Modifry: very, very interesting results. Thanks for sharing them. Can you develop a calibration table for the EMS based on this data -- or send me the data via email that I can use to do so? The only additional variable that needs to be thrown into the mix is the internal resistence within the EMS unit itself. There, I can't help you, but perhaps GG can.

Best,
Christopher

 

Please do not assume that the internal resistance of the EMS pullup resistor is 2K2. I don't think it is although that is what AEM states.

 

To have an accurate measure of the internal resistance is we need three things:
a) sensor resistance
b) coolant temp
c) what the EMS thinks the voltage is.

I had b) and c) before - now we have a). I should be able to crunch something out when time permits.

Awesome data! THANK-YOU

 

Actually you can do it with a voltmeter and a pot.

Disconnect the ECT sensor from the EMS, turn the ignition ON, and measure the voltage on the input wire to the EMS (should be near 5v).

Connect the pot (5-10k set to it's highest resistance) from ground to the EMS input terminal. Use the pot as a variable resistor, meaning you only use two terminals.

Adjust the pot till the voltage reading at the EMS input terminal is exactly half of what it was with no connection to the EMS.

Remove the pot wire from the ECM and measure the resistance from this wire to ground.


What this does is make a voltage divider using the pullup in the EMS and the pot. When the resistors are exactly equal, the voltage at the mid-point of the divider will be half the total voltage.

 

Hi guys. Any updates on this? Really looking forward to it.

 

Hi Aus,

I'll answer for Modifry, as he and I've been in touch about this. He's getting close -- a beta unit should be ready relatively soon. It's a bit harder than you might think, and I have to give him credit for giving this product a great deal of considered and informed thought.

Best,
CB

 

Not for one second have I thought this would be easy. I have this theory that the only thing that allows people to think something like this is easy is ignorance. I think they are called managers.

 

I've met those guys before!!

I made my usual trek to Charlotte with a prototype installed today. It does work.

I initially programmed it for 180, 190, 200, 210, 220 and 230 for the "bars". I wanted to see "lots of gauge action" so I made the temperatures closer than you might normally. It didn't work as expected.

Well, it did light the gauge up, but the car stays between 187 and 190 on the highway, no matter what speed you do (50 to 80) or if you're going up hill or down, or if you're tromping the throttle for 10-15 seconds. So once the car warmed up the gauge never changed. This was no fun at all.

So I pulled over, whipped out the laptop, fired up Hyperterminal, and sent a new text file to the module, programming the temps for 160, 180, 185, 190, 195, 200.

Yes, you read that right. You can use Hyperterminal and a serial port to send a plain text file to the module to set the gauge transition points. At anytime, even with the engine running. We be shizzlin' now!

Anyway, with only 5 degrees between gauge bars I got more "action", but it was really active if I stopped the car and let it idle. Temps go up to above 200

 

Very Nice to hear.