Just wondering how much does the MAT actually control the fuel mixture, and also was wondering on a MAF car does it really matter that much to change it to the newer style LT1 MAT thats in the air cleaner?

 

From everything that the gurus can find so far, the MAT does not control fueling at all in MAF cars.

In SD it is used as part of the VE calcs

 

Then what does it control or do other than send the info to the computer?

 

Supposedly, on MAF cars, the sensor is downstream of the EGR outlet and tells the ECM if the EGR is operating or not by sensing a change in the intake air temp (hotter) when/if the EGR system operates as designed and intended.

 

Mass airflow sensors are the most accurate way to determine load on an engine due to air's elasticity when heated and cooled. The ECM uses this data along with the rpm to determine a fuel injection pulse width. The OXYGEN sensor is used as an auditor to trim the fuel ratio. Hope this helps.

 

We are talking MAT (Manifold Air Temperature) not MAF (Mass Airflow Sensor).

 

ok so then since I have the vette alum heads with no EGR passages the MAT is useless? other than to throw a code if it goes out?

 

AFAIK - that is correct
For MAF cars the MAT is only used to determine the temp at which the EGR can be used.

Tim

 

So relocating the MAT on my 88 mass air flow car did noting but
mess up EGR feedback that the ECM is looking for ?????

 

As far as we know, yes, a relocated MAT on a MAF car does nothing for you. So far noone has found any code that uses the MAT for fuel in the MAF bin, nor has anyone shown scantool data to suggest that a relocated MAT changes fueling.

SD definitely uses the MAT for fuel calculations, i was just reading the routines the other night...