Fuel Pressure model

[CarloL]

Hi

I have an M1 Partner package , When fitted with a fuel pressure sensor, fuel pressure is part of the model and will be compensated for.

Trying to weight in cost versus benefit, is it worth fitting a sensor and associated costs to take advantage of this feature?

What is the benefit ? lower Fuel consumption?

[DentGuy]

Fuel pressure data is a huge part of how the ECU will calculate the final injector duty. With a true VE fueling strategy I feel a fuel pressure sensor is a must.

[Stephen Dean]

As DentGuy said, the use of fuel pressure in the VE model is a major part of the fuel volume calculation, as well as the Injector Differential Pressure calculation, so if you do not have a FP sensor, you need to make sure that the Fuel Pressure Default value is correct, and that the type of FPR that you are using is specified. If you use an FPR that has a non linear relation to the change in manifold pressure, I definitely would have a FP sensor installed.

Another area that catches people out is the Default value for the Fuel Temp, this can greatly effect the Lambda value if it is incorrect.

[CarloL]

Thanks Guys!

[CarloL]

Just on the Default value for the Fuel Temp; this will change with weather conditions (mainly seasonal)

Unless you have a sensor you really dont know, Are you better to set the default to higher or lower temp?

It is estimated Temp 30

Pressure default is set at 325Kpa , taught this would be set closer to 280Kpa

Toyota GTE Service Specs...
Fuel Pressure at Idle w/vacuum hose disconnected is 33-40psi (2.3 - 2.8 kgf/cm)
Fuel Pressure at Idle w/vacuum hose connected is 24-31psi (1.7 - 2.2 kgf/cm)

[Ryan]

Where is a good spot for the fuel temp sensor? I have one in the fuel tank but would closer to but not in the rail be better?

[David Ferguson]

You need to measure the fuel temperature and pressure of the fuel going through the fuel rail. I made up this manifold that replaced the end-cap on my fuel filter to provide ports for both temp and pressure.

[Stephen Dean]

If the default fuel temp is higher than the actual fuel temp, then the car will run richer than aim, and vice versa, so you are better off to have it set at a higher than ambient temp than lower.

[Scott@FP]

Fuel temp in the return line somewhere usually works well. If its a returnless system it needs to be in the rail.

[CarloL]

Was looking at my M1 package again last night , My Sytec FPR installed by my Motec mapper is "Manifold Pressure Referenced" FPR but he has selected Ambient in the firmware

What are the implications of this?