Temp gauge goes down when stepping on gas

[rms13Mike]

I know there has been threads about broken temp gauge but i can't seem to find the right one that matches my problem. My temp gauge read fine when idling but when i step on the gas at a stop and reach about 2500-3000 rpms, my temp gauges drops all the way down, and when im driving on the free way in 5th gear 80 mph it just stays down. what could be the problem? please help, im changing out my clutch fan to e-fans at the same time and i need my temp gauge to work right so i can tell if my e-fans are good enough. and does any one know what the wire that is bolted to the right of the temp sensor? mine is kind of loose and i was thinking maybe that is whats causing my temp gauge to drop.

sorry for the long explanation. thanks in advance!

[s13-t]

Does your heater work? Does it start pushing warm air pretty quickly after a cold start? Does the engine warm up to operating temp quickly or does it seem to take forever? Reason I ask is because the situation you describe matches a problem I had with an old honda. Turned out to be that my thermastat was stuck wide open. Thermostats are cheap so id say buy one, replace it and see if it fixes your problem. fixed mine.

[Bstrd240SX]

i second the themostat suggestion. sounds like its stuck in a position that allows about the right amount of coolant flow for the car to warm up when the water pump is spinning its slowest

[rms13Mike]

Does your heater work? Does it start pushing warm air pretty quickly after a cold start? Does the engine warm up to operating temp quickly or does it seem to take forever? Reason I ask is because the situation you describe matches a problem I had with an old honda. Turned out to be that my thermastat was stuck wide open. Thermostats are cheap so id say buy one, replace it and see if it fixes your problem. fixed mine.

i second the themostat suggestion. sounds like its stuck in a position that allows about the right amount of coolant flow for the car to warm up when the water pump is spinning its slowest

yeah my heater works fine, it melted the ice that was on my windsheild yesterday morningprobably 4 min after i started the car, it SEEMS like its taking just a little more than before but im not exactly sure. no offense but i just want to understand this better, how does the wide open thermostat cause my temp gauge to go down when i step on the gas?

[rms13Mike]

recently i help my friend jump his car and when i connected his battery to mine and started my car and revved it a little, my temp gauge stopped dropping when i revv pass 2800. could it be ground related that fixed it?

[Azrial]

Sounds to me like it's grounding somewhere. If your radiator hoses are getting hot etc like they should then the gauge is probably reading incorrectly because it's grounding out. Perhaps when you rev your engine it's rattling whatever wire is lose causing it to ground.

[Cone Junky]

The 2 pin water sender is for the ECU and the single pin sender next to it is for the gauge. I would try to tighten up that connection first. maybe the accell is just enough for it to wiggle and lose connection. If not, check all your grounds and wires for possible breaks (if it were a short to ground it would peg at full hot.)

[Bstrd240SX]

no offense but i just want to understand this better, how does the wide open thermostat cause my temp gauge to go down when i step on the gas?

a thermostat is a valve thats ment to keep the proper amount of heat in the engine

picture that your in the kitchen making a huge christmas dinner, its 30 outside, you want the kitchen to be 70 because thats a comfortable temp, but the oven / stove is making it 120 in the kitchen

so what do you do? you open a window just enough to make the room 70* for yourself, all is well and good ... this is your car idling

now a storm kicks up outside and the wind starts to blow hard, the room temp drops because you have way more airflow through the open window, this is what happens when you start to drive ... the coolants moving faster thru the engine so it doent get as warm anymore, just like the stove isnt cranking out enough heat to keep the air in the room warm anymore

make sense ?

[s13-t]

good analogy. I look at it like this- more rpms= faster the water pump spins= more coolant through wide open thermostat which cools down the engine. Not to hard to understand... no offense

[rms13Mike]

The 2 pin water sender is for the ECU and the single pin sender next to it is for the gauge. I would try to tighten up that connection first. maybe the accell is just enough for it to wiggle and lose connection. If not, check all your grounds and wires for possible breaks (if it were a short to ground it would peg at full hot.)

alright thanks, ill check it, do you happen to know where is the ground for the sensor? or any other ground/power places that relates to the temp sensor?

a thermostat is a valve thats ment to keep the proper amount of heat in the engine

picture that your in the kitchen making a huge christmas dinner, its 30 outside, you want the kitchen to be 70 because thats a comfortable temp, but the oven / stove is making it 120 in the kitchen

so what do you do? you open a window just enough to make the room 70* for yourself, all is well and good ... this is your car idling

now a storm kicks up outside and the wind starts to blow hard, the room temp drops because you have way more airflow through the open window, this is what happens when you start to drive ... the coolants moving faster thru the engine so it doent get as warm anymore, just like the stove isnt cranking out enough heat to keep the air in the room warm anymore

make sense ?

yea thanks i know what the thermostat does, i guess you thought that it goes down and stays there as if my water cooled down, i meant that it bounces when i step on the gas

heres a video to be more specific of what happens

http://www.youtube.com/watch?v=D79RUQIhHl8

[Bstrd240SX]

well then, i don't believe that's the fault of the thermostat, it fluctuates way to fast. if it was the thermostat it would drop a bit slower and then take a WHOLE bunch longer to come back up

and i aqppologize for the explination, at the time it sounded like what you were asking, its always hard to know what people do or dont know about cars via the internet

[H8tred]

Not saying that this is your problem, but air in the coolant passages can do this as well. I just put my aluminum radiator in due to the stocker taking a crap on my finally. I cut the overflow hose while routing it past the new rad and didn't know it. It was enough to allow coolant to get pushed out and air to make it's way back in.

Just another place to check.

[rms13Mike]

Not saying that this is your problem, but air in the coolant passages can do this as well. I just put my aluminum radiator in due to the stocker taking a crap on my finally. I cut the overflow hose while routing it past the new rad and didn't know it. It was enough to allow coolant to get pushed out and air to make it's way back in.

Just another place to check.

ooh i see, so maybe bleeding the coolant could work. taking the radiator cap and running it till bubbles stop popping out?

[H8tred]

You have to get the front end off the ground. I usually just find a hill, and squeeze the upper radiator hose.

[1KleenS13]

The 2 pin water sender is for the ECU and the single pin sender next to it is for the gauge. I would try to tighten up that connection first. maybe the accell is just enough for it to wiggle and lose connection. If not, check all your grounds and wires for possible breaks (if it were a short to ground it would peg at full hot.)

I just went through this the other night. The terminal at the 1 wire sensor was loose. I just took the wire off and tried putting a little solder on the sensor where the terminal comes out. Fixed it. I also got some electrical cleaner and cleaned both ECU temp sensor, and Dash sensor connections. Its worked fine for the last week.

[rms13Mike]

thanks its fixed now, i dont really know what i did to fix it, i fix the wiggling metal beside the temp sensor and tried cleaning the sensor wiggled it around a little. then pushed in the wires on the ECU, i wasn't really able to check if there were loose wires. and at the same time just finished putting in my e fans. everything's good so far. thanks everyone!