VE PID and HP curve?

[ZUKI]

How accurate is the VE PID?

1st question: If your MAF was accurate, wouldn't we want to set our VE table as close to this as what it's reading? My VE says about 21% at idle. How would GM get such a higher number? I think it's in the 50 range. Then under WOT it maxes out arounf 87% which isn't too far off. But the lower RPM and MAP one look to be way off.

2nd question, how closely do you think the VE curve would be to your HP curve read from a dyno? Mine climbs until arounf 5500 RPM then starts to fall off(along with DCA). If you get alot of 100% TP data from your different logs, and do a scatter chart with VE and RPM, you see a nice little curve goin on. I'd be interested to see how close it would be to the real HP curve.(anyone got dyno info for their car to check it out?) You could possibly use this to figure your best shift points. I know timing and fuel would skewed it a bit, but I'd think it would be close.

[Chris@HPTuners]

the VE PID is a ratio measure of calculated airmass (MAF/VE table etc.) to an ideal airmass calculation the PCM makes. It is used in the misfire tables as a measure of load.

eg. check the top axis of the misfire tables.

I will probably rename this to Misfire VE or something else in future to avoid confusion with the actual VE table values. (although this value actually is VE in the true sense).

[nbmls1ta]

Chris,
Could we use the VE PID values to replace our VE table values? You said they were the VE value in the true sense so could we just put them in the table. I have a cam and headers so would the VE PID values be the "correct" values for the VE table?
Thanks
Matt

[Chris@HPTuners]

no, the VE PID is actually calculated using the output of the MAF/VE table.

[ZUKI]

I'm not sure I follow. How is the VE table used? I thought it was used only as a reference to check for MAF failure, and to be used as a base for MAF failure. I know there were a few formulas around that used the MAF reading, IAT, and a few other things to figure VE. I thought thats what the VE reading was. I guess not. Can you explain exactly how that VE PID is reading/telling us?

[Chris@HPTuners]

see my earlier post. calculated airmass / ideal airmass

calculated airmass is a result of the MAF and VE table.