I found a bad connector harness to a sensor that is located on the passenger side between the two rear spark plugs. anyone know what this part is so I can find a new plug for it? also, whats the name of that sensor thats underneath the plenum towards the back, right between the EGR and the fuel regulator? I'm still learning about these TPIs and I have lost my manual. thanks for any help.

 

sounds like you are describing the aux fan switch and if the other sensor you are talking about is actually screwed into the bottom of the plenium the IAT sensor

 

this fan switch, with it not working properly, can the car overheat? cuz ive had overheating problems. and just curious what IAT stands for.

 

The sensor under the plenum sounds like the MAT (Manifold Air Temperature) sensor to me. I just replaced mine.

 

The sensor on the head between the spark plugs id a temp sensor. It goes to the ecm and is for fan control and maybe be used by the ecm for closed loop operation. Yes you will have overheating bc the fans will not function properly. with 80schild the other sensor is the MAT sensor

 

thanks guys, that should help me quite a bit.

 

By the way you can get new connectors from EFI Connections click the link on the boards home page. I have used them quite a few times for my TPI swap bc all the connectors to the bottom of the engine and tranny were cut off the harness I got when I bought my setup.

 

The aux fan switch controls the function of the secondary fan, and as improperly stated above DOES NOT go the the ecm. The primary fan is controlled by the ecm, the sending unit for that on a tpi engine is in the front of the intake manilfold. If your engine is seeing high temps which cannont be controlled by the primary fan the secondary fan will kick in (assuming your fan switch is good), it also comes on when the a/c is commanded on. The sensor in the bottom of your plenium as I stated before is your IAT (intake air temperature sensor) which measures the temperature of the incoming air. On most cars they are located farther downstream in the intake tube itself, on our cars they are for some reason located in the intake plenium, and they are basically the same kind of sensor as a coolant temp sensor rather than a traditional IAT, some people have converted over to external IAT's like the ones used on v6 cars and have relocated the to the intake tube, there's a thread floating around here about that.

 

IAT/MAT = same thing. I think the term "MAT" is used more commonly though.

 

possibly by people who don't know the correct term.