Well I gone and added the 4th switch to my setup. It didn't take long at all to daisy chain in the 3rd switch to the IAT and make it functional. No longer have to play with rheostat's or stuffing the IAT plug with wires. I'll get my video up here really quick.

Here is the video...

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It. Was 79 here today Looks good mike. What are all the switches for again ?

That's slick!! What's that on your oil fill cap?

It. Was 79 here today Looks good mike. What are all the switches for again ?

I guess you didn't watch the video. From left to right. 1. ECT fooler set engine temp to 123*F 2. IAT master switch to fool or use the IAT sensor 3. MPG fooler set IAT to 143*F to simulate summer conditions. 4. 3/6 Cyl high idle mode select. So Now I can start, stop and control high idle functions anytime. Now I can forcibly control IAT for aiding in economy of the engine.

That's slick!! What's that on your oil fill cap?

Frantz Filter Bypass OIl Filter return. http://www.wefilterit.com/ Really good product made right here in Nampa, Idaho!

So do you need four switches or can you just get away with 3 and by pass the ecm or would you loose the ability to fource high idle when the truck is warm?

1. ECT fooler this is to hold the ECT (Engine Coolant Temperature) low so high idle will remain set all the time. Once ECT hits 170*F then high idle is canceled.

2. This switch either select the IAT fooler or IAT (Intake Air Temperature) Sensor.

3. This switch selects 143*F IAT Temperature for MPG fooling.

4. This switch selects 13*F (3 cyl) or 26*F (6 Cyl) for high idle mode.

I can ditich the #2 switch and then lose the MPG fooler the rest are part of the high idle system.

Since the high idle is about fooling for colder IAT temperatures and MPG fooler is about fooling for hotter IAT temperature it makes sense to combine the extra switch in the IAT circuit so you can have both worlds but build it with safety lock outs so you can't select both at once.

Oh a road report from yesterday...

Made a typical round trip to McCall, ID 70 mile round trip for groceries. Return home at 20.9 MPG. Winter front used. This also includes climbing 7% grade too.

Weather: Clear 35*F

Actual IAT: ~85*F

Forced IAT: 143*F

It's nice now because I can flip the switch off and check IAT temps see actual and then set the fooler again.

So we're still using the 2.2K ohm, 1/2 watt resistor IAC fooler, right?