Full throttle gear change

[mos]

Hi all i have a full throttle gear change system fitted to my N/A. It is fitted to the coil and the clutch pedal. I thought this system worked by cutting the sparks through the distributor but if it does then i would have thought the car would be rich when shifting. However mine runs lean when this unit is working with the throttle wide open. Does anybody know why.

[JamesG]

The lambda sensor measures oxygen. If there is a lean condition then all fuel is burned and the extra oxgen is measured. If no spark occurs, then no fuel is burned and again the oxygen is measured, giving a false fully lean reading.

I don't know much about lambda sensors, but I remember having to deal with this at work for writing an ECU strategy that disregarded the lambda reading during a cut.

James.

[mos]

I see what you mean, because the fuel isnt getting burned neither is any oxygen compared to when the spark is there so it will show lean because you have as much air coming out as going in. Didnt think of it that way, cheers

[Chris Wilson]

Originally posted by mos
I see what you mean, because the fuel isnt getting burned neither is any oxygen compared to when the spark is there so it will show lean because you have as much air coming out as going in. Didnt think of it that way, cheers


That's why a misfiring engine, even a slightly missing one, can give false wide band readings when you are trying to map it. Confuses the hell out of some folks as it's not really obvious until it's explained.