[ivanj308]

Just switched from a Dinan Elite V1 to a MHD Stage 2 93 Tune.
Car running Shell Vpower 93
Logs are showing low and erratic fuel rail pressure

Fuel system has never been touched.

Is there a fuel rail pressure calibration that needs to adjust since the Dinan Elite v1 has been removed ?

Fuel Filter ?

Any ideas are welcome.

Log below

https://datazap.me/u/ivan308/log-158...g=0&data=25-26

[G.Newt]

https://datazap.me/u/ivan308/log-158...2-5-8-25-26-33

Right when your rail pressure drops, you can see that your boost has overshot target slightly. The difference increases where it overshoots by nearly 1 psi. This happens at the valley in the rail pressure.

This kinda looks like throttle closure. But unsure how that impacts rail pressure.

[alyabiev]

Originally Posted by G.Newt

https://datazap.me/u/ivan308/log-158...2-5-8-25-26-33

Right when your rail pressure drops, you can see that your boost has overshot target slightly. The difference increases where it overshoots by nearly 1 psi. This happens at the valley in the rail pressure.

This kinda looks like throttle closure. But unsure how that impacts rail pressure.

Please STOP using boost as reference. Load is the main measure used as axis in almost every table in the ECU, not boost. ECU targets load from driver's input and only then calculates the boost needed to reach the target load.

You can clearly see that FRP drops at the late spool and slight load overshoot. Usually that kind of "overload" results in throttle closure but does not trigger such pressure drop.

From my experience with other DI engines, not every HPFP is created equal. Some of them hold the pressure, some do not. My bet is HPFP just can't pump more, that's it.

[kern417]

Originally Posted by alyabiev

Please STOP using boost as reference. Load is the main measure used as axis in almost every table in the ECU, not boost. ECU targets load from driver's input and only then calculates the boost needed to reach the target load.

You can clearly see that FRP drops at the late spool and slight load overshoot. Usually that kind of "overload" results in throttle closure but does not trigger such pressure drop.

From my experience with other DI engines, not every HPFP is created equal. Some of them hold the pressure, some do not. My bet is HPFP just can't pump more, that's it.

Regardless, It doesn't make sense that the hpfp is hitting the limit at 17psi on 93 octane.

OP - This might sound dumb, but did you remove the V1 before flashing MHD? If you're running a boost controller piggyback then you'd actually be running more boost than the log indicates.

[ivanj308]

Yes Dinan has been removed.

Is the fuel pressure low enough that I need to be concerned that the car will run lean ?

Any ideas for troubleshooting ? Flash back to stock and log ?

[kern417]

Originally Posted by ivanj308

Yes Dinan has been removed.

Is the fuel pressure low enough that I need to be concerned that the car will run lean ?

Any ideas for troubleshooting ? Flash back to stock and log ?

It won't run lean but you can go into limp mode if the fuel pump crashes. Yes, you are in that region.

You can try logging stock or stage 1 to see if the issue persists. Also log AFR at idle to see if there's an injector/fuel pump issue.

[ivanj308]

AFR at idle are solid

Can fuel pressure be adjusted with a custom tune or is this just a mechanical issue ?

Do I replace stock pump. I am guessing there are a few used stock pumps available for sales as people have upgraded.