MAF vs MAP

[SRavet at bangate.compaq.com]

atsakiri at ford.com Wrote:
| I responded to this, but I didn't write it.  (Technicality.)

oops

| 
|  
|>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.

I'm not talking about switching modes, I'm talking about using both sensors 
as inputs to a control equation.  Throttle openings and closings can cause 
transients in the manifold/plenum that the MAF sensor won't see, right?  
There was a discussion a long time ago about equations to model these 
transients in order to correct the MAF measurement.  It seems like using a 
MAP sensor to measure transients would be easier than constructing a 
mathematical model of the intake.  Isn't the throttle based enrichment 
algorithm a simple way of approximating this transient condition?

| 
| 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?

No, I am probably missing it.  You are right, the throttle sensor is there, 
might as well use it.  I was curious about a MAP sensor in this application

| A/F = air-fuel
| MAP = manifold absolute pressure  (Should I still be adding these
|                                    definitions.  I recall a past
|                                    discussion.)

might as well....  I remember being pretty lost right after I first 
subscribed.

Steve Ravet
sravet at bangate.compaq.com
Baby you're a genius when it comes to cooking up some chili sauce...