using jimstim to simiulate: 12v MAF, O2 heater, EGT probe?

[hassmaschine]

I'm working on a project with a factory ECU. I need to simulate as many (or all) inputs as possible to get good data out (I'd like to map out the entire spark table, for example).

I'm pretty sure I can do the MAF maybe using one of the existing pots, but has anyone tried to do it? I tried connecting the signal input from the spare ADC, but that won't work as the ECU needs the current load. could I run a jumper to 12v from somewhere to the spare ADC pot?

O2 heater - how do O2 sims work? it must be some sort of resistor from 12v? the narrowband signal input is obvious, but the heater circuit doesn't work with a floating input. It also looks for a short to ground and a short to 12v, which forces it into open loop (even if the narrowband input is valid).

EGT - I believe the stock ECU has the signal amp hardware built in, so I just need some sort of millivolt input. Suggestions?

RPM, temps, etc were all easy and are working already. I've already got some data but I need to be able to input load at least. I have two stims to work with so I have plenty of options..

[racingmini_mtl]

The first thing you have to be careful about is that the JimStim does not have a 5V supply on-board but uses the ECU as the supply. So you need to connect a 5V source from the ECU to the JimStim (you can use the screw terminal at 5V position). If you don't have a specific 5V output on the ECU, the TPS usually has a 5V source connected to it. If there is an external MAP sensor, it will also have a 5V supply.

If the MAF is a type that outputs a 0-5V signal then you simply connect the spare pot to your ECU. Do NOT connect 12V to it. If the MAF is a frequency output type then you'll have to find some other way to simulate it.

The wideband O2 signal is a 0-5V signal. It does not simulate the sensor but an external WBO2 controller. So there is no heater simulation. If you have an internal WBO2 controller, you'll have to use something other than the JimStim to simulate it.

And there is nothing obvious that you can use on the JimStim to simulate an EGT probe. I guess you could use a voltage divider at the output of the spare pot but you'll have to find which resistor values to use to get the correct output range for your application.

Jean

[hassmaschine]

The first thing you have to be careful about is that the JimStim does not have a 5V supply on-board but uses the ECU as the supply. So you need to connect a 5V source from the ECU to the JimStim (you can use the screw terminal at 5V position). If you don't have a specific 5V output on the ECU, the TPS usually has a 5V source connected to it. If there is an external MAP sensor, it will also have a 5V supply.

thanks.. that must be why the 5v ADC signals weren't working! I never even thought of that.

If the MAF is a type that outputs a 0-5V signal then you simply connect the spare pot to your ECU. Do NOT connect 12V to it. If the MAF is a frequency output type then you'll have to find some other way to simulate it.

I thought it was a 12v signal (based on current output to keep the elemet at temp), but I need to do more research. perhaps it's a 12v supply but 5v signal. I'll hook 5v to the board and try again first.

The wideband O2 signal is a 0-5V signal. It does not simulate the sensor but an external WBO2 controller. So there is no heater simulation. If you have an internal WBO2 controller, you'll have to use something other than the JimStim to simulate it.

it's actually a narrowband input. I thought I could remove the "WB" jumper and it would output a 0.0-0.1v signal? I'm going to try to run 12v to the heater control with a big resistor and see if that works.

And there is nothing obvious that you can use on the JimStim to simulate an EGT probe. I guess you could use a voltage divider at the output of the spare pot but you'll have to find which resistor values to use to get the correct output range for your application.

Jean

I think I can figure out how to build the required circuit, but I was looking for more along the lines of what voltage range a typical EGT sensor puts out.

thanks for all the help!

[hassmaschine]

Connected the 5v output from the ECU (used specifically for the MAF) to the stim - the MAF works as expected now! I feel dumb.. :p