: Where is my IAT Sensor located? 99 sts



phosphene
12-13-07, 04:34 PM
Where is my IAT Sensor located on my 99 STS?

I bought a mod chip. The installation instructions tell me to splice it in with the Intake Air Temperature Sensor. Where is this sensor located on my northstar engine?

My Chilton manual isn't clear. Is the IAT sensor the one in the throttlebody or in the intake tube thingamajigger?

pics please?

cvpiftw
12-13-07, 04:45 PM
the IAT is before the MAF in the intake


Id look in the airbox.

Submariner409
12-13-07, 05:26 PM
Wrong. The IAT is the small black thermistor located at the outer edge of the MAF bore just inside the 5-pin connector. 2 of the pins are for IAT, and the other 3 are: ignition 1 voltage, frequency, and ground.

If you're going to mess with the MAF, be very careful not to disturb any of the flow sensor resistors across the wire bridges. Replace it in the proper orientation in order to maintain proper flow signal.

^^^^ Search MAF and similar. Lots of info.

You appear ready to open a can of worms which may cost you an engine. There are no mods or chips for late N*'s. Your "mod" sounds like a supplementary resistor or circuit which will fool the IAT signal toward hot or cold, thus changing the fuel delivery and rate. Before you attempt to modify an engine for which there are literally NO meaningful mods save a decent CAT-back exhaust, search these threads and see what you're up against, and save a bundle of money in the process.

Submariner409
12-13-07, 05:47 PM
This is a comparison of an OEM and JET aftermarket MAF. I did extensive objective testing of the aftermarket unit and found no performance gain and a loss of .2 mpg gas mileage. The OEM unit is back in after 6 weeks and 1,450 miles.

The IAT sensor is the little black teardrop at 1 o'clock in the bore.

Trust me: the honeycomb flow straightener is there for a purpose and offers no significant restriction to airflow.

Click on the picture and scroll in....................

Ranger
12-13-07, 11:59 PM
Sub, if I remember correctly from my daughters '99, the IAT sensor is in the intake duct.


I bought a mod chip. The installation instructions tell me to splice it in with the Intake Air Temperature Sensor. Where is this sensor located on my northstar engine?
Do a search before you install this thing. You'll probably find that it does more harm than good.


My Chilton manual isn't clear.
Dump the Chiltons and get a FSM by Helm Inc.

Submariner409
12-14-07, 08:25 AM
Phosphene......OOOPs! Sorry......yet another '99/'00 change.

Saving up all the different changes, the '00-'03 series is quite a different car.

phosphene
12-14-07, 09:20 PM
the chip... "Unit adjusts pertinent air/fuel levels based on stock readings from the vehicles IAT signal and relays the new adjusted readings to ECU resulting in the performance enhancement."

Ranger
12-14-07, 10:14 PM
I think that all it is doing is lying to the PCM about the IAT. It fools the PCM into believing that the intake air is colder than it is, thus a richer mixture. These engines are highly sophisticated. They have multiple sensors that control everything. They were designed by highly educated and experienced engineers. Mess with one sensor and you throw everything else off. In reality, you are trying to reengineer some pretty sophisticated stuff. I still think you'll either see no proveable performance increase and/or will see other unwanted charactaristics, like fouled plugs, decreased fuel mileage, emission testing failures (if required) and maybe even an SES light and some DTC's. Let us know how it goes.

Submariner409
12-14-07, 10:22 PM
FWIW, this sounds like Japlish to me. Why isn't your present OEM setup programmed for the best performance/driveability already?

IAT sensor location be damned, TANSTAAFL (There Ain't No Such Thing As A Free Lunch).

Back to my slightly skewed post on IAT sensor location ^^^^....this thing alters fuel/air ratio in order to accomplish what, where, and when ?

Put the thing in. Drive it a while, and come back here with an honest opinion. Nobody in here is ashamed to eat their words for lunch. Learn by doing.

Sorry for the typeover, Ranger.....You're quicker than my hunt & peck......

phosphene
12-15-07, 05:36 PM
So, is the IAT sensor in the MAF, the intake duct, or the throttle body? lol

yes, of course i'm skeptical about this $30 "performance chip" That is why I am here. Also why it is not installed yet.

Ranger
12-15-07, 05:45 PM
The IAT sensor seems to have migrated closer to the TB over the years. I am pretty sure the '99 is in the intake duct between the air filter box and the TB.