I had 4 almost bald tires (265/75r16), wobbly ball joints, my front alignment was out almost 4 degrees. I had to change everything so I could get a passing inspection sticker. So about 2 weeks ago I put on 4 brand new Goodyear SilentArmor tires (265/75r16), changed out the original ball joints (98,500 on them) and had an alignment done. Now I'm getting maybe 12 mpg, where I was getting about 16 mpg before in city driving. I am going to try changing the spark plugs, air filter, fuel filter, and trans service in the next couple of weeks to see if that helps. I am thinking about installing Autolite Platinum plugs, and a K&N air filter. What could be the cause of this? I was considering putting a performance chip in also. What are some recommended chips or are they not even worth the money? This is kind of a pile of now!! Thanks for any ideas on this problem.

 

check your brakes make sure they arent dragging, and make sure nothing up front is rubbing, i hope that these are hand calc'd numbers you are giving us and NOT the overhead readings bc the overhead is always wrong (99% at least). also make sure your gas cap is tight and you have no evap leaks (yes there are some that wont trip the light idk why but there are)

 

What tires were you running before? We sell a lot of Goodyear tires here at my shop, and the Silent Armor's are a premium A/T tire with excellent grip. The downside to that is that grippy tires tend to lower fuel economy, though usually not 25%.

But do watch your tire wear closely. It's possible that either a problem with the machine or the alignment tech has your front tires looking at each other a lot more than they should be. Excessive toe equals high rolling resistance. You'll also burn through a set of very expensive tires in no time.

FWIW, 12-14 MPG in town is pretty normal with a 360. The 318 & 360, along with the 4.0L Jeep engine, got replaced because they were not efficient enough. The EPA is the only reason these great powerplants went the way of the Do-Do.

 

I would not use platinum plugs. Just use the champions that are recommended for your eng. I don't like K&N filters you may get a little more HP but not better MPG. How are you checking the MPG (don't rely on the over head computer). Don't know anything about chips. First do a good tune up plugs, wires ect.

 

his sig references the 4.7 so i assume thats what he has, that said, i agree platinum plugs are bad in these engines, and the fact that more aggressive tires will give you a gas mileage hit, but what you got was a bit excessive.

 

Maybe something came loose and is causing resistance, I would ask them to double check the alignment with those findings! Last thing you want to do is waste $900 dollar tires. Just explain the situation to them.

 

shrp, I also just put all new ceramic pads fr and rear. I don't have the overhead comp.

sixtysix, I had a used set of Nokian Vativas that I got from my cousin. I will have the shop recheck the alignment just to be sure it's all good.I do have the 4.7 eng.

Thanks for the ideas guys. I will look into these things tomorrow after work.

 

Oops. Missed that. Assumed 360 in a premium model.

Being that we're now aware it's a 4.7, I'm pretty sure those actually call for NGK 6987's (V-power copper). I'll double check tomorrow, since I can't log into alldata here with all our stations assigned.

 

my underhood label with a 4.7 calls for champions

 

OEM is Champion Copper.