Tuning questions

Mick70RR · Post by **Mick70RR** » Wed May 10, 06 9:52 pm

Beginning to think this O2 sensor is pretty useless without measuring the temperature unless you are aiming for 14.7:1. 850mV would be 14.4:1 at 500 deg C but 11.5:1 at 900 deg C.

Kev · Post by **Kev** » Thu May 11, 06 8:29 am

SteveB. You are correct. The venturi in the secondaries gives an additional signal to the vac can to make sure it stays open as the vac on the primaries will drop when the secondaries open.(

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Dave-R · Post by **Dave-R** » Thu May 11, 06 9:20 am

Err. Steve?

Dave wrote:Found a diagram in a book and scanned it for you mate. Looks like it gets a signal from the secondary side as well.

Dave-R · Post by **Dave-R** » Thu May 11, 06 9:34 am

Mick70RR wrote:Beginning to think this O2 sensor is pretty useless without measuring the temperature unless you are aiming for 14.7:1. 850mV would be 14.4:1 at 500 deg C but 11.5:1 at 900 deg C.

True but...you will normally find that when the mixture starts to get ballpark the exhaust temp will settle down around 800-850 degrees. So I am told.

Then again you can now get these wideband versions (more expensive) that are a lot more accurate. Esp in the richer than 14:1 band.

These tools are not perfect but they get you a lot closer than any other way. After that it is still down to experiance and trial and error untill you feel it is right and the plugs/strip times confirm it is right.

Almost every yank car i have ever tuned has been too rich on the primaries.

Kev · Post by **Kev** » Thu May 11, 06 10:09 am

Right. To prove my secondaries are working I'm off to a private track to fire the Drugs. I'm going back up on the primaries as well as the plugs are a bit grey. I will try my O2 sensor on the AC range and report back.