question:
the early MAFs 85-89 used a small diameter
housing, why not use a 93-2001 MAF?
i know there has got to be a frequency conflict
to the computer, but couldnt a buffer be built
to compensate?
all the talk ive heard was that the earlier
MAFs were so restrictive and the later models
received a larger bore. why cant i run these
on an earlier system?
any previous experiences?
airdeano

 

From what I've read here on the board, the technology is totally different. Someone was working on an interface, but I have not read anything either way on how it went.

 

It seems pretty straight forward to implement, as the older style MAF used a voltage to indicate airflow, while the newer ones use a frequency generator. An interface could be constructed, I think I can spin up something that will work, but I would need to know the exact details of the operation of the newer style MAF(frequencies vs airflow, pinout, etc.) If anybody has that info, I'd take a look at what is involved.

 

ive got a pinout diagram 89 y body and
97-2002 pinout f/y body. ill get it jpeged
and send it.
ive got access to a gm tech2, gm tech1,
3 CNC VF7 and i can program to help out.
i know that the 3rd gens would like
something like this!!
i know there at least a flow rate difference
between the two (less restriction).
lemme know
airdeano

 

yeah, any info would help out. Changing the airflow to a larger MAF has gotta be a positive thing, I think that it would just be some analog circuitry to make the newer MAF's work(frequency to voltage conversion, scaled to give 0 to 5 volts over full range), and then a prom rescaling to compensate for more airflow. Once i get the specs on both parts, I can dig around and find the right components that would work, and spin up an application diagram. If you want to sent the Jpegs to me, my email is jwscab@aol.com

 

Died.

 

The scaling from one to the other isn't a linear deal.

 

well, what I've got so far is a frequency range of the new style(500Hz to 12kHz), and I know that the older style uses 0 to 5 volts. Using a frequency to voltage converter, an LM2907, I was able to come up with values to correlate these two. If you have the endpoints defined, wouldn't you be able to linearize the response in the tables? It seems that the tables already do that, otherwise, calibrations wouldn't be necessary, and computers could be simplified into a N-alpha type systems. Does anyone have a table of airflow vs. output voltage(old style) and airflow vs frequency(new style)to see how badly the responses compare?

 

I'm pretty sure the old ones also work on frequency. And even the new ones give a voltage reading that varies with airflow, or so a scanner seems to indicate. It doesn't matter anyhow as you can't give a direct realtionship to the ecm. The ecm will only flow to 255 grams per second so even if you had a MAF that could/would flow more the signal would have to be cut down. That's what a MAF translator is. This has all been covered before at the DIY PROM board, many times in fact.

 

I have to apologize, since I'm not exactly familiar with the tables avaialble for the MAF operation, but it still follows the typical lookup table methodology. The units on the tables are arbitrary, so for instance, if the MAF happens to be 255g/s(max flow) then it just so happens that the device flows to the nice 8 bit number, and the g/s is one for one. But say now, you have a device that flows 500g/s at full flow, now you'll have to double your fuel map, and the map becomes slighly less accurate becuase you've doubled the g/s values. Maybe I'm kicking a dead horse, but this shouldn't be a truly difficult thing if the tables can be manipulated.

 

No, you're not kicking a dead horse. As a matter of fact a lot of guys wuld be greatful if you came up with something as most guys that are exceeding the 255 limit have to go to speed density. The conversion you speak of is possible and is in effect with the TR crowd. You're right in that you lose accuracy (resolution) but it's a small price to pay. Basically it's a two part deal involving hardware and software and the reason it hasn't been attacked harder is becausde there is an alternative in going to speed density but not so for the TR guys.

 

Haa,
Haaa,
I say.
Just a matter of time before there is a MAP'd 148.

If you'd read my latest work on the Turbobuick.com bulletin board you'd see also where I got a MAF to be about as free flowing as MAP, correctly