HOWTO: Relocate Your IAT Sensor For Better Performance
Written by Wild Weasel
The IAT (Intake Air Temperature) Sensor is there to tell the car's computer
the temperature of the incoming air. It requires this to compute the correct
amount of fuel to add to the mix to give you an efficient fuel/air mixture to
run the engine.
The idea behind this mod is that if the computer thinks there is cooler and thus
denser air coming in it will add more fuel and the result will be more power. This,
however, is only a part of the whole picture and this page is written to debunk the
myths and warn people from doing mods they don't fully understand.
Note that this mod is very similar to those eBay "chip" scams that are always
popping up. The supposed "chip" will invariably turn out to be nothing more than
a resister which modifies the signal coming from the IAT sensor, sending a result
that tells engine that the incoming air is cooler and thus denser than it actually is.
The modification itself is very simple. You remove the IAT Sensor from the intake
tubing and plug the hole left behind. You then extend the wires to place it at the
front of the car in a direct airflow path.
The result, however, can be much more than you bargained for. What people fail to
mention when this comes up is that there are good reasons for the car to know the
actual temperature of the incoming air and that it doesn't just make arbitrary
decisions based on this information. The computer constantly adjusts the mixture
to keep it as close as possible to stoich (which is proper) and give you the best
possible combination of power and fuel efficiency.
If you're thinking then that doing this mod will give you more power at the expense
of some fuel efficiency, you're only partially right. While this will tend to
yield a small horsepower increase in the short term, and perhaps even the long term
as the carbon build-up increases the compression, over time it will ultimately lead
to expensive repairs and lowered overall performance. With the computer unaware of
the actual air temperature and thinking it's much colder than it really is, the
engine will be running almost constantly rich. The result with be much reduced gas
mileage and a build-up of carbon deposits from unburnt fuel which can foul spark
plugs and destroy the catalytic converter.
The trivial gains from this are in no way worth the troubles that can be caused.
You're better off spending a few dollars on a real mod and sleeping better knowing
you're not destroying your car.