I was on a gravel road today and decided to stop and engage 4 wheel drive since I have only done so once before since purchasing the truck. I started by engaging 4 low, no problems engaging. When I started to go it shifted very rough, literally jerking forward. This happened in every gear it shifted as the truck increased speed. It also downshifted very rough when slowing down. I know this can't be normal as my '05 never shifted even remotely like this.

So I decided to try 4 hi. No problems and everything seemed normal as does 2 wheel drive.

Anyone else encounter this in 4 low and any guesses as to what might be wrong?

 

It prob just because your in 4 lo. Feels totally different on mine compared to 4 hi. Think it's just the way the ratios work.

 

Ya... I realize the difference between 4 hi and 4 low, but that very rough jerk forward just doesn't seem right and it shifts in every gear like that as well as downshifting. I realize that tranny is different, but my '05 never even remotely shifted in 4 low like that.

I'm due for an oil change soon so I will inquire about it at the dealer.

Love to hear from anyone else who has noticed this as well.

 

exactly how fast were u going in in 4l?

 

I wasn't really paying too much attention to the speedo, but I would guess I took it up to 15 -20 mph tops or roughly thereabouts. enough for it to shift several times.

As I explained before I realize the extremely low gearing of 4 low and how it supposed to feel, but the very rough shifting just jumped out at me and caught me sort of by surprise. My '05 shifted much smoother. Maybe there is something different about this tranny. I've briefly read some things about this new transmission and how the computer is controlling the shift points as it learns your patterns. But in 2 wheel or 4 hi everything seems ok, it's just 4 low that really makes you jump up and take notice.

 

I've spent a good amount of time in low range without problems.

 

Do you recall how it shifted? Was it rough or very jerky?

 

Make sure that you are at a full stop, trans in neutral, before shifting into Low range....

 

Sounds normal to me, I have only even gotten it to shift to 2nd while in 4low as there is no real need to go faster than that in 4low; any faster, try 4hi.

The manual only mentions not using 4wd above 55mph to switch to 4hi, 4low is going to be considerably slower.

Page 167 of my '04 manual
"Shifting to/from 4L (4WD Low)
1. Bring the vehicle to a complete stop
2. Depress the brake
3. On vehicles equipped with an automatic transmission, place the
transmission in N (Neutral); on vehicles equipped with a manual
transmission, depress the clutch.
4. Move the 4WD control to the desired position.
• If shifting into 4L (4WD Low), wait for the 4X4 LOW light in the
instrument cluster to turn on indicating the shift is complete.
• If shifting out of 4L (4WD Low), wait for the 4X4 LOW light in the
instrument cluster turn turn off indicating the shift is complete.
Note: Some noise may be heard as the system shifts or engages; this is
normal."

 

I'm well aware of the procedure for engaging 4 low. This isn't my first F150.

I had a chance to try it again only this time pay a little more attention to speed and RPM's. Once engaged in 4 low from a dead stop, i give it some gas and the engine will rev till the rpm's reach between 2500 and 3000 before it shifts. It sort of seems like it is slipping before it engages each shift. Hard to put into words, but as the rpm's increase the vehicle's speed doesn't until it shifts. When it does shift it's a very sharp jerk. speeds were from a stop up to 20 mph.

I dunno, if this is normal it sucks big time. I don't see how it could be that much different than my '05 (new transmission or not). I guess I'll just have wait till service can take it for a drive and see what they say.

 

Seemed very smooth to me. The last truck I really wheeled was an 89 f150 stick shift so maybe my perception is different than yours.

 

We'll I brought it in to the dealership this afternoon as I was going to get an oil change and had one of the service guys take it for a drive with me. After driving it he agreed that something is definitely not right. So I set up an appointment to drop the truck off Thursday morning.

I knew that couldn't have been normal. Even when he drove it you could feel and hear the engine revving, but the truck wasn't gaining any speed then a sharp jerk as it shifted and the whole process started over again. it very much felt like a slipping tranny. The only question that I have and one that I don't fully understand (I'm not an auto mechanic) is why is it only isolated to 4 low. Transfer case maybe??

I'll post back when I find out what the problem was, in the meantime I encourage everyone with an '09 to check their 4 low operation if you haven't already.

 

you do realize that 4l isn't meant to be driven on dry hard packed roads. and that you are not meant to go fast in 4l, my guess is there is nothing wrong, and your trans would not slip in just 4l it would slip all the time. and if the trans was slipping it would set codes and turn on a the wrench light, and if there was a problem with the t-case it would set codes and turn on the 4x4 malfunction light.

i really think you are misinterpreting axle whined up and the really low gear ratio on dry roads as a problem. and the tech road testing on dry roads is just wrong as well.

 

Deano, all of MY testing was done on loose gravel. I may indeed be misinterpreting axle wind up as you call it and you may be right about things being normal. But if they are this will be the first of many 4 wheel drive trucks (all fords) that I've owned or leased and NONE have ever shifted this rough or displayed this kind of slipping sensation in 4 low (not even close). My last truck an '05 certainly didn't.

As far as the service person driving it on dry roads. We'll... we didn't have a whole lot of options as the concrete jungle stretched as far as the eye could see. I don't think this gentlemen was a mechanic (not sure what his title was, maybe a service writer) but he seemed fairly confident that something was not right.

Either way we will find out soon enough if something is amiss.

I do appreciate your comments though Deano as well as everyone else. I will report back when I find something out.

 

I also noticed this when i tried out 4lo and would be interested in hearing what you find, definately something is different from my 06 it jerks hard in every gear with only very light throttle. I have the FX4 with 3.73 rear end.