tunermt

While tuning I often have people ask me what they can do to ensure their engine remains reliable and making good power for as long as possible.
Besides the obvious hardware requirements/clearances and general maintenance like lubricants there are a few key sensors that can be incorporated into the ECU and dash display that can not only increase engine performance but also save an engines life if there is something as simple and common as a fuel pump failure or clogged fuel filter.

This article goes into light detail about the Fuel Pressure sensor and how it can be incorporated into a calibration by the tuner to not only help your engine run efficiently but also keep it safe and healthy. This little read is HIGHLY recommended for anyone that "pushes" an engine on the track or the street. You will quickly see how a low cost part can save a high cost engine!

Fuel pressure sensors, gauges and engine safety explained




Explanation: Assuming a fixed injector open time an injector flows a given amount at a set fuel pressure; more pressure - more flow, less pressure - less flow (assuming same given injector open time). If your engine has been tuned with 50psi fuel pressure/injector differential pressure and 6 months later your dirty fuel pump starts to die fuel pressure will fall off first at high RPM/high engine load. This is where the pump needs to flow the most fuel, this is also the most vulnerable operating range for an engine so any loss in fuel will quickly cause a lean condition leading to damage.

Solution: Assuming your car is using a proper motorsports ECU such as; Motec M1, AEM Infinity, Haltech, Bosch, Pectel, etc we would incorporate a 3 wire fuel pressure sensor into your calibration aka “ecu tune” in a number of helpful ways to ensure accurate fueling AND fail safe features in case of some type of mechanical failure.
**Even in the case of stock ECU tunes it is possible to incorporate a crude fuel pressure fail safe that drops boost back to waste gate pressure to help protect the engine in case of fuel pressure drop under a WOT pull.

tunermt

AEM 150psi sensor installed on the Velocity Element rail using a 1/4npt to 1/8npt fitting.

tunermt

Got a little CD5 dash in the mix now and set up some nice warnings and alarms to suite the little SR20det in this car. I'll post some examples of the custom layouts and warnings shortly, until then here is one of the AEM supplied layouts i adjusted lightly to better support this engine.

rip

can you install a fuel pressure sensor into the AEM fp regulator or is it more advisable to get the reading off the fuel rail?

tunermt

You can install the sensor on in the regulator no problem if the regulator is set up in the return fuel line coming off the fuel rail.
In this E30 the regulator is in the trunk (modified dead head set up with the return line off the regulator back to fuel cell and only 1 fuel line to the fuel rail) i want to see exactly how much pressure is in the fuel rail do to this configuration and compare to pressure at the regulator.

tunermt

Out skidding around in the E30 the other week just before my Japan trip and i let the fuel cell get a bit low, finally saw a low fuel pressure warning pop up on the cd5 dash and when i went to go have a look at the log i could see fuel pressure fall off as the ECU compensated to hold a steady AFR and then cut spark and fuel as soon as the fuel pressure dropped beyond the set boundary. I'll try to recreate this type of situation again and save the log to post some screen shots.

tunermt

Random tip for those adding a fuel pressure sensor to your fuel rail. While the rail is out check the injectors and injector filters! (some will place the filter in the "top hat" as pictured and others will be in the actual injector body.)
Injector Dynamics inspection