Chrysler Repair: Fuel Economy

Question
QUESTION: Hello Roland,
This is regarding my 2006 Chrysler T&C Touring van 3.8L Mileage 113,900.
I am getting very poor mileage. Our Wi weather is starting out very cold.
I'm getting 9 to 11 mpg city driving. Scan tool shows fuel trim ect. all within specs.
I have replaced plugs, thermostat, radiator cap, both oxy. sensors. Cleaned throttle plate, put injector cleaner in tank.
Question about cooling system, it takes for ever to get to operating temp. In using scan tool, running at higher idle, it will reach 220 degrees plus for the fans to come on, running about a 1/2 hr. At this time the temp. gauge is almost 1/2, otherwise at highway speed the gauge is generally just past the 1/4 mark. Will get to about the half mark. I can run all over town, come home and take the radiator cap off, no pressure.
I have a special funnel I attach to the radiator. I ran engine trying to remove any trapped air.
A trip out of town, 200 mi. I got 22 mpg.
Any ideas ?

Thanks for your help,
GCM

ANSWER: Hi Gary,
The temp gauge doesn't seem too far out of position given the weather, but it might be inaccurate. What is the nominal temp setting of your new thermostat? If it is much below 195 you might try replacing it with a 195.
Two other possibilities: are the tire pressures at the recommended levels, and have you touched all 4 wheels after having driven it to test whether you might have a dragging brake? Any increase in rolling resistance could pull down the mileage.
Absent a fault code I don't have any other suggestions. I will be curious to know what you learn.
Please read the PS below and respond.
Thanks,
Roland

---------- FOLLOW-UP ----------

QUESTION: Hi Roland,
Tire pressure is good. Ran on highway today about 10 mi. Checked brake rotor temp, all about 66 degrees. Outside temp 12. Used scan tool. Engine temp was about 170. Stat replaced again,195 HD Stant. Before had Chrys. 195 OEM replacement. Running in driveway at high idle, it took about 1/2 hr to get to 221 deg.temp gauge just below half. Rad. fans came on.
Why should it take so long to get to this temp ?
Also noticed the downstream 02 was running on the rich side while on highway. Only changes on accel. This is a new Bosch sensor.
I know cold weather will effect this, but why does it take so long to get to the 195 and above temp ?
I only had this veh. about 6 wks. I am ready to dump it !
Filled with gas yesterday, drove 158 in town miles. I got 9.4 mpg.
Any other ideas ?

Thanks for your time !!!

GCM

Answer
Hi Gary,
I have the manual for the '06 (and similarly for the earlier models of that engine). I suspect that the thermostat is not seated properly in the coolant outlet connector (the part to which the hose is attached) because of the presence of some metal "staking" ears that were used on the original installation of the thermostat in that housing at the factory. Once you remove and replace the thermostat if you don't remove the metal bulges (3) then the replacement thermostat doesn't seat tightly and can allow coolant to leak around the thermostat. I can copy the page from the manual that shows the details and attach it to an email I will send to you directly.
If you would like that please tell me your email address but don't use the @ symbol when you tell me, instead us "at" or the website will erase the address from your follow-up question. If you would like to keep it private, then click on the private box, and if that is not present then send a new question where you will definitely find a 'private' box to check.
Let us see whether that would improve things. You might also check out the wiring on the downstrean oxygen sensor as those are fragile and one may shorted to another or to ground. I can tell you the pin number connections if you want to verify that as well.
Roland