Digital MAF Scaling

[kidturbo]

Working on a way to run dual digital MAF units on a E35B. Basically taking two MAF sensor signals and combine those values into a single output with a total fed to ECM.

To do this, I plan to use the new style [and cheaper] GM 15865791 MAF. Some guys over on a Corvette Forum thread mapped out some higher flow range options a while back. However our E35B - B0205 table tops out at 8696Hz, while the new MAF produces up to a 12,200Hz signal. EFIlive limit is 1000G/s, so we have plenty of scale left on that side. Needing a Cax file to re-scale the MAF table.

I've done the ground work to verify everything else should work. Using a square wave Hz generator to check the ECM limit, found it will recognize up to 14818Hz input value. Well within the newer MAF range. However, once that value exceeds 9.2k Hz, the G/s PID reading falls off to zero. Which tells me it would likely set a MAF out of range code. So looks like the B0205 table is our only issue. Values shown in pictures attached.

I posted a request on the EFIlive forum, but figured better chance someone here could help with writing a CAX file.

Tks

 

[DAVe3283]

If you are combining the two signals, you can always have your chip only output in the range already mapped in EFILive, and just rescale the g/sec value to match what you program in to your chip.

Not necessarily ideal, but might be much easier than trying to get a CAX to patch the axis values.

Sent from my E5823 using Tapatalk

 

[kidturbo]

That's certainly a good option to consider, just set a 9khz max output to the ECU. Easiest I've came up with so far would be just run one MAF on a single turbo, recalibrate scale to double that value and would likely be dang close most of the time.

Plan was to do a nice nice unit with a 15khz output range, that can also set a performance code if a MAF reads out of sync for XX seconds. Maybe light an LED on that MAF plug to identify which bank is lagging. Limitless programing options.

Since if we have the capability to read 1000G/s, it would be nice to have better resolution to go with it. That table mod would even work well with a single using the newer sensor. But it still requires the upper limit be changed, cause the moment you exceed 9khz input the G/s drops off to zero. The Vette guys were able to get a table changed in an EFI or HPT update. I'm gonna search a bin to see if I can find the matching axis line. Could be a simple edit, I just don't have enough experience to do it quickly or with confidence. Need that roadmap file now