coolant temp reading-PL or gauge?

[ShaunKris]

Between the coolant temp in Powerlogger vs the Autometer gauge, there is about a 15 degree difference. Which do you think is more trustworthy? The Autometer gauge/sending unit is of unknown age, FWIW. It's an electric gauge.

edit* The reading in powerlogger is the higher one. Gauge shows about 170ish warmed up. PL shows about 185-190

Just curious since I'm wiring in a gauge myself, are both ecm/PL and gauge hooked up to the same sensor?

 

[6gunn]

Just curious since I'm wiring in a gauge myself, are both ecm/PL and gauge hooked up to the same sensor?

Nope, the gauge has its own sending unit. I think the ECM and PL take their reading from the CTS on the front of the intake manifold.

 

[ShaunKris]

Nope, the gauge has its own sending unit. I think the ECM and PL take their reading from the CTS on the front of the intake manifold.

ok, there are two sensors on the front of the hot-air manifold one mounted vertically and one horizontally facing forward. the sensor switch I got from Coldcase is mounted in the front horozontally, I hooked up my relay and over ride switch to that one because it is an on at 180degrees, there is no gradual voltage change it is either one or off, so it turns my fans on automatically at 180 degrees. The other is a sender I believe, I spliced into it to experiment and now my gauge reads but my scanmaster does not, it just stays at 112 degrees. soo.. I think it is going to need it's own sender somewhere or I'll need to get voltage info from the ECM. Can you even do that on an 87 ecm?

 

[6gunn]

Not an expert in this arena(wiring) but it almost sounds like there is some cross talk when trying to tap into the factory sending unit. I think it'd be better to leave the wiring for the CTS alone, and just use the switch that you got from Coldcase. It turns the fans on at 180, so it sounds like it's operating properly.

 

[ShaunKris]

Not an expert in this arena(wiring) but it almost sounds like there is some cross talk when trying to tap into the factory sending unit. I think it'd be better to leave the wiring for the CTS alone, and just use the switch that you got from Coldcase. It turns the fans on at 180, so it sounds like it's operating properly.

Agreed, I appreciate your honesty, and thank-you for chimming in on this. I believe you are right, I guess my only option is to add another sensor for the gauge or just get off my butt and install the new ECUGN..lol. I'm no expert either so I always appreciate when somebody wants to chim in and problem solve with me.

 

[salvageV6]

You can plumb a T or Y into the front or top of the intake and run 2 sensors.
If the car has a 2 wire factory sender that goes to the ecm you can't splice into those wires and expect it to work right.
3/8" NPT threads are in the block, you might have to bleed the two senders you install outside of the water flow but they will read within 5 degrees of the block once the water goes into the external plumbing.
You have to measure everything carefully so you have room to spin the senders on and install the brass fitting.
Here's the name you can search for for the street T brass fitting, the one listed is expensive but well made.
Home depot may have something cheaper.

Anderson Metals-06127-06 Brass Pipe Fitting, Barstock Street Tee, 3/8" Female Pipe x 3/8" Male Pipe x 3/8" Female Pipe​

This of course assumes the aftermarket senders are 3/8" NPT which they most likely are if they fit the block hole.

 

[ShaunKris]

You can plumb a T or Y into the front or top of the intake and run 2 sensors.
If the car has a 2 wire factory sender that goes to the ecm you can't splice into those wires and expect it to work right.
3/8" NPT threads are in the block, you might have to bleed the two senders you install outside of the water flow but they will read within 5 degrees of the block once the water goes into the external plumbing.
You have to measure everything carefully so you have room to spin the senders on and install the brass fitting.
Here's the name you can search for for the street T brass fitting, the one listed is expensive but well made.
Home depot may have something cheaper.

Anderson Metals-06127-06 Brass Pipe Fitting, Barstock Street Tee, 3/8" Female Pipe x 3/8" Male Pipe x 3/8" Female Pipe​

This of course assumes the aftermarket senders are 3/8" NPT which they most likely are if they fit the block hole.

Oh awesome! Thank-you! You are right it is tight it will have to be measured and I will definitely look into this, and yes they are 3/8".

 

[Chuck Leeper]

If the car has a 2 wire factory sender that goes to the ecm you can't splice into those wires and expect it to work right.

^^ this! No double ups!