I am new to the site but in the past couple of months my truck, which has 87000miles on ithas lost about 3-5 mpg on both highway and city driving, I stay off the pedal and have just cleaned the TB on it and going to change the PCV valve at suggestions from this site, cleaning the TB was easy. I have noticed that it did get about 1-2 more mpg but looking to get it back to where it was.

I am also running a K&N and I have seen mixed reviews on this site about that....i do keep it clean. when i was cleaning the TB i did notice oil residue and was wondering if that was the K&N or was that motor oil? in the tube conecting the air box and the box to the TB i didnt notice any oil residue, and that would only have to be from the ail filter is there was.

Since i have had the truck i have not change the spark plugs, and i dont know if the previous owns did it or not. Would that make a big difference and how difficult is it to do it???

I keep up on the oil changes doing them myself to make sure it gets done right. Once i change the pcv valve i will let you know any improvements or not. But any kind of help would be great!

 

CHANGE the plugs (there are 16 if you have not noticed yet). If no one has done it you are way past due. Every 30K.They are not easy, but not impossible. I was looking at mine over the weekend. Looks like the airbox should come out, and the 3-4 plugs back by the brake booster will take some time.

 

Well I have small handsso gettinginto smallplaces shouldnt be an issue.but I get mixed opinons on them, some say dont worry about it, others say way past due.

love the viper!

 

A dirty TB, faulty PCV and EGR valves are usually the other culprits that result in losses of MPG's from the norm, aside from the obvious need for a tune-up.
I'd do the plugs especially if you do not know when they were last done. Also a switch from conventional lubes to synthetic not only in the crankcase, but the diff(s) as well will usually squeeze you another mpg or two...

 

I have been told that they add ethenol to fuel in the winter and that can cause a few mpg loss. If you live in ethenol country in the midwest, try to stay away from it. MyHemi hates it. I get 13-14 freeway on that ethenol laced crap and 19-20 without it.

 

EGR Valve, can you show me a picture or tell me where it would be??? Something i can clean myself?

Also i noticed driving around yesterday driving i was getting a bit better MPG but them sitting at a drive thru like 2 mins it would drop to 5mpg....is that normal....Ive never noticed that before yesterday. I know it should drop a bit but not from 13-14 to 4-5mpg