5volt source needed for the TPS

[rs4pro3]

I thought the afm was powered by a 5-volt source but for some reason on my eta, when I hooked up the volt meter I got 10 volts. Is there just something screwy with my meter, or is there some other easy source to get 5v from?

[RobertK]

What you need is a 5 volt regulator from Radio Shack.. you will need a small piece of aluminum to mount it to in order to disipate some of the heat like a heatsink otherwise it's not expensive and if IIRC the part number is 7805.

[rs4pro3]

hum, I'll have to stop by Radio shack tonight, just checked and the local radio shack has one in stock

[RobertK]

BTW.. I'm not sure what the amp rating is on that wire so check to make sure the regulator you buy can handle the amp rating of that wire. If the amp rating is above 20-25 amps you might have to get a slightly beefier regulator and heatsink.

[rs4pro3]

it's a very tiny wire, so hopefully I'll be set. I already stopped by autozone on my way to class, I ended up picking up 3 of them as the store were closing and they were under a buck each.

[rs4pro3]

Thanks Robert, that worked perfectly. I've got the apexi reading rpm's and throttle angle correctly now. Here is how I mounted up the regulator

Shot of the apexi sitting in the consule

Getting some readings


Now I just have to find a sensor type in the apexi that works with the factory afm, I've tried a few and with them all it's throwing a different sig, back to the ecu and the car goes full lean at 4500. I already now the sensor # for the MAF, but would like to play around with the stock AFM first a little.

[RobertK]

Glad to hear you got it working.

I was under the impression that the SAFC-2 allows you to map out the voltage readout from the AFM and/or MAF and use those readings to create a map that allows you to convert the MAF signal to a voltage signal the DME will recognize.

If this is true this is what I would do is take the voltage read out from the AFM from idle and then at 1000RPM, 1500RPM, 2000RPM, etc. Then hook up the MAF and do the same. Note the difference and voltage and then tell the SAFC-2 to add the difference to each voltage reading on the map.

For better tuning I would take the voltage reading at every 250RPM increment if possible. The more voltage readouts you have for your map the more accurate your MAF tuning will be.

If you get tired of it.. you can always sell it to me ;)

[rs4pro3]

The apexi dosn't actualy have any real mapping ability. It has a bunch of preprogramed inputs and outputs, so you select the one for your car. Then from there is gives you the ability to adjust the output either + or - at any 8 500rpm increments you set. So right now I have it set at
1000
1500
2000
3000
4000
4500
5000
5500
It then has 2 maps you can create, one for low throttle and one for high throttle. So you set the low throttle one for idle and moderate accel, then the high throttle a little richer for high throttle acceleration.
To set you have to an air/fuel ratio guage and a wideband o2, then at each rpm increment start adjusting the curve either + or - till you get the air/fuel ratio you want at that rpm point.

[RobertK]

That explains the A/F meter I see in the picture.

You may be able to better tune it with a wideband O2 sensor.

I don't think anyone has tried this yet but the MAF sensor that Range Rovers use in the late 80's and early 90's have the same connector that the BMW AFM uses except one the the pins is moved.

http://cgi.ebay.com/ebaymotors/Range-Rover-Classic-MAF-Sensor-Parts-Vehicle_W0QQcmdZViewItemQQcategoryZ33557QQitemZ8068631367QQrdZ1QQsspagenameZWDVW

[rs4pro3]

interesting, I'm wanting to use as new as a maf as possible, the old one I had was from an E46 but I damaged the filaments when I was installing my air temp sender. Ya I don't plan on doing any real tuning untill I get the wideband o2.