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HELP sensor issue on aem infinity

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pnp kseries harness car has been perfectly fine no issues. fired car up friday evening to move the car to another bay in the garage and to wash it. everything good then, but saturday mid day fired it up to load on the trailer for a race and i noticed my fuel psi was only reading 8-9psi (normally basse psi of 48), my map was reading a little over 200 kpa at idle, and my tps scale was off. i've tested all the wires and so far this is what i've found which is weird.

aem fuel pressure sensor. ground goes straight to battery, 5volt signal from the infinity pnp 5v output on auxillary harness, and the signal in from sensor to analog 9. with this sensor plugged in my map and tps gets thrown off. when i test the wires from the sensor the ground is not affected but the 5v and signal wires are. the 5volt reads .67 volts plugged into sensor but unplug the sensor and it reads the correct 5volts. on the signal wire it reads .67 volts plugged in but 5 volts unplugged. with the sensor unplugged my map and tps seems correct. ive tested the map and tps wires and the 5 volts are correct all the time but the signal wires are only affected when the fuel pressure sensor is plugged in.

my main question is how is my fuel pressure sensor/wiring affecting my tps and map? the fuel sensor wiring is completely seperate from the engine harness and goes straight to the infinity pnp auxillary harness for its 5v and signal which should have nothing to do with the map and tps. unless aem uses the 5v reference inside the ecu for the map and tps to jump it over on the pnp auxillary harness and somehow the sensor is bad and backfeeding through the 5v signal or 5v output. any help or ideas on what to test next would be great. i'm down now to buying two new aem sensors...map and fuel pressure just to rule those out. oh and i wired in a stock kseries map sensor and swithced over in the wizards and it still was reading off so that almost rules out a map sensor problem.

Sounds like a pretty odd problem! I'm not sure I have an answer for you unfortunately but one thing I will point out is that your fuel pressure sensor 0V needs to be wired back to a sensor 0V at the Infinity, not the battery. The ANV input from the fuel pressure sensor relies on an accurate and stable 0V reference and it's quite likely that if you wire this to the battery ground or a chassis ground that you'll end up with a small voltage offset that effects your reading accuracy - Not that this would cause the current problem you're seeing, but it's important regardless.

The only thing I can think of that might be causing the situation you're explaining is if the fuel pressure sensor has failed internally with a short from the 5V supply to ground or something similar. It's possible (I'm guessing here a little) that this could pull the regulated 5V supply down which could give you the situation you're seeing. I'd also carefully inspect your ECU power grounds and make sure these are sound and that you have little to no resistance to the battery negative. Poor ECU grounding can cause all manner of weird and hard to diagnose faults.

What happens if you wire a different sensor in place of the current fuel pressure sensor? Even just wire a MAP sensor you've got lying around to test the theory.

As Andre said, I would be starting with the Fuel Sensor, if the TPS and MAP work correctly with it disconnected, and then drop out when it is connected, then it points to an internal fault on the FP sensor. Did you use a pressure washer on the car when you where cleaning it? Quite often the pressure washers are able to push water past the seals on the connectors and into the internals of the sensor, causing faults.

no BlackRex just cleaned the outside no power washer.

Andre i think you are correct on you statements. i think there is an internal issue when the sensor went back sending something back through the 5v power and signal out that shouldn't be. i did find out like you said it needs to be grounded to the ecu not just a regular ground. New sensor should be here today and rewiring the ground at the same time. the reason it is messing with the other 5v sensors is because they are all ran through the same 5v circuit so that makes sense. I just hope once i rewire and new sensor the map reads ok now and i didn't hurt anything in the ecu. I'll post up results thanks guys

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