The pic below is not my dash, I'm posting it to show the temp gauge only (mine is Metric)

My GT's Temp Gauge was showing a normal engine temp as the gauge in the pic below.
It looked wrong to me - too low, and would go even lower (almost to the 100F) when the fan kicked in.
It sure looked like I had a stuck open thermostat - but it's a brand new Stant (and has NOT collapsed).

Scanning with TunerPro showed the engine to be fairly steady at 185F (85C).
That's exactly where I'd expect it to be as I have a 180F thermostat and Dickman's 210on/185off fan switch.
I used a 55 ohms resister to check the gauge and it peaked at the top of the gauge as it should.

So I replaced the sender with a new Standard Motor Products PN TS168T sending unit.
Once I did that, "normal" operating temp on the gauge was at the 220F mark (and sometimes higher)!!
What I'd expect is the needle around the 2/3rds mark between mid-point (160F?) and the 220F mark.

I figured I got a bum sending unit, so I replaced it again with a new Borg Warner (BWD) PN WT414
With this sending unit, I'm back to what the original sender was showing - in the bottom 3rd of the gauge. WTF??

What are you guys seeing on your temp gauge?? (and what thermostat do you have)

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Calgary time/temp

3.4L Supercharged 87 GT Click me
Super Duty 4 Indy #163 Click me

Im not sure about the V6, but on the Duke, there are 3 different temp sensors. 1 for the guage, 1 for the ECU, and 1 for the radiator fan, so the one for the ECU, could be working fine while the other is toast.

quote Originally posted by edfiero: Im not sure about the V6, but on the Duke, there are 3 different temp sensors. 1 for the guage, 1 for the ECU, and 1 for the radiator fan, so the one for the ECU, could be working fine while the other is toast.

I got the sensors figured out as to what does what.
The ECU sensor is also new. Reads exactly the same 185F (85C) as the one I took out.

But 2 NEW senders for the temp gauge give me drastically different readings.
One is showing too low (under 150F) and one is showing too high (220F) - in my opinion.

Neither puts the gauge at around 180F - the actual engine temperature.

[This message has been edited by fierosound (edited 04-28-2015).]

You should be able to measure the resistance of the gauge sensors to get an idea of what's happening. Knowing that will get you pointed in the right direction.

quote Originally posted by thesameguy: You should be able to measure the resistance of the gauge sensors to get an idea of what's happening. Knowing that will get you pointed in the right direction.

Please explain. Are you suggesting both new senders are bad?

[This message has been edited by fierosound (edited 04-28-2015).]

quote Originally posted by thesameguy: You should be able to measure the resistance of the gauge sensors to get an idea of what's happening.

Did this. It's 60F and I measured both sensors (engine is at ambient temp too).

The units will show lower resistance at higher engine temperatures. Should be 1365 ohms at 100F and 55 ohms at 260F

The Borg Warner sending unit in car is 2800 ohms at 60F. (this shows 20F too low on gauge at engine temp)
The Standard Motor Products one shows 4130 ohms at 60F. (this shows 20F too high on gauge at engine temp)

So they are calibrated differently, and both are wrong.
Maybe I need the Delphi unit? PN is TS10051 (maybe it's calibrated better?)

The sending unit appear to have an adjusting screw, but can't be turned.
This is probably used for calibration when the unit is assembled, then locked in place.

[This message has been edited by fierosound (edited 06-08-2015).]

Based on the 1365 @ 100 and 55 @ 260, 180 would be 655ohms. Why don't you put a 655 ohm in the circuit and verify the gauge is correct.

It would also not be to hard would be too bad to check the resistance at the 60 which would be about 1640 ohms and 212 which would be about 410 ohms.

Has the temperature gauge fix been done on the gauge? When you start the car it does a bulb check and the Fiero are wired you incorrectly and is applies full voltage to the gauge and not the bulb. Over time it can move the needle to cooler side. In my case the needle fell off. There are 2 ways to correct it. One way is to rewire the instrument pod, or in my case I just disconnected the lead in the steering column at ignition switch and insulated it.

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88 GT 5 Speed Black with gray interior
3800 SCII Swap Complete.
Paint Complete
Detailing in Progress

IT RUNS!!
IT'S QUICK!!

"Real integrity is doing the right thing, knowing that nobody's going to know whether you did it or not."

Never trust factory gauges.

quote Originally posted by tebailey: Never trust factory gauges.

All you can hope for is that the idiot light comes on when it should...

quote Originally posted by ILVMYGT: Has the temperature gauge fix been done on the gauge? One way is to rewire the instrument pod, ...

Did the temperature gauge "fix" years ago. I rewired the gauge at the cluster.
Details for those who don't know about this.http://www.fierosails.com/tempgage.html

Unfortunately, the gauge sender is not linear, so it appears you can never get it correct.

[This message has been edited by fierosound (edited 06-08-2015).]