gm.trqeng

[dian]

99 c5. what are the inputs for torque in a stock tune? what happens if you loose the maf? and how is it with cos3 and (e.g.) a 2bar map?

(gm.trqeng seems to yield same values as gm.trqtrans. any thoughts on that?)

edit: this is what im seeing at 200kpa/no maf. (i cant upload scan for some reason.) rising ibpw to redline, dyncylair rising to redline (1.90 max), torque peaking at 3800* with a (quite realistic for max) value around 800 nm, acceleration fluctuating but highest at 5000-6000, calc.power rising to redline with 500 rwhp max (not unrealistic, a bit low). in a stock cofiguration i see max torque at 450 nm (engine rating is 475).

*140kpa

[nonnieselman]

Ive never tuned a MAF for boost so i have no idea on this one.

[dian]

speaking of dyncylair: its seems overreported by about 40% in the cos3 tune.

stock car reports 0.71 g at torque peak. 0.721 liters x 1.175 (15 degrees c, 300m, 50%) is 0.846 g, working out to 84% vol. efficiency. cos3 reports 1.71 g at 5500rpm/190kpa*. 0.721 liters x 1.117 (30 degrees c, 300m, 50%) is 0.795 g x 1.9 p.r. = 1.51 g. 1.21 g at 80% efficiency. 1.71/1.21=1.41. it would mean 113% cylinder filling.

any thoughts on that? if the inputs were known the numbers could be somehow scaled back, i guess.

*i took this point because the 2bar map is still well within its range.

[joecar]

GM.TRQENG and GM.TRQTRANS should read the same for combined engine/trans PCM.

[joecar]

When MAF fails PCM sets a MAF DTC, sees this and then does SD (VE table) only.

[joecar]

So you need to get both MAF and VE tables corrected.

[joecar]

In COS3 are you MAF-less (i.e. SD, VE only)...? How did you verify this (or not this)...?

If SD might have to look at temperature correction airmass tables.

[dian]

maf is gone.

so are you saying the ecu looks at map and iat only to calculate torque/dyncylair? (obviously it understands boost wit cos3.) how does it then happen it thinks they are highest at low rpm/bosst (3800/140kpa)? iat* is the same and i surely do not have the largest v/e numbers in the midrange, they are rising up to redline.. a stock car reports highers tq/cylair around 5000 btw.

*in both cases maf would be well beyond the 120g/s blending table limit

[joecar]

ECU first calculates airmass using MAF and/or VE, it then calculates everything else, including fuel mass and ignition advance.

[joecar]

Are you getting a MAF DTC...?