EFIDynoTuning Forum

I have a long term project, 96 4.6L using QH on CDAN4 PCM. I recently installed a Vortech charger (draw through maf) and to prep for it, I installed 39lb injectors and a 80mm lighting MAF. On motor, I dialed it in pretty good however, with the charger, the maf voltage hits 5 v before the shift point. I have the top table (FN0361) voltage at 5.120 which if I write a higher number, it goes back to 5.120. Also the MAF_HI_ER is set at 4.900 volts. I know I should change to a larger maf but, I would like a workaround if possible. Can the MAF_HI_ER be changed to 5 volts or even 6 volts? The maf sensor can easily read above 5 volts but can the PCM read and act upon a higher voltage. The engine still runs fine but starts to cut back on the injector PW during this over voltage which is a second or two before the upshift. I'm willing to experiment but I hope you guys might know a fix, thanks.....Ken.

No it cant the maf works on a 5v reference.

A diablo mafia increases the 5v ground reference the ecu feeds the maf to 7.5 volts or higher and then scaes it back down to 5v to increas the mafs measuring abilities so thats an option for you but it requires a very stable electrical system as any voltage variations will cause instabilities.

You can set the backflow region switch and use the backflow functions to disregard the maf and run off the inferred load table above an rpm and throttle position.

Thats the only accurate way of handling it. Simply populate the inferred load table with sane values and your golden.

Thanks for the info. I don't see an inferred load table in my program so a bigger maf sensor is likely the best fix.

well yeah

badshoe wrote: ↑2021 Mar 07, 13:55 Thanks for the info. I don't see an inferred load table in my program so a bigger maf sensor is likely the best fix.

Load w/ Failed MAF, FN1036A or Peak Load at Sea Level name(s) might help.

I think FN1036A and B is for engines with intake runner control which is turned off on mine. I believe that would correct my concern but I think that table isn't looked at on my tune. However, the FN1037 is a load subtract related to TPS/RPM. Setting all the upper cells to zero might do something. I can't find a Peak Load at sea level on mine.

yes it is hence the inferred load table i reference above

fn1037 is inferred baro pres correction for inferred load its not going to do what you need

peak load at sealevel is fn035 which is for perload. Thats irrelevant to what you trying to do.

So if I put the load values of what it is just before the maf tops out into the FN1036A-B upper right cells, do what I need?

see 7 posts up

Thanks.