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cold temperature gauge

10-22-2009, 09:47 AM
I've been having a problem with my 95 integra GS-R running cold(at least, I think it is). I've searched the forums but can't seem to find a solution.
temp gauge at or near C
luke warm, not hot, heat from vents
no vtec
temp needle falls when heat turned on
temp needle falls when cruising on highway
car seems to idle normally(~900rpm) after several minutes
worse MPGs on last fillup(usually 30+, now 26)
fan will turn on with the A/C
If I sit and hold the rpms at about 3K for maybe 10 mins the needle will at most move up to about 1/8 and the fans will come on briefly. As soon as I lift off the pedal the fans go off and needle returns to C and never climbs again.

replaced thermostat(twice)
repaced temperature sensor

Everyone I've asked seems to think that I need a new thermostat, but I've replaced that twice. I think the gauge is working since it will moves and doesn't simple sit on C. Also, I don't get any heat.

Any ideas? Any help would be greatly appreciated.


12-09-2009, 08:45 PM
that is wierd. If you got a couple of thermostats laying around I guess you could try and get one closed shut (wont open) and stick it in there and see if you can get any heat.

12-10-2009, 06:41 AM

The problem was the temperature gauge sending unit. I still can't explain the MPG drop. Maybe I drove it harder than I remember during that tank.

12-11-2009, 03:08 PM
that is really wierd, I would think that it would still get up to running temp and all, the thermostat should work independantly from the other systems I would think.

Good to hear you are rockin now.

08-31-2011, 12:19 PM
This is a late post but I have the same problem with a too-cold coolant temperature.

The reason you were getting worse gas mileage is that the transmission's torque converter won't lock up until the engine temperature is high enough according to the ECM. So, if it is falsely reading too low it will not lock up in top gear, causing the engine/tranny to slip at highway speeds.

When my car's ('99 Intergra LS) temp gauge gets to about 1/3 above Cold I can drive at 70 mph and the engine will be turning around 2800 RPM. I know the TC locks up because if I try to accelerate, the RPMs rise directly with the car's speed.

But when the engine cools off to about 1/4 above Cold, I'll be going 70 mph @ 3000 RPM. Here when I accelerate, the RPMs rise and then the car's speed increases. This tells me the TC is not locked up.

At what temperature the TC is allowed to lock up I won't know until I test with my OBD scanner.

The TC is kicking out when the coolant temp drops below 168 degrees. I checked the temp sensor with an infrared thermometer pointed where it is screwed in and the OBD data and reading matched. So taking into effect surface cooling, the sensor is at least within reason. This leads me to believe that the thermostat is stuck open. If it were closing properly, it wouldn't let the coolant get so cold when I'm driving fast.

09-12-2011, 11:28 AM
Sure enough, it was the thermostat. Pulled the old one out and the center part was warped or bent such that it couldn't close completely. It was also marked 76C (170F), lower than OEM. Guess the last owner thought that a lower temp would be better...uh, not quite.

With the new t-stat, engine runs at one temp after warm up and the TC functions normally.

[UPDATE] I swapped the OEM temp with a new 170F thermostat. Engine runs a bit cooler now but still plenty high enough to allow TC lockup.

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