SD Tuning on a V6

[arthansen]

I have been playing with this and have a question.

In SD mode, there is no Airflow measurments (all values for MAF are 0). This causes a problem since the spark tables are RPMs vs Airflow. All scaned spark data falls into the one column for 0 MAF. There is no way to accuratly monitor spark

How does the PCM calculate what the spark advance is without airflow (I know it does because it changes within a cell while in SD mode) and how can I monitor it so I know what the advance or retard is in each cell.

I hope all of that makes sence. I have put my SD project on hold until I figure this out (I put my MAF back in ???).

[Missing2]

hrmm, same thing happend to us when we were doing a tune on an LS1..

I "think" its because with out he MAF there is no calulated airmass as we use now (obviously)

So, it will either requier a custom histogram or they have it setup to fallback on a Diferent paramater, that is perhaps getting messed up because you have it logging in table view?

not sure.. probably one or the other..

i will let the pro's explane this one

[Chris@HPTuners]

ya without the cylair PID the histo will not work if the MAF is unplugged. I am working on a fix for this but it is taking a while cos i have to add it specific to every OS we support (which is 100's)

[Missing2]

ya without the cylair PID the histo will not work if the MAF is unplugged. I am working on a fix for this but it is taking a while cos i have to add it specific to every OS we support (which is 100's)

Thats is what i figured,

So, exactly how does the pcm it self go about selecting values from that table? since the cylair PID is not longer available?

???

I am assuning it does it based on a different calculation/PID??

which one?

or am i way off?

[Chris@HPTuners]

the cylair calculation exists within the PCM (be it VE or MAF based). Just that GM didn't make it easy to get it out into a scanner using normal methods. But we have a way around it.

[arthansen]

Great. I think I will just put the SD tune on the back burner until the fix is out. Thanks.