Rich at 0% throttle high RPM on track

Hi All,

My first real post. Have completed most of the courses now and getting ready to use the dyno for the race car for the first time.

The car is Hayabusa powered.

Prior to getting on the Dyno Ive been checking my logging from my track runs.

I have attached the file in question. What Ive noticed that whenever I accelerate for any length of time and throttle position can be 100% or less once its goes back to 0% the Lambda hits its full rich reading. Which is 0.673 in this case.

Basically is it a case that I have too much injection or is it the fact that limited oxygen is now going through the engine and the Lambda is seeing the lack of oxygen in the exhaust.

The fuel table looks smooth as well so nothing weird there. I cant see any compensations that would cause this either.

I have a car with a GSXR 1000 engine, controlled by a MoTeC ECU. I see similar behavior closing the throttle at 11,500 RPM, the MAP goes to < 25 kPa, Lamba .7

Quite honestly, I have never worried about this. If there is actual extra fuel, it won't hurt the engine (probably cools it slightly after a long straight WOT run), and I don't care about the power (otherwise I wouldn't be using 0% throttle).

I do have Engine Overrun enabled, and I'm not quite sure why the injectors aren't completely off (8% duty in my case). I'm sure it's to due to the Efficiency table values.

Part of the issue is that it's all but impossible to accurately tune the 0% throttle cells at high rpm. For a TPS based map you will also see the fuelling fall away quite sharply at closed throttle as rpm increases which I notice you aren't doing in your map. This can get tricky juggling the resolution of the table values though as you can end up hitting 0% before you get to the rev limit. My guess therefore is that the light load high rpm areas of the map have probably not been optimised in steady state and instead you've followed some general trends through the map (which by the way is absolutely fine). This can end up with the effect you're seeing which, as David mentions, really isn't necessarily a bad thing for a race engine as it will help cool the engine.