Surging in Manual Gears

[Thor]

When I do a descent on a steep mountain road my 2017 Expedition surges at about a 1 sec rate for most of the descent. This is a run from Alta Ski Resort to the Salt Lake Valley floor. I use third and second gear for most of the 7 mile descent and there is a distinct surging from the engine. I called the dealer about it last year and he said not to worry about it but I would like to know if anyone else experiences this and if it is thought to be a problem. I only have about 11,000 miles on the vehicle and it was doing it since I had less than 3000. It is a little intermittent and seems to be worse at some times than others but it definitely didn't happen with the Suburban I had before buying the Ford.

 

[AllBoostNoEco]

This is the third thread in recent memory on this exact same issue, so in this place that’s fairly frequent. No reports of it causing damage or anything of that sort, so it does seem like something not to fret over.
I have not personally experienced it, as I have never used manual mode in my truck.
Have you tried locking out the upper gears with the +/- on the shifter without shifting into manual mode? And I understand it is steep and possibly snowy up there, but my cruise control is highly aggressive and seems to provide more engine braking than locking out gears does, so might be something else worth trying to avoid the surging.

 

[Muddy Bean]

Can you explain more of what you’re experiencing? If you are in tow/haul mode or have the cruise control activated at the time of descent, your truck will automatically downshift to maintain your cruise control speed or if in tow/haul mode, to perform automatic engine braking. Either of these would make it seem like the engine is surging.


Sent from my iPhone using Tapatalk Pro

 

[NevadaGeo]

I use my Expy off road often and have reported this problem to the dealership. Going downhill, I use the manual mode to lock out upper gears for engine brake. It surges and is a big PITA. Dealership could not duplicate the problem (figures...) but was told it is covered by warranty up to 60,000 miles.

 

[powerboatr]

is it like the tq converter is locking or unlocking? or like a feathering of the throttle? Or lastly is this happening with no feet on any pedal, just letting the vehicle ride the gear?

oh and in 2wd or 4wd or auto 4?

i sometimes use the manual, if we are in stop go traffic and i use gears to reduce speed vice brakes as much

 

[Thor]

This is happening in 2WD and when the trans is in manual mode and I go between 2nd and 3rd gears, depending on how steep the descent is. No feet on the pedals other than occasional mild braking when speed goes above what I want. Wouldn't know what locking or unlocking of the torque converter would feel like. Have not tried it in cruise control mode and I am not in tow/haul mode. That would be interesting to try. I do this to provide more control and to minimize brake wear. It is not something subtle, it really surges and it is interesting how it is so repetitive and at very close to a 1 sec rate.

 

[Thor]

Just read my reply and I should make it clear that it is not happening in the transition between 2nd and 3rd. It happens continually when I am in either of those gears. Not noticeable in 4th or above but in those gears I wouldn't be getting any engine braking under these conditions.

 

[NevadaGeo]

The lurching occurs in all gears regardless, no throttle but some braking. It could be the torque converter. It seems to grab and let go like the torque converter is locking and unlocking. Never happened in my old 2012 F150 with the 5.0 V8 under similar conditions.

 

[bobmbx]

By "surge", do you mean more power is being applied (engine changing state)...or is it more like a brake released and the truck starts to accelerate from gravity (transmission changing state)?

 

[Thor]

It is more like a brake being applied and released. It is like the compression braking is being applied and released. It is a constant 1 second pulse rate