MAFs

[Axel Rietschin]

From: "Bruce Plecan" <nacelp at bright.net>

> How about the shear fact that if the IAT compensation is internal to the
> MAF, then the metering allows for heat saturation of the I/C.

What comes in, comes out, no? Less temp, more density, less speed but same
amount of _air_, or did I miss something?

>  For doing
> things as correct as possible makes the tuning all the easier.   this way
> just a MAT timing table would allow for perfect tuning, or close to it.
> All the IAT and MAT sesnors I've tested are rather slow to respond.

Certainly fast enough to cope with for atmosphere temp change from what I
know, but now, for post turbo air temp change? IC will smooth things out but
to what extent? T63 constant of automotive air temp sensors I know of (Bosch
& Marelli) is in the 20s range, meaning it takes about a full minute to get
an accurate reading, which rule out most 'real-time' control strategies
based on that value.

> This
> eliminates that, at east for thair sensing.  Now an MAT can be used for
> timing control.  Still would be slow, but beats having errors in both
timing
> and fuel.

Yes, probably, but a minute late is really late as far as timing is
concerned :) Anyway, if the air charge temp raises quickly and the sensor
don't see it fast enough, the engine will run a bit richer than necessary,
which is on the safe side, so no big deal unless you are super-concerned
with fuel economy.

--Axel


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