jh4db536

going back to my original question.

yes i understand that ECU by itself or with the VAFC does NOT compensate for Fuel at WOT/Open loop mode - the VAFC is only useful in this "Window condition".

The VAFC modifies the MAP signal in order to achieve its fuel enrichment or cut settings. The VAFC is only connected to the MAP sensor input and vtec solenoid output and NOT the injectors directly. By modifying the MAP signal, Fuel AND Ignition timing are permanently altered by the VAFC (at least fuel is?) because the ecu doesnt compensate for Fuel? during the Window condition.

My question is, so what if the engine made detectable knock during the Window. The ecu would step in a retard timing DURING the window or not? Can fuel cutting with the VAFC lead to knock from the timing change?

I understand that this is a limitation with the VAFC - it cannot Independently modify timing and fuel, but it does actually modify both with a Functional relationship.

H22toF20

If compenstate means counteracting or counterbalancing, then THE ECU DOES NOT DO THAT AT WOT, it only tunes out narrow throttle we are talking about fuel, now timing is another thing
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You are referring to open loop vs closed loop. Mostly the ECU won't make adjustments at WOT, sense it's in open loop; it literally doesn't read off the O2 anymore. But the fact that a VAFC can alter fuel(and timing) by altering the MAP signal, proves that SOME adjusting is going on during WOT.

JUSTINTHECOASTIE

If compenstate means counteracting or counterbalancing, then THE ECU DOES NOT DO THAT AT WOT, it only tunes out narrow throttle we are talking about fuel, now timing is another thing
[/quote]
You are referring to open loop vs closed loop. Mostly the ECU won't make adjustments at WOT, sense it's in open loop; it literally doesn't read off the O2 anymore. But the fact that a VAFC can alter fuel(and timing) by altering the MAP signal, proves that SOME adjusting is going on during WOT.
[/quote]
Is it noticable?

H22toF20

^I've never used a VAFC and wouldn't know how to read the adjustments in timing.

I know it's counter productive, but I wonder if you can hook one up with an EMS and datalog the differences in timing and pulse width.

JUSTINTHECOASTIE

No time
OP get your numbers pulled and go from there, we gave you ideas to work with and our experience(s)

s2konroids

Don't forget that when leaning out via a VAFC2 etc (ie via the map sensor method) you advance timing inadvertantly...not good especially F/I but also potential dangerous even when N/A. You may get away with it depending on how far you push it and your car.

s57_s2k

your reading is just like mine , in my car when the vtec kick in (yo!!) around 6000 rpm my AFR reading jump to 14 (external wideband) .