Changed the plugs on my 2005 Durango Hemi at 55000 miles. Prior to change I was getting 15 to 16 MPG around town and 18+ on the road...after change the mileage has dropped to 11 to 12 around town.

What should I check ??

Also have noticed occassional lugging when light acceeleration ..

I'm thinking maybe a plug wire connection got damaged or should I look at EGR, Dist Cap,

Is there any diagnostic or test to figure this out?

 

Are you using champion plug? The hemi's don't have a dist cap, they have coil packs and wires. And sure you could have a bad wire or two.

 

Did you get 16 spark plugs?

http://www.championsparkplugs.com/re...p?aaia=1435909

 

check for moisture in cap. if you have a cap. i all ways plug the vent in mopar caps. with JB weld. took me 5 years to learn that. changing a cap every fall.

 

Nofear:

While I have touched 18 mpg on the hwy a few times, the norm is 16-17.
I would love to see 15 in town, but it does not happen and I am a very easy driver.

10-12 is the in town norm for me. 330 horsepower moving 5200 pounds around does take some petrol!

Have you done the key dance to see if there are any codes stored in the system? If no codes are there and it is running fine, I say you are good to go.

The mileage displayed on the overhead console is not accurate. Several fill ups over time divided by the mileage driven is the best way.

Don