To control and force the PCM to have a much cooler Intake Air Temp (IAT) the design I have designed allows you to dial in what temp is being told to the PCM.
It's lying as to real temp but PCM does not know that and adjusts fuel trim and timing for bogus temp number.
By setting a resistance value, converts to a temp number and that is feed to the PCM as being the real airtemps.
This allows you to tune the fuel trims and engine timing.
The 10K pot mainly is used between 4.5 and 5K ohms which equal 45 to 78 degrees.
Thus middle of dial would be 5K ohm and 78 degrees.
Each 100 ohms from 4.5K equals 7 degrees.
If a pot is not wanted, replace it with a set known resistance value but be aware you then cannot adjust on the fly and have to manully change resistor value.
With the circuit below, when switch is turned off the stock IAT sensor is functional.
When switch on, the the pot is functional.
I have built and tested this IATuner and it works very well, in fact WOT timing gained 3 degrees by using this circuit
[ 07-11-2001: Message edited by: teamzr1 ]