North American Turbocoupe Organization



Temp gauge inaccurate
alanjlambert1472 Offline
Member
#1
I was poking through the tech articles and saw something about an IVR problem causing the gauges to spike and stay there sometimes..

In my case, the temp gauge does it a lot, while the rest seem to work just fine (oil pressure looked a little higher than normal tonight, but still within range and I attributed it to colder running temps since it cooled off a bit since yesterday). Would a problem with this unit only cause ONE gauge to go nuts? I know the motor isn't overheating, since as a precaution I pulled over and though the gauge was above the red area the radiator cap was almost cold, and the rest of the cooling system was only warm.

Thoughts? Easy fixes? I used to have gauge fluctuation problems in my Shelby but a quick squeeze of the pliers on the oil pressure connector solved that one for good.

Final footnote: it seems (in the past week) to only do this mostly when its running colder.. on those 90 degree days it was fine.
1986 Ford Thunderbird Turbo coupe
all stock, hacksaw muffler delete, 124k miles.

1985 Ford Thunderbird Elan 5.0, 172k miles, shift kit, true duals, stock otherwise. **SOLD**
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Timmay Offline
Senior Member
#2
my gauge does the same thing and my motor is never overheating i think its just the sending units bad but havent messed with it.
1988 Turbocoupe- RIP in a place without rust!
1978 Mercury Bobcat super clean-2.3T, t5 trans, 8.8 rear 3.73 gears 31 spline axles,255 walboro in-line,MBC,3 inch exhaust,4 wheel disc brakes,5 lug
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Jeff K Offline
Administrator
#3
Sticking IVR will cause all 3 gauges to spike at the same time. The spike is quite rapid.... all 3 max out in maybe 5 to 10 seconds, and then all 3 recover at the same time to the "correct" reading. If just 1 gauge is spiking, the problem isnt the IVR.

Could be the temp sender is starting to develop an internal short. Poor electrical connection at the sender or between sender and gauge will result in the gauge dropping way low, not spiking high.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
11 Crown Vic Interceptor
14 Toyota Camry (wifes car)
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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alanjlambert1472 Offline
Member
#4
So I'm probably better off just replacing the sender then? As a footnote, when I was driving along all three gauges seemed to return to a semi-normal level.. but the temp is still the most erratic of the three.
1986 Ford Thunderbird Turbo coupe
all stock, hacksaw muffler delete, 124k miles.

1985 Ford Thunderbird Elan 5.0, 172k miles, shift kit, true duals, stock otherwise. **SOLD**
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junkedturbo Offline
Senior Member
#5
Pull out the water temp sensor and test it to see if its working right, the problem maybe the wire or even the guage itself. My fuel guage always use to act up even with a new sender unit.

Just be sure though you pull out the water temp sensor on the drivers side of the block, not the water temp sensor in the lower intake.
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alanjlambert1472 Offline
Member
#6
So I believe it might be the IVR and the sender, to some extent. See what this sounds like:

All 3 gauges (oil pressure, fuel, coolant temp) seem to read higher on the scale when its cooler outside. The warmer the ambient temp (say, 85 at high noon), the lower all 3 read, with the temp gauge still sometimes shooting up.

When its a cool night the temp gauge will frequently shoot up past H within 2-3 miles of driving... then it seems to creep downward if the car isn't moving..

Still I check, and the motor is fine under all circumstances.

Is it worth trying to f around with the IVR and senders or should I just do the AutoMeter treatment like I was planning?
1986 Ford Thunderbird Turbo coupe
all stock, hacksaw muffler delete, 124k miles.

1985 Ford Thunderbird Elan 5.0, 172k miles, shift kit, true duals, stock otherwise. **SOLD**
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