Re: Editing proms (editorial)

[Ludis Langens <ludis@cruzers.com>]

Kevin R wrote:
> 
> Keep in mind that the AFR settings and such aren't real numbers. It would be
> nice if they are close, but the ECM uses calculations based on what it's
> told are the current injector size/ motor size etc. Since there is more to
> accurately gauging AFR than these variables, (and this assumes the prom IS
> set for YOUR injector and engine size) the WOT AFR setting much like the VE
> table numbers shouldn't be thought of in terms of actual AFR or VE.

To an extent, the AFR numbers have to be real.  Part of the closed loop
logic checks for a commanded AFR of 14.6:1, perhaps 14.7:1 in a few
bins.  At that point it'll use the O2 sensor to learn the fuel
adjustment so that it is actually running the engine at 14.6***:1.  If
some input to the ECM then suddenly changes causing PE mode with an AFR
of 12.5:1, the engine will be switched to running at 12.5:1.  Once the
engine parameters go beyond the learned range, then the AFR value can be
wrong.

Of course, if you are running the engine on some mystery fuel where
stoich is 13:1, then the ECM's AFR numbers will be all wrong.

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/

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