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I tried Alpha-N based tuning for the first time on single throttle engine. I know MAP based tuning is the usual/preferred method but I just wanted to give Alpha-N a try and as an opportunity to try something new.
One thing I have noted while tuning was as the throttle is quickly closed from WOT, there is a small lag before a drop in MAP as air is used up in the plenum. Fueling wise, it looks fine probably due to the residual fuel evaporating from the walls of the intake runners as I don't see it running lean but I am a little concerned with ignition.
Even though the TPS is at a closed state, the MAP would indicate there is still a significant load in the engine. However, given the TPS is closed, the ECU would immediately start reading from the lower load parts of the map where usually much more advanced timing is used. Will this be concern? One of the main reason I brought this is up is because I often seen significant rise in knock sensor reading as the throttle is closed. I am not sure whether this is drivetrain noise or is this actual knock from the advanced timing.
This is a Syvecs S6 ECU. I don't think you can use different primary load for fuel and ignition?
No, I dont think it is the delayed MAP that is causing your issue. I see the high "knock activity" on a high RPM lift-off event on many engines - even those using MAP as the main load source for fuel and ign. I dont really know if it is backlash in the drive train or something like piston slap due to the instant low cyl pressure or the throttle blade hitting the stop hard or something else I haven't considered, but in my experience it is normal.
I woul be much more concerned the other way arround, if you suddently apply much more throttle. Means there is mire ign timing for a short time.
Hello Adrian, I think in my case, if I suddenly apply much more throttle, the ECU would immediate jump to the higher load part of my ignition map (as it is reference to TPS) where the ignition will be retarded, so I am actually decreasing my timing before MAP rises. Making it even more conservative/safe.