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I have a GT-R on an m150 and there is one area I am having trouble with. Coming to a complete stop as the car transitions out of overrun and back into idle and is downshifting into either 2nd or 1st there is a momentary rich spot where I see a lambda of around 0.8 and the aim is 0.93
It’s an odd spot between overrun fuel cut transitioning to idle. Haven’t gotten a good log of it yet and will try to.
Beyond just tweaking the VE table any other suggestions to smooth the transition and avoid the rich spot?
Also the car is on 282 cams and 6X Id2600x injectors so a lot of fuel comes in at once.
it could be the VE, since that is a very hard spot to get to on the dyno. However, before changing that...
This should be tuned by changing the value of "Fuel Film Primary Offset" or "Fuel Film Secondary Offset". See the help for "Fuel Film", as it explains the whole process, and mentions specifically adjusting that offset value after an overrun fuel cut.
Thanks - I had the laptop with me in the car today with m1tune open and it looks like this is whats happening
1) Goes into overrun fuel cut
2) Comes out of overrun fuel cut and into overrun pedal as it decels to idle - at this point the lambda target is 0.93 but the car is reading lean as its coming out of fuel cut and thus the m1 starts adding fuel
3) Transitions into idle from overrun pedal - it goes really rich until the m1 stair steps out the fuel it added in step 2 for 1-2s and then idles fine
I have an 80mb log I can share as well or trim down, but here are some pics from M1 tune for reference
Added a trimmed log if that helps. This is new GTR Firmware that has more advanced overrun, looks like the behavior is a bit different when it fully reaches overrun fuel cut versus only overrun pedal
So I think I got it sorted as I was able to take it for an extended drive with some stopping points to make changes on the fly and then try again. I basically turned the Closed Loop off below 50kpa or so and was able to adjust the VE table to get closer to the target in the area between overrun and idle. With the ID2600 injectors a small change has a pretty big impact so found a happy spot.