Temprature sensor on Air Box..
10-20-2004, 01:26 AM
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Staging Lane
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Temprature sensor on Air Box.. Met a guy with an 00 SS and he said he got an adapter for it because it raises the Timing 2-4 degrees...?
Haven't found one from a performace shop.. Does anyone know what this is?
Thanks!
Haven't found one from a performace shop.. Does anyone know what this is?
Thanks!
10-20-2004, 02:14 AM
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The Intake Air Temperature (IAT) sensor is a thermistor, (a resistor that changes resistance with changes in temperature) mounted in the air cleaner
housing Of the intake system. Low intake air temperature produces high resistance in the sensor, approximately 101k ohms at -40°C, while high intake air temperature causes low sensor resistance, approximately 80 ohms at 130°C.
The PCM:
1. Supplies a 5 volt signal voltage to the sensor through a resistor in the PCM, and
2. Monitors the intake air temperature circuit voltage, which will change when connected to the intake air temperature sensor.
The circuit voltage will vary depending on the resistance of the IAT sensor. The voltage will be close to the 5 volt level when the sensor is cold, and will decrease as the sensor warms.
The IAT sensor signal voltage is used by the PCM to assist in calculating the fuel injector pulse width, idle speed, canister purge and electronic spark
timing.
Using a resistor in place of the IAT sensor will fool the ECM into thinking the air is colder or warmer than it is (it depends on how many ohms your resitor is).
Timing is just one of the things, I wouldn't short the IAT sensor if I were you.
In fact, on my car I moved the IAT sensor on the volant intake from the wall to the actual Y intake tube.
housing Of the intake system. Low intake air temperature produces high resistance in the sensor, approximately 101k ohms at -40°C, while high intake air temperature causes low sensor resistance, approximately 80 ohms at 130°C.
The PCM:
1. Supplies a 5 volt signal voltage to the sensor through a resistor in the PCM, and
2. Monitors the intake air temperature circuit voltage, which will change when connected to the intake air temperature sensor.
The circuit voltage will vary depending on the resistance of the IAT sensor. The voltage will be close to the 5 volt level when the sensor is cold, and will decrease as the sensor warms.
The IAT sensor signal voltage is used by the PCM to assist in calculating the fuel injector pulse width, idle speed, canister purge and electronic spark
timing.
Using a resistor in place of the IAT sensor will fool the ECM into thinking the air is colder or warmer than it is (it depends on how many ohms your resitor is).
Timing is just one of the things, I wouldn't short the IAT sensor if I were you.
In fact, on my car I moved the IAT sensor on the volant intake from the wall to the actual Y intake tube.
10-20-2004, 08:09 AM
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Putting the thermistor into the airstream is a good idea.
GM did it with the 85mm Delphi MAFs. If you leave it
remote it will have more heat pickup / soak and give
you reduced timing for a long while after startup. The
stock box has it in a reasonable place, my SLP Blackwing
was off in a corner and would take 5 minutes to come
back down to air temp after being hot-parked.
As to the original question, there are writeups on the
"Radio Shack resistor IAT" mod or some such naming,
those keywords would turn it up I'm sure.
I believe its usefulness may vary by year; on my '02 the
stock timing table has no advance for low IAT, only
retard for hot. So "tricking" it to think it's cold would do
nothing for me. Maybe earlier years are different. Of
course it costs 59 cents to try the "Radio Shack IAT"
resistor version of this and see if you're lucky.
GM did it with the 85mm Delphi MAFs. If you leave it
remote it will have more heat pickup / soak and give
you reduced timing for a long while after startup. The
stock box has it in a reasonable place, my SLP Blackwing
was off in a corner and would take 5 minutes to come
back down to air temp after being hot-parked.
As to the original question, there are writeups on the
"Radio Shack resistor IAT" mod or some such naming,
those keywords would turn it up I'm sure.
I believe its usefulness may vary by year; on my '02 the
stock timing table has no advance for low IAT, only
retard for hot. So "tricking" it to think it's cold would do
nothing for me. Maybe earlier years are different. Of
course it costs 59 cents to try the "Radio Shack IAT"
resistor version of this and see if you're lucky.
