M400: Fuel pressure monitor

[mr2andy]

Hello,
Is it possible to have a fuel pressure sender unit sending pressure information to M400 and if the fuel pressure drop under certain psi, have Motec shut down the engine?

Cheers

[Dragon]

Yes, sure. We normally use either TI or Honeywell sensors for this.
To cut, you can set up Fuel Comp 2 table and use fuel pressure as X axis.
Put in -100 at the pressure where you want the engine cut.
I have not tried this but it should work.

[mr2andy]

Thanks for the response... buddy..

I plan to run base fuel pressure at 50 psi and I have a 1:1 Fuel pressure regulator. Is it possible to have the x-axis as the base fuel pressure + the map sensor reading so say if I'm boosting at 20psi, fuel pressure should be 50+20 = 70 and if the fuel pressure reading from the sender unit didn't not read 70 or at least 70 x 80% = 56psi, then the engine will be shut down.

By the way, what you mean by putting -100 in there?

[Ben-S]

Your better of using it as an axis in your rev limiter table (if your not already using both available axis) if you chose to do it the way mentioned above it's extremely important you don't give the ecu any room to interpolate, the last thing you want to do is lean out an already lean engine as it interpolates between what would most likely be a notable positive number (making up for the low fuel pressure) and -100

[mr2andy]

Guys..
excuse my knowledge in Motec manager software as I'm still learning...

Seems like the -100 is the trigger value for the ECU to shut down the engine?

[RossB]

The - 100 value they are referring to is a fuel trim, this would trim the fuel to 0. If you are using fuel pressure as an input for any type of compensation make sure that you use a decent sensor like the Honeywell sensor. Also you will need to use a filter value of about 4 or 5 if you are using it on a table and set a sensible default value. The filter will affect how the fuel pressure appears in your logging because the filter is applied to the channel at the input stage but there is a way to have a filtered channel for your compensations and an un-filtered value for your data logging. You can set up a User Channel using the same input and calibration as the Fuel Pressure input but leave the filter value at 1. You can call this User Channel something like "Fuel Pressure Unfiltered" and use this channel for data logging purposes.

[Wolf_Tm250]

Hello,
Is it possible to have a fuel pressure sender unit sending pressure information to M400 and if the fuel pressure drop under certain psi, have Motec shut down the engine?

Cheers

I would use a differential pressure sensor between manifold and fuel pressure, and use it in an Aux Comp Table for fuel cut:
it would be way useful because it'll analyze FP-MAP and find eventually a fuel pressure regulator and fuel pump problem even when FP is more than zero.

[mr2andy]

Hello,
Is it possible to have a fuel pressure sender unit sending pressure information to M400 and if the fuel pressure drop under certain psi, have Motec shut down the engine?

Cheers

I would use a differential pressure sensor between manifold and fuel pressure, and use it in an Aux Comp Table for fuel cut:
it would be way useful because it'll analyze FP-MAP and find eventually a fuel pressure regulator and fuel pump problem even when FP is more than zero.

I never heard of a differential pressure sensor. How does it work?

[Wolf_Tm250]

Hello,
Is it possible to have a fuel pressure sender unit sending pressure information to M400 and if the fuel pressure drop under certain psi, have Motec shut down the engine?

Cheers

I would use a differential pressure sensor between manifold and fuel pressure, and use it in an Aux Comp Table for fuel cut:
it would be way useful because it'll analyze FP-MAP and find eventually a fuel pressure regulator and fuel pump problem even when FP is more than zero.

I never heard of a differential pressure sensor. How does it work?

You connect 2 pipes to it, and it senses the differential pressure, giving you a voltage...

As I told you, you can connect fuel pressure and manifold pressure, and get a CONSTANT value AROUND the base fuel pressure (for example 300 kPa):
when this constant is out of a range ( for example 270 to 330 kPa ), warning light comes up, indicating a fuel pump or a fuel pressure regulator problem or a leak...

Wolf