OK heres my question I just installed and relocated my MAT sensor from the plenum to the intake as directed. MY question is this I know the theory is that the MAT located in the plenum attains false readings via heat soak and the ECM receives erroneous readings. Well I took the iroc out and I could not really see too much of a difference. Is this because it will be more of an efect during hotter weather. I live in MASS. and the temp was about 41 degrees today.

 

Certainly. Cool weather would make a big difference in the temps within the plenum.

I would imagine it would be more affected when you shut off the car after it has warmed up, shut off for a few minutes then started up again. Kinda like the staging lanes when drag racing.

 

Massz, Is your car a MAF car?

 

Yes it is equipped with the MAF sensor and I also just placed a new upper intake also with SLP runners, 52mm TB, and ported plenum. I also port and matched all the gaskets so I figured on doing this mod anyways even though I also replaced the mat sensor under the plenum.

 

Relocating the sensor on a MAF car is not beneficial as it is on a S/D car. It will only alter the EGR enable temp by relocating it. The cooler the air is calculated, the later the EGR will activate. With a S/D car you can get the "real" incoming air temp. with the relocation. IMO,There is no performance gain though.

 

Brutal- the MAT sensor isn't used to alter timing or something else on on a MAF car? That's interesting, if true.

I have done MAT relocations on several TPI cars- MAF and SD. Can't say it ever made the car any faster, but it helped the car stay more "consistent" as temps rose. Like bracket racing, between rounds the engine would heat soak the MAT pretty bad (even icing down the top of the plenum) and I would notice the car would "fall off" quite dramatically- several tenths. Relocating the MAT helped quite a bit. Car would still fall off, but not as bad.

My foggy memory banks are telling me this was true of both kinds of TPI engines.

 

It's true. The MAT relocation kit is completely useless on a MAF car, the only thing it controls is the EGR. And it actually screws it up, not improve it. You would be better off stick a 4.7K resistor into the connector leads for the MAT sensor on a MAF car.

It is the MAF that determines ALL fueling adjustments based on the reading of the incoming air temp as it blows across the MF's sensor wire. Humidity, air density and air temp are all converted by the incoming reading across the MAF wire - the MAT is not used whatsover.

And spark is based only the "LV8 or load factor based primarily on your TPS", and the knock sensor.

Only SD TPI cars actually use the MAT sensor for fueling corrections (and EGR also). If you relocate the MAT sensor on a SD car, you MUST recalibrate the MAT tables in the SD car's eprom or the fueling will be incorrect. And there are no such tables in a MAF car's eprom.

 

BTW, 3rd Gen TBI cars MIGHT also use the MAT sensor (though I have not checked to verify). On certain year Truck TBI vehicles, they don't even have an MAT sensor.

 

They do, it is just a different part number.