RPM drop
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Joined: Oct 2006
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RPM drop
I have a 2002 F150 XLT Supercab with a 5.4 Tritan engine. Lately when driving at around 55 or 60 mph something strange happens when I let off the gas. My acceleration is fine, but when I take my foot off the pedal it automatically drops 200 rpm, almost feels like it is downshifting, but it didn't. It only occurs at around 55 or above. I can mash the gas again and acceleration is fine. Also it doesn't matter whether overdrive is in or not. Is this something I should be concerned about?
Lead Driver
Joined: Sep 2006
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There is a feature you may be noticing.
At these speeds you may be causing the computer to unlock the converter as a response to/for an emergency braking action that is built into the system.
The reason for this it to help reduce stopping distance and brake reaction time so the motor does not keep pushing the vehichle with the lockup on.
When the lockup come off, the transmission is back to the 'soft' fluid slip condition of the way third gear is without lockup.
Normally if this happens then some throttle is applied, the computer locks up the converter again on an internal timing function of a few seconds.
You can test/see this action happening on the Tach.
Don't know if that's what your seeing or some other issue.
Good luck.
At these speeds you may be causing the computer to unlock the converter as a response to/for an emergency braking action that is built into the system.
The reason for this it to help reduce stopping distance and brake reaction time so the motor does not keep pushing the vehichle with the lockup on.
When the lockup come off, the transmission is back to the 'soft' fluid slip condition of the way third gear is without lockup.
Normally if this happens then some throttle is applied, the computer locks up the converter again on an internal timing function of a few seconds.
You can test/see this action happening on the Tach.
Don't know if that's what your seeing or some other issue.
Good luck.
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
This feature along with another issue at the same time could be confusing unless carefully observed.
The feature has been in all electric controlled transmissions since about 1984, even in the Rangers and Bronco II.
Good luck.
The feature has been in all electric controlled transmissions since about 1984, even in the Rangers and Bronco II.
Good luck.
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flixden
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Mar 15, 2012 08:31 AM
