Iat Spark

[Chris@HPTuners]

there is no MAT sensor, MAT is calculated based on a blend of IAT (or IAT2 if fitted) and coolant temp based on airflow etc.

[Blades]

So could we make our own IAT2 using a custom pid/equation?

[Chris@HPTuners]

So could we make our own IAT2 using a custom pid/equation?

no

[BMBSALES]

The Manifold Air Temp PID will be close to IAT2 at higher engine speeds so you could use that as a guide. Or you can just look at the IAT Spark PID and estimate IAT2 by the amount of retard you are getting.

it does seem to coincide but why only at higher engine speeds, because of larger fluctuation scale? it looks like it will swing almost 100* wot.

[Chris@HPTuners]

take a look at the tables that control this, the higher airflow values have less weighting towards ECT and the filter values make the filtering faster at higher airflows. Engine -> Airflow -> Cylinder Charge Temperature

[Blades]

Was this added in the latest beta? 2.23.3567.27058

[BMBSALES]

THANKS CHRIS! I'm about to give it a try.

[BMBSALES]

chris if you would take a look at this log...something still doesn't jive with IAT2 pid. it seems that if you use standard iat table and mult, you come up with the following let's say on frame 334 and inter between cells:

going by iat2... -1.5 *.2 = -.3
going by mat... -5 *.71 = -3.6 which is exactly what iat advance pid said that it pulled on that frame.

it would seem that it's the mat that uses these tables on this s/c one?

[Chris@HPTuners]

chris if you would take a look at this log...something still doesn't jive with IAT2 pid. it seems that if you use standard iat table and mult, you come up with the following let's say on frame 334 and inter between cells:

going by iat2... -1.5 *.2 = -.3
going by mat... -5 *.71 = -3.6 which is exactly what iat advance pid said that it pulled on that frame.

it would seem that it's the mat that uses these tables on this s/c one?

ok there is some hidden logic here you cannot see, the IAT2 PID displays the raw IAT2 sensor reading. The IAT Spark table uses a prediction from the IAT2 reading that is meant to compensate for the slow moving IAT2 sensor. To predict IAT2 temperatures faster than the IAT2 sensor can actually measure them.

Now for the happy concidence

The MAT value is calculated from this predicted IAT2 value (using the usual Bias and Filter tables) and for your application the bias tables are all 0. Meaning MAT = Predicted IAT2.

So yes you are correct, the MAT value can be used in your case becuase it is exactly equal to the predicted IAT2 value.

For naturally aspirated applications with one IAT sensor this compensation is not done and the IAT Spark table uses the meaured IAT value.

(phew!!)

Chris...