Understanding GM Torque Based ECU's

[Tre-Cool]

So I was doing some searching to try and improve upon my existing knowledge on how these later model ecu's work and found a page on 1 of GM's Patent's which explains how they do there idle control etc and thought it might be worth starting a thread on helpful information for this line of ecu's.

Control system and method for idle speed control torque reserve reduction

The main reason I have found this interesting is because I've been logging my e83 ecu and have noticed since day 1 on the stock tune the car kept running negative timing at idle once the car was fully warmed up and from past experience on the other ecu's (e38,ls1) this generally means it has too much air entering the motor and it's last resort to getting the idle down was to remove timing.

A side of affect of it doing this, is the fuel trims at idle are showing excessively lean and the ltft & stft starts going positive in a big way, I even went as far as modifying the VVE & Maf scale with no difference, so this left me with the assumption that with negative timing occurring unburnt fuel is getting blown straight out of the exhaust.

Not good for the fuel miser.

Unfortunately I don't have the relevant tables I need to try this out with in the program, but I can at least test it out and report back if the tables available in another application do.

[swingtan]

Nice find Dave, I'll need a bit of time to read through that but I have also seen the very low timing in the E39 SIDI. I was able to bring it up a bit by playing with the torque response tables at idle. I may have fudged the torque model as well, I can't remember now....

[joecar]

Very interesting Dave, thanks.

[Tre-Cool]

Another long but good read:

http://www.google.com/patents/US20110139117