In the detonation/pre-ignition article, it states,

"But under sustained load, at about 20 seconds, that air fuel ratio is richened up by the PCM to about 10:1. That is done to keep the spark plugs cool, as well as the piston crowns cool."

Obviously nobody wants piston melt-age... I'm curious about implementing something like this in my ECM/code.

In other words, the longer you're in PE, the lower the AFR goes. After 20 seconds, it hits bottom, like 10.5:1. Then if you're ever on the bonneville flats, or in a road rally, you don't have to worry about your engine surviving.

Any ideas on if there are any provisions already in there, or how to set up a PE timer?

 

It should be AFR decay vs time in PE. I think I have seen it in some stock TBI ecms or perhaps it is just the EBL that I am thinking of.

The other reason to go so rich is to protect the catalytic converter and the exhaust valves/seats.

 

I found it! I can't believe it already exists! What luck!

from the P4 doc:

If vehicle speed exceeds *KPEHMPH*, and turbocharger boost mode is active, (Manifold Absolute Pressure, MAP, is greater than or equal to *KPEMAP4* (=1OOKPA)) for at least *KPEMPHTM* seconds, then the power enrichment air/fuel ratio will be reduced (air/fuel mixture made richer) by an amount *KPEAFDLT*.

I checked for those items, and they're in the bin!

 

The timer starts off of PE enable.
The trouble is, that once you lift, and then go WOT throttle, your *lean* to start. So you want a VSS AFR increase, and PE timer, well, that's what's worked out best for me.