FUEL

[dj10]

It won't cause the sensor to malfunction. Lead can lead (isn't the english language wonderful?) to the early demise of O2 sensors and catalytic converters though. Your mileage may vary but I've racked up thousands of miles of leaded race gas on wideband sensors before they finally failed. How to tell if one fails? The failure mode is generally to read full lean all the time.

FWIW, no stock ECU that I'm aware of uses O2 feedback at WOT. Closed loop is only used at light throttle. Cruising situations. When you go to WOT the ECU reverts to open loop and runs off a map with no regard to O2 correction. IMO there is very little to worry about in an IT car with a dead O2 sensor. Fuel mileage around the paddock maybe? [/b]

Well I guess I was told wrong. Then this brings up 2 questions. 1. being if you are on a dyno, burning a chip, why does the guy who is burning the chip want the O2 sensor connected or need it connected? And 2, If you are going to burn racing fuel with a slightly compression ratio (as allowed by the rules) should you burn leaded or unleaded. Is this a leading question?
Chris, if you lived in Globblers Knob, Pa you'd probably get a date, or at least a prune.

[C. Ludwig]

Well I guess I was told wrong. Then this brings up 2 questions. 1. being if you are on a dyno, burning a chip, why does the guy who is burning the chip want the O2 sensor connected or need it connected? And 2, If you are going to burn racing fuel with a slightly compression ratio (as allowed by the rules) should you burn leaded or unleaded. Is this a leading question?
Chris, if you lived in Turkey Knob, Pa you'd probably get a date, or at least a prune.
[/b]

The narrow band sensor that most cars use is what I'm referring to. Some makes, and more and more, are starting to use wideband sensors that are more capable but, again, every car I'm aware of only uses O2 correction for less than full throttle correction. That combined with the fact that you'll usually only see about 10% max correction is why so many completely stock cars show overly rich mixtures at WOT. The WOT map is safe rich (low warranty costs) and those throttle settings are never used for EPA ratings (good CAFE numbers for the manufacturer and, oh yeah, your mileage may vary).

The O2 sensor you are probably thinking of that the tuner is using is the wideband sensor. Sometimes called Lambda sensors. Check out this thread for wideband v. narrowband info. http://itforum.improvedtouring.com/forums/...?showtopic=7635 The tuner is using the wideband sensor to see what the actual a/f ratio is in order to know what corrections to make to the tune. It's the high tech way to read plugs and change jets. If he is tuning part throttle settings where there is O2 correction he'd need to see what the base tune is and know the correction factor.

No idea on the lead v. no-lead debate. With modern engines there is no need for lead afaik. However, like has been said, no-lead high octane fuel is expensive. Don't give a hoot and pollute?

[dj10]

No idea on the lead v. no-lead debate. With modern engines there is no need for lead afaik. However, like has been said, no-lead high octane fuel is expensive. Don't give a hoot and pollute?
[/b]

The only advantage of using the 100 unleaded is the O2/WT =3%, where as the leaded has none.