Coolant temp gauge dances

**2kbluws6** · 09-18-2006, 06:49 PM

ok, now i know this may sound a lill perverted and maybe even a lil messed up but my coolant temp gauge puts on a show for me when she is cold of even sometimes when it thinks i feel lonely.

For instance i will start the car in the morning, any weather condition, and start to drive. as the gauge moves up all of a sudden it will drop to nothing and the car jerks. then moments later it will go back up to the temp. and it will do this usually all the way up till the car is warm.

It will also do this randomly after the car is all warmed up and i could be just cruising down the road al low rpms or even when i beat on it...and it is just random. but when it does act up, the engine will like fall off and then come back.

what i have done is replaced the temp sender in the drivers head, checked for codes, and also started the car with the scanner hooked up.

still does it with new sensor, no codes and it doesnt "act up" in the scanner readings when it actually does act up.

Im sure it also has something to do with it...sometimes when i drive and park it after it is all warmed up, i run into a store or something and come back out the car will not start...extended crank. to get it started all you have to do is start it with the foot on the floor.... it starts and smells rich as all hell.

i am a educated mekinik...but i have not put much time into it other then the "what i thought" was obvious things listed.

List of mods below in sig

**2001NBMZ28** · 09-18-2006, 07:28 PM

Since you replaced the ECT sensor, and if there's nothing wrong with the wiring/connector, my next guess is a PCM problem. Too bad it's not throwing a code, would be much easier to diagnose. The way I understand it the gauge gets input from the ECT, thru the wires, thru the PCM, then to the gauge.

**2kbluws6** · 09-18-2006, 07:54 PM

I was thinking along those lines as well. but i really didnt want to think that negative...but it does also validate another problrm that i have been having with the ses light, which is totally not related to the coolant temp problem. the ses light throws randomly in any driving or weather condition for banks running lean. to try to fix that i did an unecassacary une up with msd stuff and fuel sys cleaner, and a fuel filter, and air filter. and it still comes and goes. it even clears itself usually within a day or two. im lucky if i drive 30 miles a day normally.

Tim

**2001NBMZ28** · 09-18-2006, 08:52 PM

Have you looked at the PCM connectors? Disconnect the neg battery cable, loosen the bolts, pull them and look for any burnt pins or evidence of any possible water intrusion. Something easy to try...

**jimmyblue** · 09-19-2006, 05:42 AM

Check the ECT sensor connector too, it can get loose or
crusty and flake out the signal. Then the ECT fuel & spark
adders drive the engine crazy.

**Bryan** · 12-12-2006, 06:05 PM

Did you find what the problem was? My temp gauge started doing the same thing this weekend and my car has developed an intermittent miss.

Thanks!

**2001NBMZ28** · 12-12-2006, 07:13 PM

Have you already checked the ECT sensor plug/wiring?

**2kbluws6** · 12-12-2006, 07:49 PM

i have. i kinda gave up on it for now...there is snow on the ground here. but i have put some connector stabilant on the connector, cleaned the connector, replaced the sensor and even checked the connection at the pcm.

**Bryan** · 12-13-2006, 04:58 PM

Mine was missing so bad this morning that I didn't think I would make it out of the neighborhood

and then it only missed one time driving 40 minutes home from work even with the temp gauge going crazy.

I'm hoping to get it fixed next week, if so I'll let you know what it was.

**2001NBMZ28** · 12-13-2006, 06:07 PM

It would be interesting to see what the actual ECT/PCM is reading when the gauge is going nuts on a scanner.

**Bryan** · 01-13-2007, 06:03 AM

Sorry for the delay in responding but my car is fixed. My problem was a cracked temperature sensor. I took it too a chevy garage, they replaced it and now all is good except I'm $100 poorer.