I have a 2000 Expedition 5.4 4x4. The transmission bucks under acceleration and light loading. It does this more noticably when pulling a trailer. I had the trans rebuild with a shift kit and dual disk torque converter upgrade. Trans still does this. The drive lines and joints have been checked and OK. Lube changed and friction inhibitor added to the rear. Limited slip checked and OK. Vehicle has 133,000 miles plugs changed at 100,000 miles. Running an Edge set on towing. Programed back to stock vehicle still bucks not quite as bad. No codes are thrown. Any ideas???

 

what kind of plugs and change your coils

 

Probably a low grade misfire - if you didn't use Motorcraft plugs, change them again, and get a new set of coils on Ebay from Global Automotive or Uneek Supply. Look for DG508. A set should be about $80 shipped. Make sure you use dielectric grease in the boots, and torque the plugs to 28 ft/lb dry - NO antiseize.

 

EGR issues can cause this too, but you usually get a CE light with that.

Darrin

 

Thanks for the replies. Since I wrote this I had the vehicle scanned while driving. OF COURCE it did not malfuntion so no codes showed. I am not sure the type of plugs that were used, I will have to find my reciept. Today the mechanic suggusted to change out the coils. How bad of a project is it to change the coils?

 

not trying to make you feel stupid or anything but... does it do this randomly while you drive or only when it shifts. just wanted to make sure, there have been people who freaked out because they put a edge on and now their trans shifts hard.

if it is the coils all you need is new coils, small hands, beer, time, and to be very very flexible. its pretty easy just takes time. i did it in about 2hrs. be careful the rubber boots are a b**** to get off and can break.

 

Thanks for your reply. It is not the shifting as when I had the trans rebuilt I put in a shift kit and a duel disk torque converter so it does shift harder and quicker. It will do it inbetween shifts and when the trans is not shifting. Bought 8 new coils from Global yesterday, if I get brave I will put them in. Mechanic told me the left side is easier so I will do those and if the problem goes away I will have 4 for a rainy day.

 

it's not hard, trust me you just need to be flexible and sit on the front fender with feet on the exhaust manifold and head under the hood, unless your like 8ft tall. also craftsman makes a flexible socket extension, not swivel flexible get one it will make it so much easier.