festiva IAT Sensor location?

[festy90]

ive been trying to find my Intake Air Temperature Sensor for a few days now so i can check it but i can find it. the haynes manual i have is no help as usual. can anyone tell me where it is or post link that has a pic of it or a diagram i can see? and what wires are what on it? if it is a four wire one then it most likely has two signal wires and probly a power and ground but not sure.
the main reason i want to know is i bought a performance chip for it that has to be connected to the IAT sensor to work but i cant find the sensor to install it.

[yutz]

Iat

i dont know, but the haynes book that i have shows the picture and exact location.check book # 36030 haynes repair manual. has picture of aspire (red car ) on front cover. says 1988 thru 1997 all models. pages 6-12 6-13 IAT 1994 and later models. it says the IAT is located inside the air cleaner housing.looks like a two wire connector. hope this helps. joey g

[festy90]

yeah thats the one i have but the only wire on the air cleaner looks nothing like whats in the book

[festy90]

after rechecking and compairing what i have to the book i noticed the book says for 1994 and later models which does me no good since mine is a 90. that and they didnt have festivas past 93 or 94 cause they went to the aspire line. i still need to know if my festiva even has one of those sensors cause i can only find the MAF and airflow sensors which are also shown in the book

[SIBladerunner]

its part of the VAF, one of the wires, forgot which one, but it says on the wiring diagram

[CharlieZ]

Checking the 91 Electrical-Vacuum Troubleshooting Manual, I don't see an IAT sensor in the diagram. There is a Engine Coolant Temp sensor ECT. The IAT, to the best of my knowledge (other cars), is a vacuum device withing the air cleaner on carbureted engines.

The ECT connects to pin 20 on the ECM.

[jglutz]

^^It's in the book. It's internal to the VAF block as part of the resistor bank. The resistors measeure the vane position and the air temperature...the product of both is then combined with the barometric pressure sensor in the ECU to determine Mass Air Flow.

Unfortunately I've never seen a spec for testing the VAF for either voltage or resistance as a proprtion to vane position and air temp.

[FB71]

I think we're missing the major issue here. festy90 is trying to install one of those wonderful Ebay "Performance chips".

festy90, do yourself a favor, and just throw it away and chalk this up to a learning experience. It's a simple $0.25 resistor. The idea is to bias the IAT voltage high, so the ECM thinks the engine is colder than it really is. That will cause the ECM to add a little more fuel. Well, at least for the first few minutes. After the car runs for a bit, the ECM goes into closed-loop mode, and the O2 sensor will tell the ECM the mixture is too rich, and the ECM will lean out the mix to the proper ratio. The Festiva ECM isn't sophisticated enough to be fooled by the resistor for long. I know that sounds backwards, but the IAT circuit doesn't have that much effect because the ECM only uses the VAF/IAT voltage to "guess" at the proper fuel delivery value, then fine tunes it with O2 sensor.

[festy90]

well i appreciate the explanation but i have always been one to learn thru experiences and i know ill always wonder what if if i dont go ahead and give it a try. i have checked the haynes manual several times and yes it does talk of an IAT sensor being in the air cleaner box, but only on 94 and up models(aspires). my engine doesnt even have a box that looks like that on it. just the air filter box with the MAF sensor in it.
the package of the power module noted that it can be connected to the Engine Coolant Temp sensor if there isnt an IAT sensor which is supposed to be located on the top section of the intake manifold under the throttle controls but i havent been able to locate that either. little car + big hands = tough time lol

[FB71]

one correction, it might help you understand the system; The Festiva has a VAF, not MAF, big difference. MAF uses a hot and cold resistor wire Wheatstone Bridge type voltage divider. The VAF uses a flapper door connected to a potentiometer. VAFs are much less accurate at measuring airflow. In order to attempt to correct the airflow value for ambient temp, a thermistor is used in the VAF circuitry to directly modify the VAF output voltage. So, while the Festiva does have an IAT, it is actually incorporated into the VAF, and does not have an independant signal wire. There's basically nowhere for you to attach that "chip". The seller outright lied to you. I hope that helps.

The ECT sensor you're looking for can be seen on the bottom of the intake, from underneath the car. It has a green, two-pin connector. Be VERY cautious of adding resistance to the ECT circuit. A very low ECT signal can force the ECM to continuosly run in "choke" mod, which will quickly foul the sparkplugs and wash out the cylinder walls, causing cylinder damage.

[floydiancomplex]

The ECT is by the injector rail between cylinders 1 and 2. It has a green connector and
2 wires. One is signal and one is ground. It doesn't matter which one you hook it up to
because it won't work anyway and you wasted your money. - Chris

Or Fb71 is right and it might damage something.

[festy90]

yeah i found it and hooked it up. i did give the car a boost in power and acceleration but at the same time it was telling the car to dump so much fuel into the cylendars that it would load up if i tried to get on the gas hard. i took it off bout a week ago because it started flooding the engine on start up. if i had been driving the car for 15 min or more and shut it off then the first time i tried to start it up it would dump way too much gas in and flood the enging. it did it two days in a row and stranded me so i took it off. lesson learned. that type of chip does not work for my car

[festy90]

im only out $20 so it was an ok experiment. no harm done to the engine and it runs fine now that its disconnected

[Ogrestiva]

yeah i found it and hooked it up. i did give the car a boost in power and acceleration but at the same time it was telling the car to dump so much fuel into the cylendars that it would load up if i tried to get on the gas hard. i took it off bout a week ago because it started flooding the engine on start up. if i had been driving the car for 15 min or more and shut it off then the first time i tried to start it up it would dump way too much gas in and flood the enging. it did it two days in a row and stranded me so i took it off. lesson learned. that type of chip does not work for my car

Lesson learned...Listen to FB71!

[festy90]

yeah well i like to learn things on my own. that and just because something didnt work for one person doesnt always mean it will never work for anyone else.