99 GT Troubles

Hi, I have a 99 Gt 3.4L and as I was driving it down the interstate today I started noticing that the RPMs would randomly go up 1-2 hundred RPM. Also about every other time the RPMs fluctuated the temp. gauge would drop down to 0 and then go back up to normal, the bumpier the road, and the slower I went the more fluctuations. My worst fear is that the problem is in the transmission, could the temp. gauge be sending false signals and messing with the RPMs? The only thing that makes me think that is the fact that the RPMs when they go up are at about the same level as it would be if the car was cold. Hope this makes sence to someone, please help.

Sounds to me like a bad connection somewhere.

Did the engine run/act funny when the gauges jumped around ?

other then the RPM jump no.

do you think the two issures are related? I'm going to go ahead and try changing out the coolent Temp. sensor and see if that has any effect.

haha, the two are not related. The RPM jump while driving is most likely the torque converter unlocking when there a light change in engine load.

Well then what is causing the temp. gauge fluctuation?

I would inspect the wiring to/from the temp sensor. They can get damaged. Or if the plug-in is soaked in oil that can also cause intermitant signals from/to the PCM.

But I have heard a few people having thier instrument clusters going on the fritz and needing a replacement.
Kinda like the stock radios LED displays going haywire. :screwy: