Fuel pump issues

[xjohnx]

Originally Posted by jamesm

i finally figured out the problem. turns out it was in the tune. i was able to get in there and edit it myself and resolve the issues rather quickly. car is much happier now

What in the tune was causing it?

[jamesm]

Originally Posted by xjohnx

What in the tune was causing it?

port fuel injection ratio was set incorrectly for high load/rpm. the stock map has it using nothing but DI until about 6500 rpm or so when it feeds in a bit of the port injectors (like 20% iirc). had to modify it to use more port throughout that range. this is perfectly in line with my datalogs, where the afr was crazy lean until exactly 6500rpm when it would drop precipitously to the correct afr. it had just simply run out of DI flow capacity but was being told not to use the port injectors, if i'm understanding it correctly. in any case the car runs great and the afr's are perfect now

i also did various other things like adjust the stock wideband scaling, applied the transient timing fix, and a couple other minor tweaks that shouldn't effect fueling.

[tomm.brz]

Reupping old thread


is this value "fuel pump duty" relative only to DI injection? i mean a value of 90% duty, it means too much DI and DI injector are maxing out the high pressure fuel pump?

[steve99]

The di pump has pressure targets so its likely the pump duty cycle is based off the low pressure fuel pump




Looks like the fuel pump duty could be based on injector pulse width likely port and battery volts. May also be tied to throttle position or rpm triggers Would need to dissassemble rom coding to be sure. Looks like pump duty cycle is varied as the input parameters like injector duty cycle change.




http://www.romraider.com/forum/viewt...hp?f=40&t=8655