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I have strange situation, when I go to put my truck in reverse the RPMs drop and the engine dies. Now this only happens after I the truck is warm and I have been driving it. It does not do this when I get in the truck and put it into reverse first thing only after I have been driving it. It also does not end up stalling if I catch it and get the RPMs back up. Any thoughts on this one?
Just a guess....but sounds like the TC is partially engaging,like I said its a guess.I am sure one of the tranny gurus will be along and more helpful on this one.
It could be the TC locking but you would think it would do it on forward too.... IDK?
My WAG:
It may be the Trans Range Sensor (TRS) on the side of the tranny is out of
adjustment or needs replacement.The TRS has caused all sorts of unusual
engine/trans symptoms.
Yeah several times. A reliable tranny shop is hard to come by around here. I had it rebuilt 3 times within the 1 year warranty period. I would get more input from here though before you rip it out and have it rebuilt. This is just my situation.
It could be the TC locking but you would think it would do it on forward too.... IDK?
It will do it in reverse first. Reverse has a higher line pressure requirement than forward, and if the pump can't maintain pressure the first place you'll see it is at idle speed in reverse. If line pressure drops the torque converter clutch will drift on. If it drifts on enough it will stall the engine.
This can be caused by low trans fluid, a loose internal filter, an internal leak, or a worn pump.
It will do it in reverse first. Reverse has a higher line pressure requirement than forward, and if the pump can't maintain pressure the first place you'll see it is at idle speed in reverse. If line pressure drops the torque converter clutch will drift on. If it drifts on enough it will stall the engine.
Could you explain that a little more?
I thought that the pressure applied to the center of the input shaft locked the torque converter. Line pressure was applied to lock it, and the solenoid released pressure to release the clutch. From what you stated, I must have that wrong.
Is there a hydraulic circuit diagram available for the transmission? There isn't one in the Ford shop manual or an aftermarket E4OD manual I have.
I'm sure there is a hydraulic schematic somewhere, I had one when I was at Ford. I don't have it any longer.
There is converter apply pressure on one side of the torque converter clutch, and converter charge pressure on the other side. Both of these pressures are fed from line pressure, but limited to 120 PSI. When the pump can't keep up with demand it cuts pressure to the torque converter to maintain pressure to the other clutches. The theory is that the torque converter can still operate without a fresh supply of oil for a short time, but clutches can be destroyed in a couple seconds without pressure.
By the way the circuits work converter charge pressure will bleed off faster than converter apply. Now you have apply pressure forcing the clutch on, the clutch applies, and the engine stalls.