My wife and I bought a new 1999 Exp. with a 5.4L engine, AWD and 3.55 LS axle. I like everything about the truck except the mileage. We are getting 10.2 to 10.4 with a little over 1,000 miles now. This is city and short highway driving. Is anyone else getting this low of numbers? I thought this was the only problem but now I've got my wife and kids sticking their heads out the window every morning. Nothing like a bunch of piston slap victims to make a person paranoid.

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1999 Expedition 5.4L
1996 F-350 4x4 CC PSD

 

Kroy

The Engine is still tight, I'd give it a couple thousand miles before you start getting about 13 city or 15+ highway. I had about 5000 miles before I was getting 13.5 city and 15+ on vacation with the air conditioner on in July. I wouldn't worry about the piston slap. If you get it, you'll know, and a lot of people have done the hard work to make Ford replace the these engines. It's almost old news.

Happy Motoring.


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99 Expedition -XLT-4X4-5.4-17"AT/S- Superchip-Airaid-Polk Speakers-Custom Edlbrock shocks-Rear Swaybar

 

I have a 5.4 99 expy with 9000 miles on it that I cannot get more than 8-10 mpg. I also cannot fill with gas unless I spoon feed it after about 19 gallons. It keeps kicking the pump off. If I stand there and keep trying I can get another 6-8 gallons in. It also takes a really long time to register that it has been filled. My mnfg. date is 6/99. They did replace the mass air flow sensor since when we first got it is was getting on 7 mpg. That helped....a little. if you are having alot of problems (with other parts of the vehicle) please e-mail us jwwatl1@msn.com. We are in the last stages of a repurchase by Ford under the lemon law in our state.