This will let all here know that I enjoy this forum and read it several times a week.

I apologize for the long post.

I am experiencing a problem with my current F150 which is used for every day transportation as well as a work vehicle when needed. Up front, I note that I am on the most part very pleased with this vehicle and also, that I when I buy a truck, I plan to use it right down to the ground before trading for another. This means 250000 miles plus.

I have a 2000, F150, 4.6L, 4R70W, 3.55LS, Super Cab XLT with bed liner tool box and headache rack. Normal passenger, tool, and cargo load is about 800 pounds. The truck has 43000 miles on it and runs flawlessly, almost.

My problem occurs while driving highway speeds in OD using Cruise Control in the 65/70 mph range or 1800/1900 rpm.

When an incline is encountered, the computer controlled transmission reacts. First, the torque converter unlocks and rpm increase by about 400. If the incline steepens, the next step is a downshift from OD or 4th to 3rd and the rpm increase another 400. At least, this is how it should work. My truck, sometimes, once the downshift to 3rd is complete will downshift again to 2nd which jumps the rpm by close to another 3000 when driving at 70 mph which amounts to an rpm change from 1900 rpm to about 4600 rpm. Immediately upon completing the shift to second, it returns to 3rd and will then work its way up in the normal way. This procedure is very smooth, very annoying due to the noise created by the increase in rpm, and I cannot imagine that it is good for the transmission.

This does not happen if I am not using cruise control or if I am using cruise control and driving at speeds in excess of 2000 rpm. My conclusion is that the shift points while in cruise control are erratic under 2000 rpm because the computer may have a shift rev limiter that somehow stimulates the downshift to second while in cruise. I believe that driving in access of 2000 rpm probably exceeds the shift rev limiter setting thereby not allowing the to second gear downshift.

If this assumption is true, the solution should be simple. I should either not use cruise at all or drive at a speed that requires 2000 rpm or more. Neither of these is a viable option. Speeds that utilize more that 2000 rpm are simply too fast and I enjoy the convienence of the cruise control.

I am wondering if changing the 3.55s to 4.10s will rectify this situation. It should lower the shifter speed limiter if there is one to under 65. If so, this will help and I believe that the 4.6L would become more drivable as well.

Can anyone here offer an experienced comment on this?

Thank you in advance.



George

 

My 5.4L does this at times too. Normally, I just lock out OD when encountering a hill.

 

This, I've done and it works but it is a complete PITA if one does much traveling in central Texas rolling hill country.

I am seeking a solution for the long run. I am expecting to get 250K to 300K out of either this truck or another. There is no question that I am partial to this truck and my choice is to modify it rather than trade for another. I just don't want to spend the next two to three hundred thousand miles teasing the foot feed or the OD in order to overcome a close to 3000 rpm surge that is not necessary in the first place.

I am hoping to find some one here who has both experienced this same situation and addressed it by dropping the ratio to learn if that is a viable solution. If it is, that is what I will do. If I cannot find a solution, then, it will be back to the drawing board.

BTW, this is posted both here and in the Misc, Transmission, Differential, Transfer Case forum. One may need to be deleted.

Thank you for your response.



George

 

how long do u think that would take and how much money

 

or when u see a hill you could just let off the gas some so it doesn't downshift...

 

I would think that the 4.10's should cure it, at worst, it would unlock the converter but stay in OD.

 

George,

I had almost the same problem with my '98 4.6L. My truck, when climbing a hill with CC on, would not downshift even after losing 10 to 15 miles an hour. Then when I'd give it some gas it would shift from OD to 2nd. I didn't consider the gear change. However I did find a solution! I bought a Superchips 1715. It gave me the 10% more HP they promised. And improved the tranny shift charicteristics 1,000%. Cruise Control or not, it shifts up and down the way it should. Now between the increased HP and improved shifts I climb hills with no problem. Even driving the mountains of western NY, which I do once a year, is no longer a problem.

Good Luck,
Bill

 

I was going to mention the possibility of reprogramming the shift points, but it's basically what Bill wrote. I would have figured that by reprogramming the computer or adding a chip the truck would perform better and you could keep the gas mileage that a set of 3.55s provide. 4.10s would drive that mileage down a couple points.

-Kerry

 

Thanks, LxMan1! I am learning now that the 2000, 4.6 V8 synchronizes the speedometer via the on board computer and Ford tells me that they have no program to perform this operation. The gears are availabe both after market and from Ford but buying a tuner in addition to the gears and labor really makes the change cost prohibitive. Now, I'm sorta back to square one.

Obliged for the input



George

 

Bill, this is one idea that I have given some thought. Your blessings on it are encouraging. However, I am shunning a tuner because of the cost and because its program would be lost in the event that the on board computer died for whatever reason. A chip that could be programed to do the same job and utilize 87 octane gasoline would not be lost and could produce the same benefits and at a possible saving to both the investment and the program. So far, I have been unable to find single program chip that will do this.

At this point, I have just about decided to not do anything but drive it as it is and should the transmission fail, have it rebuilt to meet the need that I feel Ford should have done in the first place. This may be sour grapes but as the governor of California might say it looks like I bought a girlie truck.

Thanks for the input.



George

 

Kerry, as mentioned above, I haven't found a single program chip that allows the use of regular gasoline.

Your milage comments are well taken, but are not applicable in my case as function holds priority over economics.

Thank you for your reply.



George

 

George,
You can get a chip with a single custom program from Superchips. They'll program what you want 87,89,91. 93 Octane. And give you the kind of shifts you want.

Bill

 

Well, it looks like I may have missed the forest for the trees. I recently reviewed their products and completely missed the chip to which you refer.
I will revisit their site and try again. Thanks again for your help.



George

 

You have a private message. Check your FTE mail.

Bill

 

George, if you just change the ring and pinion computer re-calibration shouldn't be required.

Fords use a speed sensor on the rear diff that reads the revolutions of the ring gear. So no matter what ring gear you got in there, it just reads the pulses and sends that info to the computer.