EA888 Low Pressure Fuel Pump (LPFP) Control

Owned by Lucan Hetherington
Last updated: Sept 29, 2020
3 min read

Introduction

The Low Pressure fuel delivery of the EA888 platform consists of a return-less fuel supply set utilising an electric Low Pressure Fuel Pump (LPFP) and a mechanically driven (electronically Controlled) High Pressure Fuel Pump (HPFP). This Article covers the Pressure control aspects of the low pressure fuel delivery systems on the EA888 platform.

The OEM fuel pump reportably runs out of fuel flow capacity at over 450hp (fuel type and model specifics), the extra demand required when running ethanol blends can affect the amount of fuel mass required to deliver that power so depending on the goals of your tuning you may need to upgrade pumps.

Fortunately there are many aftermarket plug and play pump and adaptors that can be fitted to cope with fuel demand for any power goal. for example

https://www.precisionraceworks.com/mk7/mqb-audi/vw-performance-fuel-pumps.aspx

https://www.getunitronic.com/parts/fueling/20l-tfsi-tsi-low-pressure-fuel-pump

Calibrating the LPFP control to deliver the correct fuel flow from the pump is done by setting the target, adjusting the feedback and the duty request output to the Fuel Pump Control Module (FPCM). Getting this calibration correct will allow you to supply the desired pressure to maintain the correct fuel flow volume and in a closed loop manner.

Basics

Low Fuel pressure in the fuel system can cause many different errors some of which can be catastrophic (lean AFR at very high boost) this doesn’t immediately mean that you need a new pump, filters, internal leaks and flow restrictions due to line size can also cause fuel pressure drops so make sure these are all addressed before upgrading.

You will discover when the fuel pump requires upgrading when the low pressure fuel supply cannot maintain the set fuel pressure. You should also see that the Fuel pump duty demand increases as the pressure drops below target trying to pump more fuel. If the duty is at maximum (100%) you will need to look into physical reason as Calibrating the system, you can adjust the LPFP Feed Forward maps to demand higher duty where required. it would not be recommended to run at 100% duty as there is no safety factor if the ambient conditions deteriorate.

Tuning

To tune low pressure fuel delivery the following steps will need to be performed.

  1. Set the target LPFP pressure to the desired amount. If running large amounts of boost you may want more pressure headroom for the injectors to accommodate for the return less non manifold referenced fuel pressure regulator.

  2. Set the fuel pressure target limits to allow your desired pressures

  3. Adjust the LPFP feed forward table (feed forward pump duty) to where you think it should operate depending on the new pumps capacity.

  4. log the pressure target, pressure actual and the duty and start slowly at low power adjusting the feed forward target to give the desired pressure with little corrections.

  5. Adjust the proportional, Integral and Derivative components (which modify target pressure based on pressure error).

The below diagram outlines the strategy overview.

The strategy is much more in depth than the above diagram with many error handling states and codeword switches to inhibit or allow certain corrections etc but these should not need to be adjusted unless there are issues with the normal calibration process or hardware.

If the strategy does not act as defined please contact support@ecutek.com for more information and detailed support.