4" intake piping - 95MM MAF Tuning

[charlay86]

Yeah. the tables have a 0x1FFF (8191hz) range, starting from the minimum frequency 0x762 (1890hz)
8191+1890=10081hz

[The1]

thanks, that's what i thought, im just thinking it's this MAF i can't be sure what the specs are, but it is a 95mm and looks identical to LS2 ones. I guess if i owned an oscilloscope it would be handy to see what's it doing

[VL400]

The VS code is the same as VT in that the data stream gets the raw airflow value, you see whatever the PCMs see's. From there its scaled and limited to the 8kHz range like charlay86 has shown. If you can borrow a scope it might be handy to confirm the wave shape, if you were over this side could have also used a logging fluke meter while giving it a fang.

[charlay86]

VL400, have you any idea what the highest frequency the PCM can reliably handle?

[VL400]

It looks like 16384Hz is probably the max and seems to be stable at anything below that, after around 16KHz it drops down and goes a little screwy. 40KHz it flatlines at 0.

Only had a VT PCM handy but should be similar to VS I would have thought..

VT MAF.jpg (107.37 KiB) Viewed 4385 times

[The1]

yeh i need to get a scope. been meaning to get one for years, even got new probes still in new packets

[The1]

it's no oscilloscope but my multimeter has a logging feature, would be very inaccurate but though id try it, log attached. manual says it's range is upto 400mhz with a 10hz resolution upto 40khz, i imaging the response time etc wouldn't be very good. The 5000hz flick was approx 3500rpm and the 13-14000hz was redline. I Dont think that can be right there'd be noway a v6 would max out a ls2 MAF.

[The1]

ok had a play with my new oscilloscope, Hopefully did this measuring correctly , i got ahold of some other MAF's to play with, i think the MAF i have is an aftermarket as there no delphi stuff on it anywhere, actually no labeling at all, i managed to get ahold of a geniune Delphi MAF and another one the same as this stuffed one to play with.

I used the aircompressor from a distance to blow air through the MAF's, seems as you would expect when they reach there max flow it just stays at the same hz output and flatlines.

Here's my bench setup, just a standard AT psu used to feed 12v to the MAF, the scope on the output

MAFBENCH.jpg (113.97 KiB) Viewed 4327 times

Stuffed MAF, after about 50psi i keep going to 100psi but it doesn't register anymore than 7576hz

stuffedmaf.jpg (55.71 KiB) Viewed 4327 times

Here's the second aftermarket one i got ahold of which seems to goto 13160hz no problems.

GoodMAF.jpg (55.17 KiB) Viewed 4327 times

And here's a genuine LS2 MAF with Delphi Badge on it, got 14710hz, going by the LS2 MAF tables there only used upto 12000hz

GenuineLS2MAF1.jpg (51.09 KiB) Viewed 4327 times

GenuineLS2MAF2.jpg (57.63 KiB) Viewed 4327 times

Compairing the two seems the aftermarket has bigger voltage from peak to peak than the Geniune one which seems much more refined?

I have been using the Genuine MAF in the car now and have had no flatlining issues, i have changed my tuning ways as it seems after you get about 30% variation over the stock MAf tables things go a bit weird, im thinking there's other factors at play with the MAF not just MAF tables, so now i have been adjusting the base injector rate instead while using the stock tables to bring it close, then use the MAF tables to tweak it. Once ive finished it all ill post up some bins with the aftermarket and Genuine for reference.

[The1]

did a run with the genuine MAF hooked up, the Genuine MAF runs pretty much the same tables but just has extended range, so i left the tables stock and adjusted the base inj rate to 290ms/gram which brung it 10% ~

The airflow over stock MAF increased as well, moreso in the 50% up range.

Stock MAF

LS2 MAF

Log with 290 inj set, stock MAF tables.

test genuine ls2 maf stock tables 290ms gram inj.xdl

(596.64 KiB) Downloaded 276 times

[VL400]

Nice testing The voltage levels look really low though, it might be an open collector output on the MAF so a pullup resistor to 5v would help get a nice output. The factory input circuit is like this...

FMAF.jpg (34.27 KiB) Viewed 3805 times