blockade35

iTrader: (8)

Hi All,

After some tinkering last year I reflashed my ECU to read an AEM wideband through the stock rear O2 sensor pin in the ECU, and read the JDM 3 bar MAP. This year I am adding in an AEM Oil Pressure gauge also and would like to log this through the stock ECU as well. From what I am reading on the evoscan website (http://www.evoscan.com/manuals/Evo%2...U%20pinout.pdf), pin 64 on the stock ECU is not used, but is a 0-5V ADC input. There is no physical wire coming into it, but it would not be too hard to add a pin into the connector (http://www.digikey.com/product-detai...319-ND/2044230) . My thought here is simply add the 0-5V wire from the gauge to pin 64 on the ECU, tell evoscan to read MUT83 as the oil pressure, and scale the 0-255 by 150(PSI)/255 and I should have a loggable oil pressure signal through the stock ECU.

I looked around on here and couldn't find any info on anyone using pin 64. Has this been done or does anyone see an issue with this approach? Seems like a pretty simple way to add logging capability to the stock ECU.

Edit 1: So I should have done my HW a little better. The ECU pins I mention in the above link are WRONG for this. Those are the large pins, and pin 64 is one of the small pins. See this post to find the correct one:

https://www.evolutionm.net/forums/ec...ess-how-s.html

Trying to find somewhere to order the small pins from now...

WRC-LVR

iTrader: (1)

Pretty sound idea. Do it and report back. Note to other readers, this is for electrical pressure gauges only. could work with any thing that outputs 0-5 V or 0-4V though

blockade35

iTrader: (8)

Car is apart right now but needs to be alive by April for the first race. I just ordered the ECU pin so I guess I'll give it a shot and see how things go.

burgers22

Nice, subscribing for updates

merlin.oz

It should work ok.

blockade35

iTrader: (8)

Updated, looking for the correct ECU pins...

wip

This post is the motivation I needed to sort mine.

I installed the sensor/ECU pins years ago and added the Evoscan formulae but never got around to finishing the wiring off

FWIW, I also installed a couple of toggle switches on the back of the glovebox so I could try and utilise a couple of inputs per ADC:

Pin 64: EGT/Oil Temp
Pin 73: LC1
Pin 93: Oil Pressure/Ex Backpressure

It has been so long that I now need to go and read my notes as I can't even remember where I got to with it all

blockade35

iTrader: (8)

I wouldn't have thought to use 93. Is that sensor used anywhere by the ECU - i.e. does disconnecting it cause CELs.

blockade35

iTrader: (8)

Ok so been quiet for a while here, but the car is finally back together and I got a chance to update the tune today and see how this was working.

The good news is it seems to be logging just fine, which will be great to have for race day. The bad news is that the scaling is off by I want to say around 50%, so I have some work to do there still to figure out why. I am hoping that is the easy part though.

Once I have it all done and dialed in I'll put a full writeup on this mod here and on the upshiftracing.com website.

blockade35

iTrader: (8)

Better late than never, but I got this working properly. I found the transfer function for the AEM sensor on their website and scaled off of that rather than the 0-5v as listed in the instructions. The gauge basically goes from 0.5V to 4.5V max, so you have to adjust the transfer function in Evoscan to match.

For the 100PSI gauge, the function you want is .490*x-12.5 (tested verified in my car).

If you have the 150PSI gauge I believe the function you want it .735*x-18.75.

Short summary of the math here. since the gauge maxes out at 4.5V, 4.5V must equal the max pressure, so for the 100PSI gauge 4.5V = 100PSI. 4.5V on a 0 to 255 scale is 229.5. The gauge also starts 0.5V, so 0.5V = 0 PSI. This creates an offset function. 0.5V on the 0 to 255 scale is 25.5.

So your function must work such that when you input 229.5, you get 100PSI (or 150 is you are on that gauge), and when you input 25.5 you get 0. It's all linear in between, and the math is pretty easy from here.