Hi there. I have a 99 F-150 4x4 shortbox with the 4.6. I have an air intake system and dual flowmaster exhaust. I only use this truck for towing my 2500lbs boat. i also recently rebuilt the tranny. During my last two trips out with the boat i could not keep it at 100km/h on the freeway without it kicking in and out of overdrive even while on flat stretches. Do i have any options? Computer chip? Luv the truck but maybe the engine is just not big enough?

Thanks for any advice.

 

i heard your not suposed to tow with overdrive on, i never do and my truck tows my boat(about the same wieght) fine but i also have the 5.4

 

Re-gear it

 

Read your manual,it should say do not tow with OD on, thats probably what wrecked your tranny in the frst place. Also how did it tow before the tranny was rebuilt,maybe there is a problem with the rebuild!

 

ya regear! but you can change your shift points w/ a programmer if you want to save your money for the time being. i havent regeared but i did have constant shifting in and out before my programmer. its basically completely fixed now. if your wondering i have a sct xcalII tuned by vmp. definently recomend them. its about $410 shipped.

 

As long as the trans can stay in Od with the converter locked it is fine

 

i towed/hauled about 3800lbs with my 97 5.4 for over 1200 miles and i towed with overdrive on. and i didnt have one bit of problem. if im not mistaken you will be fine as long as u dont keep shifting in and out of gear which could also be the torque converter is locking and unlocking. but yes a programmer would help you out alot beening that you do have 4.6. im currently waiting custom tunes from Bill at Power Hungry Performance. go look around at the 3 main tuners,talked to them and see which one u like best.

 

Get you a tuner that will help you out, and take that slowmaster off, that pos robs you in the low end tq department.

 

My old 97 4.6 would lock and unlock the converter while towing on the highway. I can program the converter to stay locked to MPG is improved and heat is drastically reduced. Towing in OD is fine, as long as it is not switching in and out of gear constantly.

 

Id get it tuned by Justin....