Motronic question: Amount of ignition advance added during cold run (M30)

[Jeff N.]

....during the cold run cycle?

Story in a nutshell: My 1990 BMW 535i with a fair number of engine modifications (compression change, cam change, displacement change, MAF conversion, etc). The low RPM pickup is better during cold run vs. fully warmed up.

Typically, the cold run cycle will dial in some added advance that decreases with engine speed and that tails out as the engine reaches full operating temp.

Typically, hotter cams benefit from some added ignition advance off cam. I'm guessing that the amount of advance in the cold run cycle is close to what I need to dial in at warm run.

Yes - The fuel mixture is correct at warm run (~13.5:1); car has a wideband sensor in it.

Trying to get a guestimate type figure if the cold run advance amount is like 3 degrees or 15 degrees or ... ?

Thanks for any thoughts!

Jeff

[MarkD]

Jeff,

try adding around 5 degrees @ 1200 rpm, you may possibly want to drop it down to 3 or 4 degrees @ 4k.

The correction map for advance vs coolant temp applies about 6 degrees advance @ 29F, 4 degrees at 45F and 0 deg @ 80F



Mark

[Jeff N.]

Hope things are well your way!

Jeff,

try adding around 5 degrees @ 1200 rpm, you may possibly want to drop it down to 3 or 4 degrees @ 4k.

The correction map for advance vs coolant temp applies about 6 degrees advance @ 29F, 4 degrees at 45F and 0 deg @ 80F



Mark