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2004 Ford F-150 rear bumps or bucks on acceleration from sto

Tiny
BALDUR213
  • MEMBER
  • 2004 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 87,000 MILES
My truck is experiencing an interesting issue. When the vehicle warms up and I come to a stop upon take off slow or fast the truck jerks 3 or 4 times.
I can start in 1st or 2nd and shift up to drive with no problems on acceleration. In drive, during acceleration or deceleration, the truck feels like it doesn’t know when to shift. (Taking over drive off made no difference).
I have checked the u joints thinking that might have been the problem but there is no slip on the drive shaft. I think it might be a module or sensor that tells the truck when to shift but I’m just hoping the transmission isn’t ruined.
I have verified the fluid is full and is cherry colored and does not smell burnt. Hopefully it’s something external that I can replace and be done with.

Thanks for any help

Pete Pascale
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Wednesday, April 8th, 2009 AT 5:13 PM

6 Replies

Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
Pete, the pressure regulator and shift pattern are all controlled by pressure switches. The switches are controlled by the computer and the vehicle speed sensor. Are you having any problems with the speedometer?
If you can plug it into a mobile eec scanner, you can visually see what the shifting pattern is doing.
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Wednesday, April 8th, 2009 AT 5:55 PM
Tiny
BALDUR213
  • MEMBER
  • 3 POSTS
I did not notice any trouble with the speedometer. I have and odbii (think thats correct) scanner but it does not give me any codes for the transmission. Its as if the computer is ok with the transmissions shifting. Thats what made me believe this was some sort of electrical module. I have an appointment to bring it to the dealer in the morning. Hopefully I can get to the bottom of it without a huge dent in the checking account
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Wednesday, April 8th, 2009 AT 8:04 PM
Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
I'd appreciate it if you'd let know what they find. I will use it for future reference for others.
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Wednesday, April 8th, 2009 AT 9:27 PM
Tiny
BALDUR213
  • MEMBER
  • 3 POSTS
So I got the truck back from the dealer. Needless to say they didnt fix anything. They replaced a coil which was going bad and the plugs. Did a transmission oil change but still having the same problem.

It looks like the transmission works fine when the truck is cold. Once the truck warms up to operating tempature at normal speeds the rpm's drop then raise like a dowshift or like its falling out of gear. The MPH gauge is fine dosent show any problems at all. It sounds like more and more that the transmission is toast.

Its funny how there are no problems warm or cold in 1st gear and second gear. Only in drive does it give me a problem. It seems like when the trans gets warm either it slips out of gear or something like that. I still pray its a sensor of some sort but sometimes the writings on the wall. Any ideas?
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Saturday, April 11th, 2009 AT 10:33 AM
Tiny
BOWHUNTTCH
  • MEMBER
  • 3 POSTS
I know several people who have the same truck and they all do same thing so dont waist your money mine does it to ford could not repair in two weeks of it being the shop at red lights or intersections just get back on the gas easily until transmission computer decides what gear it is in for the most part in these trucks it is normal.
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Saturday, April 11th, 2009 AT 2:19 PM
Tiny
JAMES W.
  • MECHANIC
  • 2,394 POSTS
It still sounds like you may a control pressure problem. This won't show up in an EEC scan. The only way you can tell for sure is with a fluid pressure test. The working pressure of your trans is controlled by an electronic regulator. If the pressure is low, it will do just as you describe.


https://www.2carpros.com/forum/automotive_pictures/248092_04_Ford_F150_trans_1.jpg

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Saturday, April 11th, 2009 AT 3:38 PM

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