Might be a dumb question but can someone confirm my thoughts on this??? I would assume that the Pe min RPM for decay setting would be so that Pe starts to decay at that RPM?? So if the stock setting is 2000RPM, Pe will be in untill 2000 and then it will start to decay after that. So IF I set PE decay RPM to 3500 I should get a longer pe cycle. Is this a correct way of thinking?? Or can someone give me a better explanation of Pe decay vs RPM?? PLEASE. Its a 7747 using $42 and tunerpro. Thanks

 

Come on guys someone has to have an explanation or opinion!! Fast or Dimented Are you out there?? THanks

 

I could be wrong, easily......
Last I'd hear anything about PE decay, had to do with "decaying" the AFR to something richer, to cool the engine and CAT.
Which what where are you looking at for this decay number ?

 

In my 7747 $42 bin there is a setting for Pe min RPM for decay. The factory setting is 2500rpm. Im wondering what exactly this effects?? Apparently not to many people have seen it etc. Im using the 7747mine xdf file or at least last time that i looked.

 

Watch for typo's in definition files you didn't create yourself, like the one you found !!
Methinks you'll find that entry is for a PE "extra spark advance" decay, not for PE fueling at all !

 

Ok thanks that could definatley make sense Now what would Pe spark advance decay do. Start to take out spark at that RPM or something else. If its starts to take out spark at 2500rpm I would definatly want to change that?? Thanks again

 

I don't personally know for sure, as I never got my main spark map close enough for my tastes while I was running that ECM. ( had "extra" spark tables zero'd out for tuning main )
If I was gonna guess, I'd guess it's to promote combustion cooling the longer you stay in PE, but that would be strictly a guess.

 

how fast the PE spark is bled out after exiting PE, probably
If you have like 2 or 3 degrees in the PE SA table, this is what is bled off. not 100%, but this is probably the function of the table.

 

Also not sure, but it sounds like what Cflick is saying is right, in that it's a decay of the PE air fuel ratio, to a richer value. Trucks needed higher throttle angles for doing normal things, and below 2500 the cats can probably survive at stoich air fuel ratio or normal PE. Not sure if this PE decay is extra extra fuel, or if its going from no PE to PE in a delayed manner.

Find a commented hack, and read it for yourself - might find a few other surprises in there as well.