Shifting oddly

Tiny
JADEN MCFADDEN
  • MEMBER
  • 1998 FORD F-150
  • 4.6L
  • V8
  • RWD
  • AUTOMATIC
  • 156,000 MILES
Originally I thought the transmission was slipping but have added a re-conditioner to my fluid and it certainly is not slipping, Peels rubber and never misses a beat. I am unsure if the torque converter is bad or if it could be a modulator valve. When the transmission fluid is cold it does not like to shift out of first gear, I can manually shift it out and it will cycle through all the other gears just fine. Kind of sounds low when in fifth but it is okay. If I take off fast without giving the transmission time to "think" something squeals/ screeches behind the dash, or at least it sounds like it is behind the dash. All in all it seems like it just shifts high coming out of first gear. Oh and sometimes the transmission shudders which I have heard is the torque converter. Any expert advice?
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Wednesday, November 30th, 2016 AT 5:38 PM

4 Replies

Tiny
CARADIODOC
  • EXPERT
A shuddering torque converter is usually caused by using the wrong transmission fluid that does not have enough of a specific additive. To verify that, first be aware the shudder usually only occurs during initial lockup, although my daily driver does it continually, once warmed up, at around 35 mph. You will not feel the shudder below about 30 mph, not unless the transmission is in the highest gears, and not until the engine is warmed up. You should also not feel it at speeds higher than about 50 mph.

When you feel the shudder, hold the accelerator pedal perfectly steady, then lightly tap the brake pedal with your left foot. Doing that initiates an unlock and the shudder will stop for two or three seconds.

A failing torque converter can cause the same symptom, but it is very much less common than using the wrong fluid. A failing torque converter will typically cause shuddering at higher speeds too.
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Wednesday, November 30th, 2016 AT 6:07 PM
Tiny
JADEN MCFADDEN
  • MEMBER
As for the rest of the symptoms?
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Friday, December 2nd, 2016 AT 7:43 AM
Tiny
JADEN MCFADDEN
  • MEMBER
It shudders whenever there is a load. Like going up hills and such, sometimes while going through the gears.
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Friday, December 2nd, 2016 AT 7:44 AM
Tiny
CARADIODOC
  • EXPERT
I have never heard of the wrong fluid type causing the shift timing problem, or failure to shift. Your transmission doesn't use a modulator valve. It is computer-controlled. There is really very little you can do unless you have access to a scanner. The place to start is by reading and recording any diagnostic fault codes. If you find any that are related to the range sensor, (formerly the neutral safety switch), those must be addressed first. Incorrect readings from that sensor will cause the computer to be confused and will likely prevent proper operation. Once the range sensor is verified to be working properly, if the shifting problem is still there, you need the scanner to perform tests on the shift solenoids. That can tell you right away if there is an electrical problem, as in a cut wire or corroded connector terminal. That will also tell you during a test drive if there is a mechanical problem associated with one of the solenoids. That would be seen by the a change in which solenoids are being commanded on but no gear change occurs.

Given the intermittent nature of the problem, you might want to inspect the connector terminals for the range switch first. It is located by the shift lever on the side of the transmission.
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Friday, December 2nd, 2016 AT 5:21 PM

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