If they're in Parallel then the POT will not give the same effect on all resistances..

I'm not pulling my o2 at all for many reasons, one of them being the fact that this is supposed to be on the fly.

With the pot (high value) in parallel, it decreases the overall resistance of the circuit. A 100k pot goes from 0-100k. This would be the perfectly simple way of accomplishing what you want.

At 100k, it wouldn't be affecting the IAT reading much, but as you drop the POT resistance, it does.

Ok i see what you're saying now. Basically make the resistance terribly high so nothing would go through there anyways.

You got it. The higher the better. A 1meg pot will still go to 0.
Do the math to see how much the high end of each pot will affect the circuit resistance. You don't want this to affect normal driving at max by very much.

What range would be best? I'm going to run 2 wires for this into the passenger compartment.

I don't like doing that math. I'm still in basic EET class.

My goof. I had the ratio on the temp/resistance backwards in my head.

When the IAT reads higher temps, the resistance is LOWER. In that case, you want to INCREASE the total resistance in the circuit.

-40°F (and Celisus coincidentally) is 100k ohms. That'* the coldest value listed. For comparison, 212°F is 177 ohms, and 59°F is 4450ohms.

Add a pot in series with the IAT. Not in parallel. If it'* 95°F outside, you are running at 1.8Kohms. By adding in about 2.6k, you can make it think it'* 59-60°.

Adding in a 5K pot, cranked all the way would be 41° indicated.

There are some unknowns here. How much colder do you need the IAT to read? A 2.5k or a 5k pot would certainly do the trick. On another note, you don't really need a pot, but rather just a rheostat, although a pot can be wired as a rheostat, and by picking which tap you want, you can have it dial either clockwise or counter-clockwise to achieve your results.

Oh yeah, all those ebay modules are inline resistors, more resistance = more power.

Ok a Rheostat.

41* of temperature change there? Hrm... Sounds close, I'm curious to see if anyone can log IAT temp/timing on a scantool. I think 5 degrees is all we would really need, and that'* pushing it, unless we'd like to use race gas.

Dame?

Jason, wire up two and send one to Dame to test with his Actron.

I LOVE his ideas...

With your L27 and scantool, you're the best candidate to characterize this. Compare your findings with Jason'* seat-of-the-pants dyno.

Although you'll find that this time of year it won't make much difference.