maf testing

[Lego]

ive been voltage testing my hitachi maf, im getting .8v at idle and ive gotten up to 5.7v at 14-15psi with my td04, do these numbers sound right? once i pass 5v arnt my injectors dumping fuel?

[Legacy777]

Where are you reading that voltage from? Select monitor, rev scan?

For whatever reason the MAF voltage read by the ECU is higher that 5v. To really get an accurate reading, you would need to monitor both the 5v reference voltage for its value, and the MAF signal voltage with a multimeter or data acquisition system.

[BSOD2600]

As you cross posted this already, so will I....

It was always my understanding the MAF goes 'blind' above 5V. Calculate your injector duty cycle to get a better sense if they're dumping fuel / going static. http://www.stealth316.com/2-calc-idc.htm. On other runs, I'd data log the MAF voltage and MAF air flow to see if they both linearly climb together or flatline above 5V.

[Lego]

ive been testing it with a multi meter.

i only cross threaded because i wanted to see if mike would chime in.

i went to 15psi today and got 6v. i didnt think the voltage goes past 5 since it maxes at 5?

[BSOD2600]

While the MAF might read past 5V, it only matters what the ECU "sees" and has tables for. With all the data logging I did with various stock/aftermarket components, I believe I made the point that even BELOW the Hitachi 5V limit -- around 4.8V, it makes the injectors go static and just dump fuel. My graphs AFR flat lined at ~10 ARR when the MAF was near 5V. Injector duty cycle only approached 80%, so in theory, should have some extra headroom and not the limiting factor for those graphs.

[Lego]

i have a electronic fuel cut defender that was made by a guy on here, could you use the same principle on the maf so it doesnt tell the ecu to dump fuel? or is it just plain and simple this hitachi maf is hopeless.

[BSOD2600]

... maf so it doesnt tell the ecu to dump fuel?

That requires a tune to readjust the various maps. Thats what the revtronix chip does, or one 'tricks' the ECU to do with the various piggy back solutions.