Sensor Questions?

[SRavet at bangate.compaq.com]

FIScot at aol.com Wrote:

|  >| Is this assumption correct, or have I credited the engine computer
|  >| with too much "intelligence"??
|  >| John
| 
|  >  John, you are correct, my description above was a little simplistic.
|  >  As long as the ECM is in closed loop, it will adapt (within the block
|  >  learn limits).  If you aren't closed loop, though, pre-programmed
|  >  values are used which will result in a lean condition.
|  >  Steve Ravet
| 
|     In the GM ECM's, whether you are in CL or not, the ECM is running
|     through the same 'preprogrammed' code.  Closed loop adds the ability
|     for the BLM to learn.  If not in closed loop, the BLM is still used,
|     and if not altered by a complete power off, will still correct the 
fuel
|     mixture from what it has learned.
| 
|     Part of the equation is:
| 
|     Fuel = Integrator * BLM * (rest of fuel calculation)
| 
|     In open loop, the integrator is set to neutral.  The BLMs are 
whatever
|     has been learned, so the fuel correction still goes on.  One caveat 
is
|     that some ECMs will check (and reset) the BLMs at ignition power on 
for
|     a tighter limit than is allowed during normal operation.  The same
|     things happen when in PE, i.e., the integrator goes neutral, and the
|     BLM is whatever has been learned.
| 
|     The only thing that closed loop adds is the ability to learn, and
|     the integrator (with help) keeps the fuel about 14.7 AFR.
| 
|     Scot Sealander   FIScot at aol.com

Interesting, Scot.  It doesn't seem that there is really a need for a MAF, 
then.  Is MAF just an aid to enable the CPU to learn better?  Or is there a 
MAF term in the fuel equation?

--steve

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