shinckley08
Active Member
I monitored trims over a longer period of time and generally things rarely seem to go out of normal, but I have edged in on a few things.
I also watched fuel rail pressure and trims while trying to reproduce, and it seems that when I go off throttle and pressure drops it’s not recovering very quickly and producing a lean scenario. This clued me into how to more easily reproduce the sound. At low speed and relatively low RPM come to a stop and quickly apply very light throttle.
What I think is happening is at Higher RPMS the HP fuel pumps are maintaining pressure fine, but at low rpm’s, after a pressure drop, they can’t. Just a theory, no clue what I’m doing.
This all has me thinking it’s a fuel delivery issue from the low pressure pump, or a failing HPFP.
One other thing is that is seems to be worse on a very empty tank, which to me would point toward low pressure. Ie, mass is helping with the pressure.
I should mention steps I took prior have resolved the MPG issue, I’m about 14 in town running premium and back to what I’d expect with my roof rack on.
I also watched fuel rail pressure and trims while trying to reproduce, and it seems that when I go off throttle and pressure drops it’s not recovering very quickly and producing a lean scenario. This clued me into how to more easily reproduce the sound. At low speed and relatively low RPM come to a stop and quickly apply very light throttle.
What I think is happening is at Higher RPMS the HP fuel pumps are maintaining pressure fine, but at low rpm’s, after a pressure drop, they can’t. Just a theory, no clue what I’m doing.
This all has me thinking it’s a fuel delivery issue from the low pressure pump, or a failing HPFP.
One other thing is that is seems to be worse on a very empty tank, which to me would point toward low pressure. Ie, mass is helping with the pressure.
I should mention steps I took prior have resolved the MPG issue, I’m about 14 in town running premium and back to what I’d expect with my roof rack on.
