A couple of reports have come in from people who want to use AlphaN now that they have poor MAP signals due to long duration cams. It seems that they can never get their cars to idle particularly well. On further discussion it seems that the cause for this is that the IACV opens allowing more air in, but then there's no additional fuel added, so that the AF mixture goes lean and the idle gets progressively worse.
With our Speed density system, when the IACV opens, the pressure increases and the fueling and ignition requirements are better addressed.
As we tie the MAP value to TPS in our AlphaN system we need to model the same MAP pressure change when the IACV is opened.
Here's how I think it could be done.
Add an additional config entry IAC_OPEN_TPS_VALUE (%) which will be setup to equate to the equivalent change in throttle position that the IACV gives when open. The actual change would be dicatated by dividing IAC_OPEN_TPS_VALUE by theIAC position or duty.
So with an IAC_OPEN_TPS_VALUE of 4% when the IACV duty is 25% it will consider there to be a TPS opening value of 1%
We could use the config byte fuelcut_min_kpa as that's never used when in AlphaN mode.
emil's thoughts
Is it really necessary with IAC valves for a highly tuned engine like that? It just makes it even worse to tune
What happened to the good old idle screw? Works good on our cars here. A 300+ deg camshaft and ITB's is not anywhere stock drivability and is not supposed to be driven around on idle. I am pretty sure that a idle screw will work better than any IAC solution on these cars. I would say that it is not worth to invest in developing stuff like this.