97 Cobra/oil pressure sending unit/O2 Sensor

[cfriedman67]

I have a 97 mustang cobra engine and I am also using the Ron francis wiring harness. To hook up the oil pressure sending unit with the FFR gauges you need to replace the Oil pressure sending unit with the new one that is supplied by FFR. The new one does not have a place to attach the wire that comes off the O2 sensor wire. Does that wire need to be connected?

Thanks
Craig

[walt mckenna]

Could you clarify the problem a little more? Is the Oil pressure sending unit wiring part of the 02 sending unit wiring in your scenario? Is the Ron Francis wiring loom part of the issue?

[cfriedman67]

Absolutely. 97 Mustang Cobra engine, Ron Francis wire harness, FFR Vintage Speed hut gauges. I am starting to do the wiring for the gauges. In the directions it states;
Remove the Ford Oil Pressure sending unit from the driver side of the engine in front of the header with
a ¾” wrench.
2. Wrap the threads with Teflon tape and install the sender in engine.
3. Run the gray cable from the gauge to the sending unit.
4. Attach the ring connectors to the gray cable wires.
5. Attach the connectors to the sending unit, either wire ca go to either connector.

The original sending unit that I removed attached to the O2 sensor wire harness. I guess my question is two parts. First, do I still need to attach the O2 sensor wire harness to the new Oil pressure sending unit with the new gauges? Two, if I do how do I do that? I have attached pictures of the original sending unit and the O2 Wire harness with the connection in question circled in red.
7585275853

[phileas_fogg]

Take this with a pound of salt, because I have no experience with the 97 mustang cobra engine or its O2 sensor.

But I would guess that Ford bundled the oil pressure sensor wires and O2 sensor wires into the same harness simply for convenience. Now that you've replaced the oil pressure sensor with one compatible with the Speedhut gauges, you don't need the Ford set of oil pressure sensor wires. You can either leave the Ford connector dangling or remove it from the Ford harness. You DO need the O2 sensor wires, so you can't get rid of the Ford harness altogether.

A possible wrinkle is if your engine has EFI and if that EFI computer requires oil pressure to operate correctly. My Holley Terminator EFI does NOT require an oil pressure input, but that's the only EFI system with which I have any familiarity.

Hopefully someone with more experience can confirm or refute my thinking.


John

[Joecobr]

Take this with a pound of salt, because I have no experience with the 97 mustang cobra engine or its O2 sensor.

But I would guess that Ford bundled the oil pressure sensor wires and O2 sensor wires into the same harness simply for convenience. Now that you've replaced the oil pressure sensor with one compatible with the Speedhut gauges, you don't need the Ford set of oil pressure sensor wires. You can either leave the Ford connector dangling or remove it from the Ford harness. You DO need the O2 sensor wires, so you can't get rid of the Ford harness altogether.

A possible wrinkle is if your engine has EFI and if that EFI computer requires oil pressure to operate correctly. My Holley Terminator EFI does NOT require an oil pressure input, but that's the only EFI system with which I have any familiarity.

Hopefully someone with more experience can confirm or refute my thinking.


John

I have a 98 Cobra engine, the RF harness and an Art Cuesta diet on my OEM harness. You are right, the oil pressure connector is contained within the O2 harness. I deleted this connector and installed the new oil pressure sensor and connected it with the proper RF sending unit wire. Art also labeled a wire from the other end of the OEM harness on the passenger side that is connected to the gray RF oil pressure wire behind the dash. This picks up the oil pressure signal for the computer.

[cfriedman67]

Hi Joe,
I also had Art due the diet to my wire harness. I don't have my harness with me but I'm assuming mine is labeled as well. When you say deleted the connector did you actually remove it or just cut it off? Also, Did you need to use any other of the OEM wires to hook the dash up? Any help would be greatly appreciated.

thanks

[Joecobr]

I unwrapped my complete engine harness and O2 harness. The O2 harness is connected to the driver’s side end of the engine harness. When eliminating a connector I generally cut it off somewhere inside the harness and heat shrink the end to ensure no shorts.
There are quite a few other wires that Art labeled that must be connected with RF harness wires behind the dash. I am away from home so don’t have access to any pics at the moment. When you read the labels Art provides and study the RF wiring diagram it all becomes fairly straight forward...as long as you don’t start getting fancy with additional bells and whistles.

[cfriedman67]

I have labels for check engine light, water temp sensor, vehicle speed sensor + and -, oil pressure sending wire, and tach signal. I would think I would not need these? The RF harness has its own water temp. I assume the vehicle speed sensor is for the speedometer and covered by the RF harness and gauge. Oil pressure in RF has its own unit. Tacch not sure?

Thanks for the help