I own a 97 f150 extened cab long bed 4x2 with a 4.6 V8.it has around 86,000 miles on it. i took it to my local ford dealership and they cleaned the mass air flow sensor and reprogramed the computer. that was $100.00. i ran a couple of tanks of gas through and still only got 11 mpg. i went back to the dealership and they said i need all new tires and they reprogramed the computer again. that was $550.00. i ran a few more tanks of gas and now i was getting 9 mpg. i took it back to the dealership today and they told me that the spark plugs were gapped too much and that causes more fuel to be burned. for all new spark plugs and installtion was around $270.00. is this going to fix the problem? i drive mostly city miles and do not red line it.i am getting tired of it.

 

[updated:LAST EDITED ON 27-Dec-02 AT 05:41 PM (EST)]I'd say your dealer is fishing and doesn't know what the problem is. That, and you are giving up a lot of your hard earned cash very easily.

It didn't hurt to change your plugs but I think you could've done it yourself a whole lot cheaper. I will be surprised if that solves your problem.

 

Replace your air filter.

 

1) What has been the best MPG that you have ever gotten from this truck?

2) Is the drop in MPG why you took it to the dealer in the first place?

3) Are there any codes?

 

 

City driving? That's probably your biggest gas mileage problem. Especially the stop and go where you lay the hammer down at every green light. Just kidding... I'm not saying you do that, but city driving does contribute to poor mileage.

Example: driving my truck on it's first highway trip of 250 miles or more and I got 16 mpg and I was pleased. Everything external to the engine was changed out except the tires, they (and the truck) had 46K miles on them, so they were well worn originals. The driving was mostly two lane highway, with a lot of hills and slower vehicles that could not be passed unless I floored it. If it were a straight four lane on flatter terrain I could have easily pulled 17mpg, in my estimation, but I would have been doing 70mph vs. 45-55mph. When I drive almost exclusively in the city the mileage dips down to 13mpg. As time in ownership has progressed, my mileage has tailed off even more.

I agree with Skoop: The drop in mileage, I suspect, is due to the air filter getting crudded up more than anything, that's why I change mine out about once every 5-10k miles. I can recall changing it out on other vehicles and seeing instant gains in mileage and performance. I'm not saying that will fix everything, but it was a cheaper fix than the tires, sparkplugs, and MAS cleaning. I agree with Dan's comment, I think the dealer is fishing. As spark plugs go, the gap widens as you use the truck. This causes the fuel in the cylinder to burn less efficiently (aka poor mileage), but with the newer platinum plugs and the 100k mile recommended tune up interval on these engines it's a toss up over whether you really needed that at this time. The computer reprogram may have changed base timing or there may have been a technical bulletin that was never applied to the truck to fix something else. In my eyes it was a quick fix just to say they did something. If the mass air sensor was cleaned, that would be a sign of the conditions you are driving under, dirt has gotten past the filter or the smaller particulate has collected at the sensor boss. I would think that an air flow sensor that is not getting enough air would lead to a check engine light. Tires are only changed if they wear down to within the 3/32" wear mark. People change them for other reasons and it makes them feel secure, but the mileage shouldn't change as long as you keep them inflated to the specs required. You would know if that wasn't the case as the tire would wear funny or you'd experience a blow out. IMO this dealer sounds shady and just wants to nickle and dime you.

To sum it all up your problems could be a combination of several factors. When you rule your driving habits/terrain and all the parts that are normally associated with bad gas mileage, then you have a real problem (something dragging in the drivetrain). I think if you get your truck out on a highway at 60mph for 300 miles with a new air filter on it, you'll be pleasantly surprised at how great the mileage is. If the drive doesn't help the mileage, then you have other issues to discuss with the forum here.

-Kerry

 

I drive the exact same truck with about 85k on it. I did not see if
you said if this was a new problem or an old, but if this has always
been a problem my thought is this: If my research is correct unless you ordered it differently, this model came with a 3.08 rear-end. It is my theory that this high rear-end makes the truck work extra hard. I drive both highway and city. The best milage I have ever gotten was 17mpg on all highway. I usually average about 14mpg in mixed driving. I am considering changing my ring and pinion to a 3:55 ratio and hopeing that will get me a little better mileage. Thats my two cents.