Hello all, I have a 2000 F150 4x4, with a 6 in lift and 35 in. tires, the problem is, when I am driving and the transmission shifts into OD, around 50 - 60 mph the truck starts shaking and riding really rough. When I turn OD off and the RPM's go up, the truck starts to ride good... I have 170,000 miles on the truck, I have kept up with regular tranny services. I checked the oil in the tranny and it looks brand new and I dont see any metal flakes in it... Could this be the spark plugs? I dont know if they have ever been changed. Thanks in advance.

Brock

 

You may potentially be feeling what is called a "low grade" misfire. If you opt to change the plugs, best bet is Motorcraft, then NGK / Denso. There is more complaints with bosch and champion with continuing to have this low grade misfire issue. also remember to use dielectic compound on the boots too, just for the better.

 

tranny has been shifting at the factory shift points, but the computer is thrown off with the 35's. if damage hasnt been done by all the shifting in the incorrect points, then i would highly suggest programming to return to the factory shift points that are accounting for the 35s. 60mph indicated with 35s isnt actually 60 mph anymore. thats probably beating the **** out of your tranny.

 

yea it sounds like you need a plug change. put some MotorCrafts in and your good to go

 

... if your gonna jump all over the 35's why dont you at least mention gears too?

 

Thanks everybody for the help!! as always this site is the best!

 

My vote for the winning diagnosis.

Darrin

 

and the problem was?

 

Thanks everybody for all the help. sorry for such a long delay before a update, everything has been crazy with the holidays! but I had the plugs changed went with motorcrafts and the coil was bad on cylinder #7, replaced that and she is good as new! Thanks again for everybodys help and advise!

 

Funny I run 44's with 5:13's and My tranny shifts fine .. can even light em when I try real hard....

 

nice! glad i was wrong!