Quote:
And I assume this parallel rheostat would go to ground somewhere between the ECU and the series trim pot? Doing so would make the lean adjustment over ride the enrichment adjustment.
Now, on to the ECT trim. Would I use the same size pot for this? And is it safe to assume that increasing the resistance in a series set up would show the ECU a cooler temp?
Thanks again for your help here.
Sam
With the additional pot to lean the IAT (simulate higher intake air temp) you will need to place one lead to ground and the other to the sensor wire, ahead of your other pot, so that it doesn't have that bias in it. Nothing bad would happen if you did, but you may get confusing results.Now, on to the ECT trim. Would I use the same size pot for this? And is it safe to assume that increasing the resistance in a series set up would show the ECU a cooler temp?
Thanks again for your help here.
Sam
The impedance of this additional pot will have to be quite high, because you will want to be able to turn it 'off' so it's not influencing the other pot/sensor combo. 'Off' means set to it's highest resistance since there isn't really an off. Looking at the table for the GM sensors, 25K ohms = 0 degrees F. Assuming you were above 0, a 25k pot would essentially be off since it would be higher resistance than your actual temperature sensor, so the current would flow through the sensor, not the pot. With a 25K pot wired this way, your IAT would never indicate lower than 0 degrees. BTW, -40F is 100,700 Ohms.
Handy reference table:
I think you could easily get away with a 10k to 20k pot for that depending on how cold you get. I imagine underhood air does not stay at zero for long.
This is how it would work - as you turn the knob to lower the resistance, at a certain point current will stop flowing through the sensor to ground, and start flowing through your pot to ground. You have the ability then to reduce the resistance to 0 as you continue turning the pot, as it will eventually go to no resistance at all. That would simulate a very high air temperature, over 200 degrees. I'm not sure how high a temperature MS looks at but that should be high enough for your purposes.
Then, for the second part of your question, a 5k pot wired in series with your CLT sensor ought to do the trick. Looking at the table, it can fool the MS into thinking the water temp is about 65F or so at max which should be plenty cool for a good WUE shot.
Here is an extremely crude Paint drawing of the setup:
You will be like the Wizard of Oz behind the curtain, turning all these knobs
Somebody smarter than me could figure a way to richen/lean with one knob. I'm looking into it...
