09 tc 3.8, runs great but gets 13/14 mpg after plugs and wires. Does anyone have what my specs should be w scan tool live date that I might identify if there is a sensor or something throwing fuel economy off? No check light, smoke oil leaks etc...

 

how are you gauging you mpg? your math or using the onboard computer?

 

260 per tank before fill up when needle is resting at E. Reset average mpg at each fill up

 

Anyone know a reference to what my values should be for o2 sensors, map sensor and fuel trims when warned up?

 

Hi knitefall. I read something similar on another forum a while back and it appeared to be and issue with the 5th gen T&C. However, several people had reported that turning off the ESP solved the problem, although no one ever reported finding an answer as-to why the ESP began causing the problem to begin with!

 

We tried that, no gain. I will bite the bullet and perhaps the Lord will have favor on our gas money after changing 02 sensors. The stealer is a rip off and does not know. It's there any other place I could go to ask a technician?

 

The easiest answer would be the Coolant Temperature sensor telling ECU engine is continually cold and needs a rich mixture. Your engine is running ok with no hunting, spluttering, missing a beat I take it. 02 sensor maybe covering it up.

 

You're right, sometimes it's the culprit. On the scan tool it's operation is where it should be. I'll visit after i look w the New o2s

 

is this city driving? ac on ac off? as for the sensors i highly doubt they are any culprit.
Why well because there is this nice long mathematical equation that is used each mili second of fuel and spark. The software guys use the input from each of the sensors to make this mili second timing aka how much time to leave the fuel injector open and how long to spark the plugs. If infact there was a songle sensor issue like a map or 02 the computer would be able to pick up on it The map is checked by the baro sensor the o2s are checked by each of there own down stream 02. Coolant temp unless its drastic say 50 degrees it wont make any difference. Outside ait temp makes a difference but you sould see that with a check engine light code. What im basicly saying is if one of the sensor is out of wack the other would would pick up on it and a code would be set. I would looking into driving habits. Tires, Ride the brake much, Load down the van with stuff weight kids ect. Then ac or defrost on they are the big factors. I have an older NS weights about 1000 lbs less then yous has 240k on her and I get 16 mpg around city.

 

Thanks for the input. The coolant temp sen is reading accurate but I did find the o2 upstream to be lazy at times. When I pulled the heads, number 4 exhaust was half shut w hard carbon. See, we just bought the thing and had to change the cat. I also found the tops of the pistons thick w carbon but the heads were clean. But I seen no other restrictions.

Plus, others w the same model state they get around 16 in town. This thing gets 13 when calculated. W/o a.c. no ethanol gas, no trac lights, eng light etc. There has got to be something else I can check that has to be the culprit.