TastyBacon

I am already logging my wideband through the EGR input. I'd like to start logging fuel pressure too; I know the most common way is through the A/C pressure input, and to put it on a toggle switch if you still want A/C to work. I was thinking about how I'd like to do this on my car and came up with another option...why not use the oil pressure input, with a similar toggle switch setup? They even read in the same pressure range, so with the correct 0-5V sender, you could theoretically switch between having oil or fuel pressure displayed on the instrument panel / DIC, which would be cool. Has anyone else ever tried this?

RonSSNova

TastyBacon

Very cool, thanks! I am running a turbo/boost-referenced setup as well. Yes, all the aftermarket sensors I've found are either 0-100 or 0-150. I'll have to see if I can find a way to adapt one to read close to the correct scale.

C6_Racer_X

I would caution against this. Isn't the oil pressure sensor the one that the PCM uses to turn off the fuel pump relay? No oil pressure = turn off fuel?

If that's the way things operate, you don't want the "oil pressure" reading to the PCM to be the fuel pump output. In the event you have an accident, and a fuel line is broken, you want the pump to shut off when the engine stops. If it's still reading pressure from the fuel line, and the fuel pump keeps running, you will have a very serious hazard.

I know it sounds like a remote possibility, but I know someone who spent over a year in the hospital because of a rigged fuel pump relay. He got in an accident, and the fuel line broke and was aimed at the exhaust manifold. The pump kept running and pumped almost a full tank of gas into the fire. He was in bad shape after that accident. I wouldn't want that to happen to anyone, ever.

Now, if the fuel pump still shuts off based on some other signal to the PCM, it would be safe, but I'd make damned sure that safety feature isn't affected by what you're doing. Test the thing before you assume anything.

You don't ever want to change your handle here from @TastyBacon to @CrispyBacon


PS. Is yours a manual transmission?

TastyBacon

Thanks for the reply; I'm sorry to hear about your friend. Yes, it's a manual. I don't think the PCM works that way; my oil pressure sensor has failed and has been unplugged for a couple months now. It reads -15psi on logging software, but the car still works just fine, except for a "Service Engine Soon" message on the DIC after starting the engine that can be cleared with the Reset button.

C6_Racer_X

With a manual, it's fairly easy to check.

With the engine running, engage 4th gear and let the clutch out. Yes, stall it that way. With the key still on, and everything active, see if you hear the fuel pump running, or if you have voltage at the pump. You can also see if fuel pressure falls to what it does after the pump shuts off (the key off), or if it stays at pump running pressure.

15 psi is generally above the cutoff threshold, so you might find out your pump is running all the time. If it is, fix that soon. As I pointed out, that's a big safety issue.

OOPS. I just realized you said it reads -15psi. Never mind. I'd still want to verify that your pump is cutting off like it should. I'm kind of paranoid about that.