MAF vs MAP

[atsakiri at ford.com]

> atsakiri at ford.com Wrote:
> | 
> | 
> | > MAF sensors can handle all the transients you can throw at them 
> | > provided they're set up properly, ie, they're sampled correctly and 
> | > you have some form of manifold filling compensation.  I suspect that 
> | > the additional MAP sensor is for added functionality, perhaps EGR 
> | > control or maybe something else.

I responded to this, but I didn't write it.  (Technicality.)

 
> Seems like the MAP sensor could be used to measure the transients in the 
> manifold.  Then maybe you wouldn't need to use throttle delta to calculate 
> the acceleration enrichment.

Yes, one would think that.  I'm sure it can, but I've never come
across a specific, complete plan detailing how to do it.  That's
not to say one doesn't exist.  Decisions need to be made regarding
under what condition to use which sensor, how to switch modes, 
etc.  It gets cumbersome (computationally, in the production
world) quickly.

As for acceleration enrichment, we've entered a new arena.  Now
we're discussing A/F ratio control, not measurement of inducted 
air.  If the approach is to add additional fuel, without trying
to measure air then calculate the amount of fuel (based on 
measured air and desired A/F ratio), then why add a MAP sensor?
The throttle position sensor is already there.  Am I missing a
benefit of MAP-based enrichment over throttle-based enrichment?


Anthony Tsakiris


A/F = air-fuel
MAP = manifold absolute pressure  (Should I still be adding these
                                   definitions.  I recall a past
                                   discussion.)
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The opinions expressed are my own and not necessarily those of my employer.