[b3lha]

Originally Posted by RoughSilver92

Well, my progress lately has been terribly slow. I've been very slowly working on F653 over the last couple weeks. The rev limiter is easy to understand since the work on that has already been done by others. It looks very simple to make a "launch control" for the manual transmission people. It looks like 86c7 and 86c8 rev limit thresholds are used when in p or n. Probably not the most ideal launch control with the hard fuel cut, but an option nonetheless.

Yes. The trick to making it work properly for launch control is to reduce the hysteresis from 100rpm to 50 or even 25. It would also allow for "flat foot shifting" because it would limit the rpm whenever the clutch is down.

Originally Posted by RoughSilver92

I'm still trying to wrap my head around what's happening in the rest of that block. What keeps messing with my head is
<code>
Ok it doesn't look like much but the bulk of the function (f6b5-f813) is only executed if:
(speed = 0 and the throttle is closed )
or
(speed >= 10mph and the throttle is closed)

Just seems like a weird set of conditions. I guess now it is time to see what the values this function affects do (1340 11dd 10d1)

I completely agree with your analysis.

Figuring out why it does that is another matter. Speed >= 10 and throttle closed suggests maybe something to do with overrun fuel cut?

Looking through the rest of the function I can see it looks at the torque control switch (gearchange fuel cut?).

Later it looks at some 2D maps based on coolant temp. (Possibly overrun fuel resume rpm based on coolant temperature). Maybe worth extracting them into excel and plotting a graph to see what shape they are.

I suspect that this function is all about various sets of conditions for fuel cut and resume. But I'm just guessing, I haven't studied it at all.

Originally Posted by RoughSilver92

Oh yeah, this may seem like a stupid question, but does the ecu see reverse speeds as negative? The reason I ask is there is a place where it asks if 1071 (speed) is >= 0, so weather or not the ecu sees reverse as negative would determine it the other path is ever seen in reality.

The speed sensor produces 4 electrical pulses per rotation, but it has no way of knowing or signalling the direction of rotation. So speed is always positive.