Originally Posted by Yanksmell
Simple! I was an engineer for Ford for years, I know this stuff.
The IAT sensor is measuring the temperature of the incoming air. The air temperature is indicative of the density of the air. Cold air vers hot air effects the combustion as octane (slower flame propagation) the same effect as water injection or alcohol (1/2 the BTU’s of energy as gas).
Placing a resistor in the IAT circuit reduces the IAT constant in the fuel/air algorithm (14.1 to 1) allowing the ECM to advance the spark allowing for higher performance and better fuel mileage until the ECM detects knock from the knock sensor. At this point, the ECM is advancing the spark as far as possible until the knock sensor input signals knock and the ECM than backs off the spark advance. The engine is now under the control of the knock sensor.
This concept forces the ECM to evaluate coolant temperature and knock more prominently than air temperature. This is engine design 101. Remember advancing the spark of a SB Chevy until the engine knocked… same thing here only that the ECM keeps pre-detonation under control at all times.
No ill comes of this due to the fact the ECM is always there to retard the spark if a knock occurs. If you use high-octane fuel, the ECM will give even more advance, longer push, more power, better fuel utilization.
The effect of injecting water into a carbureted engine produced more HP because the water would capture the heat and expand (like a steam engine (10 to 1) and the water would cool the combustion chamber causing a slower flame propagation resulting in a longer push on the piston. However, water injection simply pisses with fuel injection so say good-by to cheap octane boost ideas. This is what alcohol does with ˝ the BTU’s of energy; less energy but longer push.
Keep in mind, no knock is the secret of the HEMI head and all its power. Point of fact; the HEMI engine was designed after an air compressor at the Chrysler Engine Plant in Detroit.
Prior to making statement like the one you have, study up before name-calling. As far as HP increase; you bet but only what the engine can produce at max advance. 20HP---30HP---40HP… only a dyno knows but there is an increase in fuel mileage and power.
Why not done at the factory; a catalytic converter can overheat if pulling a heavy load with a mod like this but… seen a trailer hitch on a ZH lately.
Straight POOP boys and girls. I knew this crap when I was 14.
I would have just said it doesn't work.. lol. I wouldn't trust anything that tricks sensors into reading different values.