SAE.MAF vs GM.DYNAIR_LS2 vs GM.AIRPERSEC

[Gelf VXR]

SAE.MAP = Signal from the MAF

GM.DYNAIR_LS2 (MAFSD BBL DESCRIPTION) = VE Table vales

GM.AIRPERSEC = ?? I assme this is the extrapolated value used by the PCM derived from SAE.MAP & GM.DYNAIR. Generally the higher value of the two..

Can antone confirm?

[joecar]

Hi Gelf, please post any logs containing those pids.

:)

[Gelf VXR]

Hi Gelf, please post any logs containing those pids.

:)

heres one

[Gelf VXR]

Logged another run this morning with MAF only and AIRPERSEC tracked the MAF signal albeit a bit smoother, maybe some internal filtering? The DYNAIR is still there. Log attached for reference.

Anyway, after calibrating the MAF and autoVE with wide bands finding my trims way negative in CL (-10%), BEN's read .96. I am now going to calibrate the MAF and VE table using STFT+LTFT. It makes sense seeing as I am running in CL. My controversial plan is to calibrate the MAF and VE Table to the rich bank to 0%, so the lean bank will be plus 4 to 5%.

I hope then to see 0% rich and +5% lean in normal CL running, which means g/cyl look up for spark value will be at optimum plus marginal advance. My PE fueling should be balanced and equal on both banks, unless I of course the PCM adds positive trims from the lean bank to both banks under PE?!

I not a fan of speed density because you can't adress this difference in fueling between the two banks full stop, you can even hear it in the exhaust note, MAF is much smoother. My 2 penys lol

[swingtan]

I think......

MAF gm/S is the actual MAF measured value after the lookup tables in the tune.

Both the other two I think are calculations from other measured parameters.

For example, I think GM.AIRPERSEC is calculated from the measured gm/Cyl PID. using


GM.AIRPERSEC=RPM/60/2*8*(gm per Cyl) {RPM/60 to get rev per sec, /2 cycles per rev, *8 cylinders, * gm of air per cyl} This give gm/Sec from the measured gm/Cyl ( which is actually a calculation from the measured MAP using the VE table ).


GM.DYNAIR_LS2 on the other hand seems to be a lot different to the other two values. but perhaps it's a direct conversion from the MAP and VE table into gm/Sec instead of gm/Cyl. I'm not sure though.

What I can say is that I created a calc PID for gm/Sec for the E38 and use that to compare gm/Cyl from the VVE to the MAF signal. I run the MAF and the calibration is pretty good, so if the calc PID shows a different value to the MAF, I know the VVE is off. It seems to work pretty well and can be used to help make adjustments to the VVE.

As for your plan, I see what you are trying to do. As the LTFT's won't lean out the PE fueling, you are getting the rich bank "spot on" and allowing the LTFT to bring the lean bank up to the correct levels. I like the idea, keep us posted on how it works out.

Simon.