Wierd engine temp problem

[bellman3021]

Really strange problem. I have a 2006 sxt with cold air intake and I'm using the 89 oct predator tune. My engine temp gauage needle will run just under the middle line when idle or stopped. If I drive on the highway it falls to just above the first line. The heater is throwing off hot air though. I plugged the predator in and the ect temps
during highway driving are hovering at 128.
The theromstat and temp sensor were just replaced with the same results. The air temperture round here has been in the high 20's. Eventually the P0128 error gets tripped. I also notice when the car downshifts at wot a puff of brown smoke blows out the back. I don't baby the car can't imagine I'm gettng this much carbon build up... I'm lost at this point and don't know what to try???

[Hemi31]

you didn't put teflon tape on the sensor threads did you?

I don't have the manual in front of me but I would find the spec for the ohm reading across the pins on the sensor and test that and then trace your wiring and look and see if anyone was chewing on it.

[Zombifyd]

I get the same thing when winter hits here my temp gauge drops to bottom line and the CEL comes on with that code, and then I loose heat. I heard it has something to do with the thermostat, that you need a higher temp one. I still have yet to look deeper into the problem.

[Toronto Charger]

Get it checked out at the dealership for warranty work! Reverse your Pred mod first... there was another thread where a guy had it run too hot for too long due to his fan failing and they voided the engine warranty for neglect... let 'em have a peek but be clear that you don't wanna pay if warranty will not cover it.

Better safe than sorry...

[Mics Mag]

Hmmm, hope its not a head gasket leak. Is your coolant level going down? You can have a pressure test done on the system to check.

[ToddStone]

Did you try to reset the tune to it's natural state and then retune it? That might be the issue and then pull Fuse 11 on the fuse box. See if that works.

[Clayman]

This is common here up in Canada, and mine does the same thing, I don't drive in the wnter so I don't care. But it is your thmerostat is sticking open, I change lots to t-stats for this problem.