Whats up Dodge Friends,

I have a 2000 Dodge Durango 4.7 I bought used a few months ago. When I bought the truck it was getting 12.5 mpg and had check engine light on. I got the codes for it and it said "second engine coil" and "evap canister" if I can remember correctly. So I changed all the spark plugs and then changed second engine coil and replaced the map sensor and none of this has helped. I get 11.1 mpg and when its cold (I live in Duluth,MN) when I start it and get to a red light, it will shut off but then it starts right back up. I'm thinking it could be an o2 sensor but not sure if its upstream or downstream. Someone help me out if you can. Thanks and I appreciate any suggestions......

 

Does it sputter then shut off or just die?

Most likely if it's O2 sensor related, it will be the upstream (pre-CAT) as all the downstream does it monitor CAT performance.

 

It just dies. This usually happens early morning. And never happens more than twice in a day. I had a vacumn test done and there are no leaks detected. So I'm really focusing on the o2 sensors.

 

O2 sensors will give you the bad gas mileage. Your battery is probably the problem with it shutting off if it just dies since the alternator isn't putting out enough at idle and your battery can't put out enough volts either when it's cold or not charged yet by the alternator because most of it's reserve capacity is gone, so the PCM kills the engine.

 

Yep battery is the primary suspect in this one! All the problems you discuss are battery related.

 

Is it possible that the o2 sensor has anything to do with it shutting off. Believe it or not, my main concern is the low mpg and check engine light

 

Yeah more than likely the weak battery is giving you a weak spark, and wasting fuel to over compensate for the weak spark.

There also is a chance O2 sensors are fine.

 

Then where would the check engine light come from? i appreciate the help so far

 

If there was any problems with your O2 sensors, the MIL codes (check engine light codes) will deffinetly let you know about it. I believe since you have a newer model D you can do the key trick to display your ODB codes if you don't have a scanner.

 

Whats the code your gettin?