6.4L Power Stroke Engine and DrivetrainDiscussion of the 6.4L Power Stroke diesel engine and drivetrain in the 2008 Super-Duty trucks. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 6.4L Power Stroke engine.
Automatic transmission shift question while under load.
My transmission seems like it changes weird. When under HEAVY load. When it shifts in the next gear, it will make a shift, like its making a shift into a gear "in between" gears. Then it will finish the shift and go into the gear. So..... there is a hesitation, then a shift into what seems like an in between gear, then another hesitation, then the shift finalizes. Does this happen for you? Just doesnt seem right.
Your help is appreciated.
__________________
2008 F-350 Dually Superduty 6.4, 4.30 rear end, 4x4 King Lariat package and one heck of a truck payment.
Re: Automatic transmission shift question while under load.
Long shot answer--TC lock-up and gear shift to close together?
One of those hesitations may not be a gear shift but your torque convertor locking up. Sometimes its hard to tell which is which. [img]/forums/images/%%GRAEMLIN_URL%%/crazy.gif[/img]
__________________
2001 Ford F-250 PS, CC, 2/w drive short bed, auto(BTS upgrade), Banks Stinger Plus and exhaust brake, TurboSaver, HX,Hutch mod/pooned, K&N FIPK, Mag-Hytec trans and diff pans, Cyclone fan, doodad, Bilstein shocks, Air-lifts front and rear,DI 4-pos chip, Evans/203therm, fuel regulator shim, GOS headlight harness/silverstars, Bob's coolent filter, Rotella Syn w/single by-pass.
Re: Automatic transmission shift question while under load.
<span style="color: blue"> yougotme ,
Between what gears is it "hesitating" at? The transmission is still the 5R110, but I have heard that there are some differences between those behind a 6.4L and a 6.0L. Some one correct me if I'm wrong, but I don't believe that Ford changed the shift strategy, and if they haven't, you could be having the 2-3 shift hesitation. It's not really a hesitation, though, because during this shift, the transmission has to disengage one set of clutches and engage another set (unlike only one change in the other gears), so it takes more time during this gear change than the others.
If you have noticed a change during this shift from what I described to a much longer hesitation, then you could have sticking solenoids. The solenoids control all the shifting done in this transmission with commands given to them by the computer. But one thing to mention is that by controlling the transmission in this way, the computer has really good monitoring capabilities and if something is wrong, it will start falshing the Tow/Haul light on the dash and most likely store a code.
Now, if you're experiencing this at higher road speeds, then HoneyShucks touches on a valid point. When you get in Sixth gear, yes I said Sixth, there is one more action done by the transmission and that is to lock the converter. You will be able to tell it's locked by watching the tachometer. When you count the Fifth shift, watch the tachometer and feather the throttle a little. When you press it down, you will see the RPMs rise a little and when you let off a little, they will drop accordingly. Now, while the converter is still unlocked, hold a steady throttle position and watch the tachometer. If everything is working right, you will see it drop about 200-300 RPMs, at which time you can press the accelerator some (not enough to cause a downshift) and the truck will begin to accelerate but the tachometer will not immediately rise in RPMs at it did with the converter unlocked. It will now act like you are driving a truck with a manual transmission, as the input of the transmission (torque converter) will be solidly coupled to the output of the transmission through the torque converter clutch.
I hope this helps explain things a bit, and please give us some more detailed description as to when this is happening, so that we can try and better troubleshoot the problem, if you are having an actual problem.
Re: Automatic transmission shift question while under load.
Dropped truck off at the shop today. Seems like they are going to tear into the transmission, but thats I all they said.
The tranny was doing this weird shift at highway speeds. I noticed first when pulling up a hill, keeping it at 55, with the 16k 40ft 5th wheel in tow. My truck is rated for 17,700 if I remember correct. Didnt see the reply from you Joey till it was too late to try the 5th-6th deal you were talking about. So I am still at a total loss about this. Guess we will have to wait to see what the dealer say.
Truck was put into service for:
1.new leather seats (seats had these burn looking marks on it from factory, they are replacing all the skins)
2.erratic idle
3.driver door needs adjusting
4.speakers keep cutting in and out.
5.tranny shift problem
6. oil change ( this is my second oil change, first at 3k, and now at 5.3k )
me
__________________
2008 F-350 Dually Superduty 6.4, 4.30 rear end, 4x4 King Lariat package and one heck of a truck payment.
AutoForums.com is the premier network of enthusiast-owned
enthusiast-operated automotive communities.
We operate more than 100 automotive forums where our users consult peers for shopping information and advice, and share
experiences and opinions as a community.
Linear Mode
