GuitsBoy

iTrader: (4)

I was wondering if someone could do me a favor. Ive seen pictures of what looks like a resistor spanning two bars on the Budget GMAF. Could someone please read me the color code / value for this resistor? Im trying to see if this will give me some clues as to where to start with a project im working on. Im trying to find an inexpensive way to modify ported MAFS to report slightly higher than they do after being ported. Hopefully this will help aleviate the lean condition after porting '01 and '02 cars.

Basically Im trying to use a resistor to draw additional current to make the MAF think that it requires more current to keep the hot wires at the proper temperature. The MAF should then report it flowing more air. I tried blindly with ATAP and a few large value pots, but id get to a point and just kill the engine. If you can tell me what resistance to start with, it would make the trial and error go much smoother.

Thanks for any help!
-Tony

Team ZR-1

Only about 30 Ohms, use a smaller resistance pot
to the center and one of the ends that have the heater

GuitsBoy

iTrader: (4)

First off, thank you so much for the reply. Its been tough finding anyone who wants to help with this over on that "other" board.
Are you saying that the resistor on the budget GMAF is indeed 30 ohms? Or is 30 Ohms the resistance of the heater itself? IIRC Whenever using a pot with anything less than 25K Ohms, the car would just die on contact. I figured Id need to run a resistor and a low resistance pot in series to make it somewhat adjustable.
I dont suppose anyone has ever done this before. Id hate to re-invent the wheel.

Thanks again!
-Tony

GuitsBoy

iTrader: (4)

ttt

Team ZR-1

Sorry that should have been about 130 Ohm across resistor when it is soldered as shown



Just take a freq counter, measure output of stock one and
then with a small Ohm pot experiment and see how much less the freq
is that you want to calibrate MAF to PCM MAF table.

GuitsBoy

iTrader: (4)

Whos better than you, john. Thank you so much for the pic.

I assume that the resistor in question is at the top of the two rightmost bars. I cant quite tell from the pic but it looks like the bars have been cut and bridged across? Is that the case? If so, I cant think of any reason for doing this.

Also, you say "about 130 Ohm across resistor". Was this ascertained by reading the color code (Br. Or. Br.) or was this measured with a multimeter to the two bars. If the latter was the case, Ill have to take into account the resistance of the original heating element.

Sadly I dont have a freq counter on my multimeter. I do however have autotap which should be able to display MAF frequency, so I plan on using that. Ive never looked at MAF frequency before (never needed to) but lower Hz = higher airflow?

Over the weekend, ill attach some aligator clip extensions to the bars and run them out under the airlid. Ill experiment with some different small resistance pots and some resistors I have lying around. Hopefully all ill have to do is watch the MAF Hz and see hoe the different values effect the car. If I find one that looks to be in the neighborhood of 20% or so, Ill button her up and go for a leisurely cruise around the block and hopefully get the LTFT's back down around zero. Even if I cant get them back to zero or negatives, I can tweek the rest using a MAFT. I ran out of adjustment on the MAFT otherwise I wouldn't have needed to try this in the first place.

Again, thank you for all the help and advice!

-Tony

Team ZR-1

Yes the resistor is at the top on the left and yes the aprox 130 Ohms was measured across the two posts.
In this case it is a stock 01 Z06 85 mm MAF that is reducing MAF output to match a MAF table that was configured for a 75 mm MAF.
Yes you can do the compare with a PCM scanner for MAF frequency and then adjust the pot to dial in what is best for your engine setup, then measure the resistance and replace with a single resistor in place of the pot.