Transmission trouble

[Blvdst]

My 05 4.0L XLT with 118500 miles started having problems between 40 and 50 mph, it is most noticable when going uphill. It appears that it not downshifting. When more rpms are added it downshifts and the shudder disappears. I've been watching the RPMs and it remains near 2000. Last night I drove a bit with the overdrive off and it seems to have helped. Advise and suggestions will be greatly appreciated.

 

[imp]

My 05 4.0L XLT with 118500 miles started having problems between 40 and 50 mph, it is most noticable when going uphill. It appears that it not downshifting. When more rpms are added it downshifts and the shudder disappears. I've been watching the RPMs and it remains near 2000. Last night I drove a bit with the overdrive off and it seems to have helped. Advise and suggestions will be greatly appreciated.

Need a more detailed description. At 50 mph at cruise, encountering a hill requiring a "downshift" will invariably not downshift at all, but rather Torque Converter Clutch unlocks. If more oomph is needed, then a downshift out of 5th. to 4th. At 50-55, those two conditions occurring will result in eng. speed over 3000, perhaps 3500, depending on the mood of the torque converter.

First thing to do would be to check for trouble codes. imp

 

[Blvdst]

Need a more detailed description. At 50 mph at cruise, encountering a hill requiring a "downshift" will invariably not downshift at all, but rather Torque Converter Clutch unlocks. If more oomph is needed, then a downshift out of 5th. to 4th. At 50-55, those two conditions occurring will result in eng. speed over 3000, perhaps 3500, depending on the mood of the torque converter.

First thing to do would be to check for trouble codes. imp

 

[Blvdst]

I will try to describe what is happeing. With the gear selector positioned in the OD mode and driving between 40 and 50 mph the transmission jerks or shudders when going uphill. Stepping a bit harder on the gas pedal will increase the rpms and make the jerk or shudder stop. I believe the transmission is dropping down a gear when I do.this. There are no lights displayed on the dash

When I drove it yesterday and knew I was approaching a hill at those speeds I would turn off the overdrive. There was no jerk or shudder when going up a hill between 40 and 50 mph.

It seems to me there is something electronic wrong, but this DIYer is no transmission expert.

 

[imp]

I will try to describe what is happeing. With the gear selector positioned in the OD mode and driving between 40 and 50 mph the transmission jerks or shudders when going uphill. Stepping a bit harder on the gas pedal will increase the rpms and make the jerk or shudder stop. I believe the transmission is dropping down a gear when I do.this. There are no lights displayed on the dash

When I drove it yesterday and knew I was approaching a hill at those speeds I would turn off the overdrive. There was no jerk or shudder when going up a hill between 40 and 50 mph.

It seems to me there is something electronic wrong, but this DIYer is no transmission expert.

@Blvdst
If the transmission feels normal when driving with the OD OFF, 5th. gear is likely beginning to slip. A trouble code may be present even without the "Check Engine" light on. Most Auto Parts stores will check for codes free. Be aware that some will give vague answers regarding codes, if it appears certain there will be no sale of parts, as in transmissions. See if they will show you the actual code(s) displayed. Write them down. imp

 

[lincolnshibuya]

torque converter clutch might be slipping if it's only happening at that speed and load (uphill) and when you press on the gas it goes away.. either a new fluid will fix or try some lubeguard..

 

[imp]

torque converter clutch might be slipping if it's only happening at that speed and load (uphill) and when you press on the gas it goes away.. either a new fluid will fix or try some lubeguard..

@lincolnshibuya
True enough, but TCC slippage is quickly detected by the PCM, which throws codes related to that fact, as it detects a difference in speed between the engine and transmission input shaft, when they should be equal- (clutch engaged). imp