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Does anyone know what empty pin I can use to add a fuel pressure sensor to a E38? I want to be able to log fuel pressure when I'm plugged up to the OBDII and scanning and I don't want to deal with adding a gauge or running wires to the pro. Looking to be able to plug into the OBDII and go if possible. System is return style and FPCM is no longer installed. Thanks!
ive been searching for the answer to this question. did you ever figure it out?
Does the stock fuel pressure sensor no longer work?
Guess not, I just now realized the fuel pressure sensor is wired into the FPCM. It likely reports fuel pressure on the CAN buss. The ECM doesnt appear to have a specific input for the fuel pressure sensor. Not sure how people are handling this aside from using an aftermarket gauge.
Just finished up a return style install myself recently. I retained the FPCM and just turned off a couple of codes. Pumps are controlled by relays so FPCM is only there for fuel pressure reading. Is it an option for you to reinstall it?
Fuel tank pressure sensor is a normal 0-5v 3-wire. Only available to use if EVAP stuff has been disabled though. There aren't any unused inputs sitting around like in the old days, and even back then the EGR only existed because it really was used in some applications. In later ECMs where none of them used EGR the EGR pins went away.
In E40 & E67 some platforms used a 3-wire sensor at the brake booster (basically a redundant MAP for DOD stuff) but I don't think any E38 platforms used that sensor, so the pins probably aren't there (and if the pins are there but nothing ever used it, it doesn't appear in any diagrams/pinouts). And besides, VCM Scanner doesn't acknowledge the brake booster sensor even exists on the E40/E67 vehicles, so it can't be logged or even displayed. I asked for it to be added and nothing ever happened.
Personally, I'd just get one of the AEM gauges that has a CAN output, and be done with it. I know they have inline types for the widebands that dont require a gauge, not sure if they offer that for fuel pressure though.