kevin Dubois

alright, thanks to some help from people to determine one of the pin hookups i got the thing to work. it turned on first time, and measured the RPM and throttle position correctly, but the air flow readings were reading funny. i found out that it was because i had the thing set on "flap" type afm sensor, when in fact the barn door acts just like a hot-wire type sensor as a 0-5V increasing voltage signal.

the only unusual thing i noticed was that the % flow rate maxes out at 63.9% instead of 100%. i'm pretty sure there are settings for this, i just haven't gotting to play with it that much. I purchased the thing in anticipation of the ZT-2 wideband so i can tune using that on a dyno, and make changes easily on the street.

there wasn't much info on people who have tried it but from what i did find, it should work just fine. as so far it does...

all in all it took about 3 hours to determine which wires to use by checking the wiring diagrams and waiting for responses here, and it took about 1 hour to install.

i will give a detailed installation process once i figure out which wire is the knock signal wire. that is the only thing i don't have hooked up yet.

doze905

do you think you could use the apexi with a maf set up? without the normal control box that does the maf to barn door conversion?

Mike Murcia

Congrats Kevin! I've got the AVC-r and I'm looking to get the S-AFC. With both of these, a WB O2 and a road dyno, you could tune whenever you do an upgrade. Some feel the Apexi units are rice, but they are pretty powerful tuning devices.

Sam Lin

Doze, you can use the SAFC to do the signal massaging to allow use of a generic MAF. You do still need to choose a MAF from an application that's reasonably close to the right size/flow of our engine, but after that, it's definitely doable, I've seen multiple 944s do it.

Sam

kevin Dubois

yeah, i saw something about using a MAF from a mustang with the AFC and that the flow is similiar as well as the signals being about the same. i would assume that the MAF from the mustang uses the 0-5V increasing signal, and can be easily adjusted with the AFC. i think i am going to do some research into that this week and see what can be done. if so, the mustang MAF is like 75 dollars tops, and with the AFC it is a MAFconversion for less then 450 dollars, with more adjustability then any of the MAF conversions on the market.

doze905

i know someone who can tell me all about mustang MAF systems, i will ask him and post later today. so the 944 barn door system is a 0 to 5V set up?

Sam Lin

Yes, the AFM is 0-5v.

Sam

kevin Dubois

sounds excellent doze! keep me updated.

Danno

Stock AFM actually goes from 0-4.6v...

Dave

Considering the electrical system it these cars, I have to wonder if that 4.6v is intentional or just what happens when you want 5v from a 944!?!
This sounds like it has a lot of potential, but if our flapper reads so close to the same as a MAF, than the MAF should be plug and play or just a minor tweek of the maps. Somehow I get the feeling that there's more to it than a 0-5v output, I suspect the output voltage is not linear for one or both devices.

kevin Dubois

but even if it is not the same path from 0-5 V the AFC will compensate for that by tuning it on a dyno with my wide band O2. sound be able to get pretty strong numbers if i tune it right...

Danno

"but if our flapper reads so close to the same as a MAF, than the MAF should be plug and play or just a minor tweek of the maps."

It's not just the voltage-ranges and low & high peaks you have to account for, but the measuring capacity and shape of the curve. The AFM has a fairly linear airflow-to-voltage curve, while the MAFs have a log-scale curve. Also the actual airflow-to-voltage is differnet due to the max-flow that can be measured. At 4.6v on the stock AFM, you're looking at about 350CFM. No use getting a MAF that will max-out at the same flow-rate as the stock AFM, so a larger MAF that can measure 500CFM may send out 5.0v at 500CFM and 4.6v at 425CFM. If you send 4.6v into the DME, it will look up X-amounts of fuel (duty-cycle). However, this fuel will only match the stock AFM's flow of 350CFM at 4.6v. With the MAF at the same voltage, you've got 20% more air-flow, so now the fuel doesn't match. It's not as simple as putting in a signal-massager in between the sensor and the DME.

I prefer to have a MAF+chip only upgrade like the APE kits. The chips are precisely matched to the sensor. In the example above, the data-cell that is referenced by 4.6v will contain a fuel-value that's 20% richer to match the flow-rate of the MAF.

doze905

i talked with my friend about the MAF set up and he says danno is right on and most mustang MAFs should work. but the SAFC my not be adjustable enuff to make the signal work you may wont to look at some thing like the lindsey racing MAFTERBURNER and use it with your own mustang MAF.

Sam Lin

I gotta admit, I'm still confused why people don't just get the Lindsey S1 MAF and be done with it. None of the other alternatives including DIY will get you a MAF running engine for that low cost.

Sam

ThE sPaCeCoWbOy

I tried to get the AFC working in my 944 and didn't get it working.....do you have a wiring diagram and/or what pins from the ECU you hooked up to what wire?

Thanks,
space