MoTeC Global Forum

Is there a table to set starting fuel pressure on the M1? On the weekend we were testing after switching the car off the fuel pressure started climbing due to heat soak, it got to 10.5bar which is quite high the engine didnt want to start again. Only after the pressure was releaved but cracking the pipe of open it started again. Where do i set this value?

Thanks

What tables your M1 has are entirely dictated by the firmware package you are using. Can you tell us about the firmware package, your engine and fuel system (sounds like perhaps it's a return-less system that doesn't have a pressure regulator). What is your normal fuel pressure?

Do you have a fuel pressure sensor connected to the M1? I would have expected that along with proper injector characterization to compensate for any pressure increase.

Hi,

As David stated, some more information about the Package and Vehicle will assist in answering the question for you.

The latest versions of the GP Packages have had a Fuel Pump Control system added into them, this may assist you with your issue.

Hi Guys
Its an LS-7 engine and has a fuel regulator set to 4.5bar. Pressure sensor is connected to the M1
Im using firmwhare version 01.01.0006
Its almost like the max cranking fuel pressure is set to 10bar and if it goes over that it wont start, like as if the ECU sees the engine is flooded.
In the M1 my "Engine crank flooded throttle position" is set to 90%

Thanks Donovan

I would replace the fuel pressure regulator! Sounds like it's not functioning properly if it can not regulate the fuel pressure to keep it at 4.5 bar.

Do your Injector Linearisation tables go to 1100 kPA? Most of the ones I've seen don't go that high, and I could imagine that if the pressure was outside the linearisation table range that the firmware may not open the injectors (and thus lower the fuel pressure in the rail). You could try adding a data point to the Linearisation axis for Fuel Injector Differential Fuel Pressure for say 1200 kPA and follow the trend of the previous other data you have. Hopefully after a few cranks the fuel pressure would drop and you'd be using accurate data.

Note you have to create the data for all the Battery Voltages, and then copy the data for each injector (use Component->Export->To Clipboard, and Import->From Clipboard)

Hi,

The M1 will try and open the injectors when the pressure is over the maximum value in the linearisation table, but will not be as accurate with their fuel delivery.

What errors are you getting with the injectors at this point? are the Peak Hold or Saturated injectors? It may well be that the reason for the injectors not opening is that they are not capable of opening against that pressure, especially at cranking voltages.

Are you even using the ecu to try and control fuel pressure ?

You seem to suggest it has a normal mechanical fuel pressure regulator ?

Using saturated injector and a mechanical fuel regulator. It does seem that the injector cant open when the pressure is so high, i will have to cover the fuel line with heat shield to prevent the heat soak and maybe also rethink the position of the one way valves. Dont think there is much else i can do.
Thanks guys

So in no way whatsoever is the ecu controlling fuel pressure ?

Why are you trying to run 10 bar ? on what sounds like a conventional injection system ?