I swapped my manifold this weekend for a Edelbrock performer TBI... After the swap was done I started it up and it runs ok, but after about 5 min I get a check engine light. I pulled the code, and its 25, manifold air temperature sensor. Correct me if Im wrong, but isnt that the sensor that was originally in my air filter? When I switched to an open element, I zip tied the sensor away from the engine. If this is the same sensor that would trip code 25, its possible the sensor may have fell down next to the header and is absorbing too much heat. I remember reading that the sensor can be swapped for a resistor, but i dont remember what resistance. If it can, anyone know?

 

the sensor in your air cleaner is the Incoming Air Temperature Sensor.

------------------
Flowmaster 80 series muffler
K&N Open Element cleaner
Ultimate TBI Mods Subframe Connectors
lead pedal foot . See my baby @
http://oursportscars.homestead.com/home.html

 

Ok, well, I was under the impression that it is the same sensor, since there dosent seem to be any other air temperature sensor on the manifold as far as I can see. Anyone??

 

Your MAT sensor is either faulty, or has been disconnected. It is normal for the SES light to come on with this fault after the engine has been running for one minute.
If you just finished doing a manifold swap, recheck the wires and sensor to make sure they are OK. Unless you are good with electrical components and soldering, I wouldn't bother with the resistor gimmick.....the results are not worth the effort.

------------------
92 Camaro RS, LO3, 5-spd, T-tops

Performance:
K&N Open Air Filter, Edelbrock performer TBI intake, Fastchip Prom, Timing +4 degrees, Centerforce clutch, Xact 8mm wires, SLP 1 3/4" Headers (coated), Flowmaster Catback Exhaust, Z28 Grille w/aftmkt fog lamps, MacEwen white-face guages
Electronics:
Alpine 8030 Alarm System, Valentine One Radar Detector (How did I ever drive without one?), Pioneer DEH 7450 Head Unit w/6-pack CD changer, Pioneer DEQ 7600 Sound Processor, 2 Kenwood KAC-846 Amps powering 2 12" Pro Red subs, 2 Pioneer 6x9 and 2 MTX 4x6 speakers.
NEXT UP: TBI mods, 3.42 gears w/Torsen posi

 

Also, relocate the sensor to a cooler part of the engine bay (definetly not near headers) which may be the reason for your fault, or may have damaged the sensor

 

Ok, but just to clarify, this is the same sensor, correct? The "IAT" and the "MAT" (Incoming air temperature and manifold air temperature) is actually the same sensor, which was originally in the stock air cleaner...?

 

BOTH are located inside the stock air cleaner assembly. The IAT connects to the flap over the heat riser tube. It bends when it gets hot, plugging the vacuum signal which closes the flap on the heat riser. On a stock air cleaner assembly, the flap is open in order to heat the car faster. the IAT is NOT connected to the ECM.

The MAT IS connected to the ECM and feeds the computer a signal that is used toward adjusting fuel flow.

The IAT is actually inside the air cleaner assembly while the MAT plugs into the base of the assy.

Hope this clears things up