ZR-1 Net Registry Forums - View Single Post

csavaglio · 11-19-2013

Ok, problem solved.

Here's what I found out:

The factory gauge is, as was theorized by another poster, 0-100 ohms.
The FSM, to test, says to apply 0 ohms and it should peg the gauge to 0 psi, 100 ohms pegs it to full high. It says 40 ohms should read around 30psi on the gauge.

I even ohmed out the connector to make sure it wasn't giving a bad connection and adding extra resistance (which would make the gauge read high).

The Wells made senders I received (Valucraft and Duralast) both were producing around 15-20 ohms too much, making the gauge read about 20-30 psi too high. At a cold idle, the car was actually making 65 psi and the Valucraft sender was showing nearly 110 ohms, pegging the gauge out at full high. So, the specs that were posted by another forum member above that Wells published were not accurate to the sending units I received. If they were, my gauge would've functioned correctly.

I went down to Napa and the guy gave Echlin a call to find out what the ohm scale was for their sending unit. Basically, it was very similar to the numbers that Wells officially published. It's a 0-80 psi sender, with 80 coming in at something like 65-93 ohms.

In the parking lot, I put in the new Echlin sender, part number OP6677. I haven't ohmed it yet, but it works perfectly. At warm idle, the gauge reads about 1/4 from 0, which should correspond to the 20psi the car is actually making.

For the record, I also have a NOS Delco one coming, same part number as the one at Jerry's. If I feel up to it, I'll test it out and see what readings I get off of it.

Being that Wells produced both sending units that had identical calibration issues, I think that either they're calibrating them incorrect for our application or there was a bad batch of units. As I said, I have a Duralast/Wells sender in my LT4, and it works well, but does read a little low compared to the working factory one (that I busted putting the intake on....).

The Echlin one looked slightly different inside the connector and at the base of the body, so I don't think it was produced by Wells.

Hopefully all of this helps someone out there.

Thanks, everyone for the suggestions and help.

Chris

11-19-2013	#18
csavaglio Join Date: Oct 2013 Location: Colorado Springs, CO Posts: 160	Re: Oil Pressure Sender Ok, problem solved. Here's what I found out: The factory gauge is, as was theorized by another poster, 0-100 ohms. The FSM, to test, says to apply 0 ohms and it should peg the gauge to 0 psi, 100 ohms pegs it to full high. It says 40 ohms should read around 30psi on the gauge. I even ohmed out the connector to make sure it wasn't giving a bad connection and adding extra resistance (which would make the gauge read high). The Wells made senders I received (Valucraft and Duralast) both were producing around 15-20 ohms too much, making the gauge read about 20-30 psi too high. At a cold idle, the car was actually making 65 psi and the Valucraft sender was showing nearly 110 ohms, pegging the gauge out at full high. So, the specs that were posted by another forum member above that Wells published were not accurate to the sending units I received. If they were, my gauge would've functioned correctly. I went down to Napa and the guy gave Echlin a call to find out what the ohm scale was for their sending unit. Basically, it was very similar to the numbers that Wells officially published. It's a 0-80 psi sender, with 80 coming in at something like 65-93 ohms. In the parking lot, I put in the new Echlin sender, part number OP6677. I haven't ohmed it yet, but it works perfectly. At warm idle, the gauge reads about 1/4 from 0, which should correspond to the 20psi the car is actually making. For the record, I also have a NOS Delco one coming, same part number as the one at Jerry's. If I feel up to it, I'll test it out and see what readings I get off of it. Being that Wells produced both sending units that had identical calibration issues, I think that either they're calibrating them incorrect for our application or there was a bad batch of units. As I said, I have a Duralast/Wells sender in my LT4, and it works well, but does read a little low compared to the working factory one (that I busted putting the intake on....). The Echlin one looked slightly different inside the connector and at the base of the body, so I don't think it was produced by Wells. Hopefully all of this helps someone out there. Thanks, everyone for the suggestions and help. Chris