PE mode lag

[Draco]

Hi guys,

I'm trying to tune my vortech'd C5 (wideband equipped) and having a problem with PE mode lag. It's an SD tune but relies on the PE tables above 105 KPA. It seems that for the first 1/4 to 1/2 second after I go WOT, the mix is way leaner then commanded (i.e. 14:1 indicated, when 12.5:1 is commanded). It then immediately tracks the command AFR like it should by the time 1/2 second has passed. i have the PE delay completely bypassed.

Do I need to change my PE mode ramp rate settings? right now I have the ramp-in rate setting ( B3644 ) at the stock .006250 - which way would I adjust this to get enrichment going quicker?

What about the Commanded fuel step size? it's set to 1 right now, maybe going bigger will help?

Could someone please explain how B3643 and B3644 work?

I really dont want to trial and error this while in boost so any help is appreciated :).

[SSpdDmon]

To increase the ramp rate, you go towards 0.00 because it's measured in seconds. The stock settings say it will take 1/16 of a second to transition. However, I wonder if the 1/4~1/2 second delay you see is really a delay in fueling or just a natural delay in your WBO2 measuring your exhaust. Electricity travels faster than exhaust vapors. When you floor it, the PCM has to calculate how much more fuel is needed, increase the amount of fuel delivered, which then goes through the combustion process before it's finally read by the WBO2. From the PCM side, this seems like it happens instantaneously. To say this will happen instantaneously from the WBO2's perspective is fairly unreasonable. So, part of the delay is natural. Try changing the ramp in number to .000001 and see if that helps some.

I'd leave the step size alone. It's set aggressively from the factory at 1.00. That setting translates to the PCM allowing a transition from 14.6AFR to 7.3AFR in 1/20 of a second.

[Draco]

Thanks for the reply man, I will try your suggestions.

I dont think this is an exhaust gas reading lag issue. when DFCO hits, the AFR changes nearly instantly. the PE enrichment comes in WAY WAY slower, even at higher RPMS where the exhaust gases should be moving very quickly.

part throttle enrichment also seems to come in much faster then the PE enrichment (below 100 KPA using the Open Loop commanded AFR table).

I'd love to know the actual calculations or operations the PCM uses with these ramp rate and step size values. Does anyone know?