I put the plugs my underhood sticker said to use. Champion RC12MCC4 and checked each plug as i gapped them to .040. The old plugs were most likely the original plugs and worn down to between .060 to .070.

 

My mileage seems to be getting a little better after I did a complete service. Is it possible that the trucks computer would have to get used to the heavier new tires vs. the old bald ones the would've been lighter?

 

well you also went up to a bigger tire you said, that will hurt your gas mileage, and it will throw off your trip meter so your hand calced number will be off, since the trip meter reads lower than the actual distance ( this is unless you had the computer reprogrammed for it)

 

Also, you had bald tires that cut through the air. Now you have a thick tread and that cups the air. This can cause a slight decrease in fuel mileage not to mention the height differences and gearing that you might have.


I lost 2.5 MPG's when I went to BFG KO tires on my old durango.


Also a PCM reset is needed after you install plugs or any other induction or emissions work. If you didn't reset the PCM it can cause a large reduction as the PCM is trying to run the old way.

 

I can see how the tires could do that, but I didn't think of that! How do I reset the pcm? Is that something I can do, or do I have to go to the dealer?
But my truck seems to be getting better mpgs. I have been averaging about 15 this week.

 

take off the battery and hold the key to start for 30 seconds, put battery back on

btw take off negative terminal only

 

Here "again" is the way at the top of the page. https://dodgeforum.com/forum/1st-gen...ine-light.html


But sharps nailed it.

 

Thanks guys, I will do that in the morn. You have been a BIG help to me! I have about a 95 mile drive to go to my fathers house on sat.

 

Perfect!

 

Hydra, I reset the pcm yesterday morn before I made the trip, fill my tank, and went to my fathers then stayed the night mothers and there was a huge difference in mpgs. I went about 130 miles and the guage hasn't made it to the 3/4 mark yet!!!