mark kibort

Based on RPM and the flap deflection voltage. I think that enrichment is just a 15% shift of the curve, so if the flappy is maxed out, there is only the preprogramed map modified by the only inputs left, which are air temp, and pressure. O2 is ingored at any time throttle is 75% or more. (ie open loop)

Like i said, you can put a fluke meter on the flappy voltage and see what percentage of max flap you have. there is some slop, as your voltage measured with the engine not running, is different than when the car is running. (1- 1.5 volts) the manin thing is that you can see how much air mass flow your car is producing by this voltage. the more HP i got to the ground, the higher the voltage i got, until it was near what i thought, was max. that was at near 293hp at the wheels. not bad through a 4 square inch restrictor plate , uhhh, i mean AFM. (and if it did get maxed out , fuel was provided based on just RPM.)

mk

toofast928

Ok so to wrap this up. The Q is "How does L Jet compute A/F ratio after the AFM is maxed out?", about 3000 RPM. I spoke with a BMW trainer that once was a trainer for Porsche. For high speed engine operation the 928 version of L Jet follows a program just based on RPM input. The contoller has no input of air flow (AFM maxed) air temp is a small modifer.
The system is air volume then crude speed density.

mark kibort

When you max out the AFM, which is kind of tough, you get what you get. the Ljet doesnt know that more air is passing through, as it is MAXed out! So , at that point, if the engine can increase displacement, or a bigger cam can draw more air mass , the engine will only get the fuel load as if the AFM is at max, and will only change to RPM, which it does anyway. what you then do is increase fuel pressure, so for the injector duration , you get more fuel flow and you can optimize at certain rpm and air mass flow ranges.


for example, at 294hp at the rear wheels, the stock injectors were at 90%, and fuel air mixture was at 12-13 :1 from 4000rpm to 6400rpm. the engine only went lean from 12.5:1 after 5900rpm.

the system is mass flow metering in the pure sense of the term. (until its maxed out) PV/NRT. this is the reason that i only had to fine tune the system to go from 175hp all the way with 294hp. the device metering the air and keeping the mixture right was the AFM, until it was maxed out. then, i added fuel via the fuel regulator to opimize the mixture and make it safe to 6400rpm


Mk