AlpineFD

I recently installed a fuel pressure sensor on my car, NA AP2 engine with bolt ons, stock fuel pump, stock FPR, stock fuel rail.

but what's odd is the data is wildly fluctuating between 0 to 90 psi on full throttle runs.
I verified the sensor calibration is correct (aem ecu, aem sensor)
the fuel pressure sensor reads correctly at idle
injector duty cycle and AFR appears normal

any idea what could cause this?

the fuel sensor was installed by tapping a hole on the stock fuel rail, then plumb a fuel hose from the rail to the fuel sensor.
I'm assuming the shop did this to give it a clean install.
I'm not sure if this install method is what's causing the pressure fluctuation reading, but even if the hose is causing some fluctuation, why would it go up to 90psi?

snitm

They screwed the fuel pressure sensor onto the end of a fuel line branched off the fuel rail!? That is why you're having problems. It isn't measuring the actual flow through the rail. It is measuring the flow into a dead-end.

flanders

It's a pressure sensor, not a flow sensor (that would be pretty cool to have though) so I doubt the placement would cause these kind of problems.
Have you done a calibration on the actual sensor? Applying known pressure to the sensor and verifying it reads correctly the whole range.
Does the sensor need to be grounded? Using a rubber hose could then cause problems.

PaddyMcP

Installing the sensor in that location is perfectly fine, and will give accurate readings. It's actually very sensible as it will let the sensor live longer being isolated from the engine vibration on the fuel rail.

Can you post the sensor type, ecu type, and calibration table?

Pressure sensors are usually 3 wires, a 5 volt sensor wire to the 5v pin on the ecu, a 0v or sensor ground wired to the 0V pin on the ECU and the signal wire that carries the variable voltage level back to the Analog input pin on the ECU.

Can you verify you have it wired right and that you have continuity on the harness pin to pin?
-Paddy

AlpineFD

Hi Paddy !

thanks for responding, sensor is AEM 100PSI stainless sensor (30-2130-100, ECU is AEM EMS Series 2, calibration is the default AEM calibration for this sensor.

sorry i have no idea about eletricals, could you elaborate how to perform this continuity test? i do have a multimeter.