Air charge temperature sensor

[SpencersGreenTurd]

Ok...still new to this forum thing but I had an idea about the warm air intake. Maybe it's been talked about, Ikd.... Why not run cold air (more dense) into the intake and just move the air charge temperture sensor near the exaust manifold? Has someone tried this? Should it? Could it?

[CigaR007]

Most IAT (Intake Air Temperature) sensors are built-in the MAF (Mass Air Flow) sensor nowadays. Physically moving the IAT sensor is too much of hassle, imo. Varying the resistor value of the IAT sensor should, in theory, trick the ECU; making it a much more sensible approach.

Concerning the CAI (denser air) in conjunction with a higher reported IAT is definitely an interesting approach. That being said, I believe other parameters are also required to determine the exact fuel quantity to be injected. Intake temperature is not the only variable to consider.

Perhaps a test is in order !

[SpencersGreenTurd]

Not sure what u mean by " Varyfing the resistor value" but my sensor is not in the map. And I think I ll will test it... Not sure how yet. Still a new idea to me. I ll have to mill it over and maybe get some more input.

[drmiller100]

Trying to fool your temperature sensor won't work if you have an 02 sensor. The computer reads the 02 sensor and adjusts the fuel trim to maximize fuel efficiency.

The air temp sensor , MAP or MAF, coolant temp, Throttle Postiion Sensor (TPS) are used to take best guess to get the car running in the morning.

As soon as the 02 sensor warms up and gets going, the computer trims out the mixture to make the exhaust "correct".

For faster warm up, you can use warm air off the exhaust, but that is about all you can do.

[SpencersGreenTurd]

What about the thread I read that says if ur coolant temp sensor is bad it will tell the computer it's still cold?

[mwebb]

air temp sensor is zero to 5 volts
1 pin is ground and must be within
50mv of battery ground / negative
as measured from battery negative to sensor ground .

the other pin if fed 5 volts and the is a variable resistor that changes value with temperature
it has a negative temperature coefficient
high resistance cold , low resistance hot , the resistance is
irrelevant
the voltage is not , the voltage on the signal side will be close to 5 volts when cold and around 2.5 volts at 70f and about .5 volts at 210f
values are approximate and will vary

the 02 sensor will keep fuel trim at 14.7 to 1
no matter the value of the air temp senor , BUT
ignition timing will be retarded for high air temperatures and allowed to be
more advanced with colder temperatures

values were determined by the engineers that programmed the
system

which is why
under reporting MAF / MAP / IAT sensor can improve fuel economy ,
not by changing fuel trim
but
by changing the ignition timing advance map ... having said that

ignition timing map and MAP (manifold absolute pressure) sensor
are not the same thing although the MAP sensor's input does change the ignition timing map .

do not frak with the ignition timing advance map if you do not know what you are doing .... peak combustion pressure is partially controlled by
base ignition timing and the ignition advance map ,IF ignition happens too soon
peak combustion pressure will also happen too soon
which will destroy your engine

peak combustion pressure is controlled by the ECM to occur at
14 degrees ATDC except at idle and DFCO
tamper with it at your own peril

[SpencersGreenTurd]

Well... It looks like this stuff is still over my head. It looks like what ur telling me is I want the air sensor to read cooler so the timing is advanced? What about the coolant sensor? How does that play in all this?

[greenkz]

ive been using a fixed value resistor ( 203*) instead of the iat sensor for about 8 months with no ill effects. im currently running it at 248* for this tankful to see what i get.

[mwebb]

Originally Posted by greenkz

ive been using a fixed value resistor ( 203*) instead of the iat sensor for about 8 months with no ill effects. im currently running it at 248* for this tankful to see what i get.

no ill effects ?
you mean except for the 27.22 mpg on a 2000 saturn sl1 of course .

the problem with this line of thinking is the first hint of an ill effect caused by tampering with the ignition timing map is a burned valve causing misfire on the offending cylinder -

the ECM does not see resistance , it sees voltage , a slight increase in voltage drop on the ground side will allow the IAT to report a slightly skewed colder temp while maintaining the ability of the IAT to influence the ECM according to air temperature ,
a much more desirable way to tamper IF YOU MUST Tamper with that which you have no knowledge of .

[SpencersGreenTurd]

It sound to me that (from what little I know) this is a poor design in fuel delivery. I think I ll just go back to using a carb untill they come out with something better than this poor excuse of a more fuel effecant way to deliver fuel. How may people out the r driving with a bad o2 sensor? I just changed my first one ever yesterday. Never knew that was the reason for bad mpg. Thanks for the help though, I think