Notice that both Jim veatch and 99F-150Triton5.4 have the same tranny?

Here is my understanding of torque converters. Nomo is correct with his post. The torque converter locks up in third and fourth (OD) gears at speeds that allow for a 1:1 ratio with the engine crankshaft and the tranny input shaft, usually 45mph and above. It is a viscious clutch that absorbs energy for the engine so it does not bog down as it would if the ratio was 1:1 all of the time. It is normal for it to lock and unlock for a number of reasons: hills, loads, even wind resistance on windy days. These reasons may or may not be dependent on each other. It is basically a virtual gear if none of us had it we would get easily below 10 mpg. I have a 98 Explorer with a 5spd. automatic, after the five gears and the torque converter lockup it sounds like a six speed.

I think that 99...5.4's problem is related to the locking /unlocking of the TC since it is nearly undetectable (usually only with the tach). Jim's problem sounds like maybe it was caused by an electronic problem or low fluid. Correct me if I am wrong but isn't the E4OD the same one used for years in Ford trucks? If so it may be one of those things when they put electronic stuff on an old design that may have some more bugs to work out.

My 99 4.6 and my old 98 4.6 both have/had flawless trannies.

Good luck to the both of you and post updates, this has me curious.

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'99 XLT S/C 4.6 Auto 3.55 LS Oxford White,Orlando appearance package, trailer tow package, keyless entry, A.R.E. Hard tonneau, ventvisors and bug guard all painted to match, limo tint, 5 spoke aluminum wheels, Kenwood 6 Disc, black Back Country nerfs, Buccaneers front license plate! I Luv it!

 

well it's been a while since the orginal post but here goes, The dealer duplicated the problem of the torque converter unlocking and said it needs a new converter, it took them a week to order but, while it was on order my T/C unlocked completely and would not lock up at all in OD, so I brought it in last wednesday to get the new converter put in (along with a shaking driver mirror) well he called me today and said the new converter is in but since I was waiting for the converter to come in that I blew the tranny(overdrive), so now I have to wait for the tranny to come in. I hope around this time next week I can have my truck back with a new tranny and converter. Unfortunetely the extended service plan only covers the rental for 5 days so oh wella. I will post when I get it back and see if it runs ok.

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99 F-150 sc, 4x4,5.4,wedgewood blue,mods are on the way