F change )?
5. Does changing timing ( advance/pull ) cause a change in A/F ratio?
Yeah there are two 02 sensors right, the ghetto wideband one in the exhuast manifold reads incorrectly because it is subjected to boost pressure, the reason why the UTEC logger just says rich after about 12:1. If you mount an wideband sensor in the upipe, thats just downstream from the exhuast manifold so the same thing would happen IMO. It has to be after the exhuast comes out of the exhuast side of the turbo like where the 2nd 02 sensor is by the 3rd cat.

I don't know why adding too much fuel can cause knock enough to explain it technically.

I've never had the chance to tune with an wideband so I don't know if it causes a change in the a/f ratio. I know it can cause a change in the EGT reading though, but I think that the a/f ratio stays the same. (which can make tuning with EGTs decieving sometimes)
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