Am I the only one that saw a drop?

Changed 4 out of the 8 cyliners spark plugs on my 5.7L, couldn't reach the other 4 because my tools suck. Also changed the rear end to RP 75-140. Drove it this weekend on the hiway for 50 miles --> 12.5 mpg, down from about 13.5-14.5. This is hand calculated. I'll do some more driving this week and I'm just hoping this drop this weekend was from a strong headwind.

 

Just tuned up, and had to replace the PCM (long story) and still getting 14.1, which is down from 14.5 before the tuneup. I hope he didn't accidentally hit the metric button on his trip computer! I was getting 17 till I switched to US. Do you guys reset the trip computer after every fillup? Also, how big is the tank on an '04 QC 4x4?

 

I never use the overhead console for fuel mileage since it's just a guess at what the truck might be getting. You can thank dodge for not putting in the correct sensor.

 

Doing a search looks like your tank is 26 gallons.

 

All you guys mpg look good to me. lol.

 

^^^^+1 ME TOO!! I would love to be getting 14!! I cant get much over 11 driving like my grandfather!! If I get on it it drops to about 10!




but dam those 35's look good LOL

 

Just a tip. You guys that are changing your plugs and seeing a drop, Check the gap of the new plugs before you put them in. About 60 percent of the new plugs we put in are not gapped properly.

Also you need to change them all, Not just 4. Otherwise you get half your cylinders with a weaker fire pattern that the others and also causes uneven wear on your plugs.

 

You need to change all 16 plugs. If your PCM is seeing different spark conditions it will go with the worst and use that for all of its calculations. Also what plugs are you using. I am using regular champions. A buddy of mine put some expensive plugs in his hemi and the mileage went down, then he put in the cheap champions and it went up.

I am just going off of the overhead for now, when I fill it up I hand calculate, but I have the optional 35 gallon tank so it takes a little while.

 

What do you get out of those SRT 10s?

 

man would i love to have one of those SRT's i love them things, i have a knock off srt lol, i see a 13-14 average around town and about 16 on the highway wish i could get more only have 26000 miles on her