Took my 17 XLT ecoboost up into the mountains for some tubing today. On the way down the mountain I locked out 4-6 so I could engine break down most of the windy twisty road in 3rd gear with little break input. I began to notice the truck was surging or bucking as it rolled down the hill, with no throttle applied. I shifted into 4th, same feeling but at a higher rolling speed. Same thing in 2nd but at slower speed.
Applying throttle made it go away. No corresponding rpm change while it was surging or bucking though. It almost felt like the converter was locking and then immediately unlocking, or driveline slack? I put truck in 4x4 though, no difference. Only way I got it to stop was giving it gas, not a good idea on this narrow windy steep downhill road covered in snow and ice.
Anyone else noticed this? Truck has 43k miles, spark plugs were changed at 35k. No check engine lights, although it did feel like it was lugging very badly at all times and not wanting to downshift without liberal pedal pressure during the normal part of the drive. I'm running a 5 star performance tow tune and it feels like I'm not building boost any longer either (like it's lost that woosh feeling when you gas it, just loud motor). Gonna return to stock tomorrow for grins and see if things change. I would imagine if I were having a turbo problem or would throw a code for underboost ?
Applying throttle made it go away. No corresponding rpm change while it was surging or bucking though. It almost felt like the converter was locking and then immediately unlocking, or driveline slack? I put truck in 4x4 though, no difference. Only way I got it to stop was giving it gas, not a good idea on this narrow windy steep downhill road covered in snow and ice.
Anyone else noticed this? Truck has 43k miles, spark plugs were changed at 35k. No check engine lights, although it did feel like it was lugging very badly at all times and not wanting to downshift without liberal pedal pressure during the normal part of the drive. I'm running a 5 star performance tow tune and it feels like I'm not building boost any longer either (like it's lost that woosh feeling when you gas it, just loud motor). Gonna return to stock tomorrow for grins and see if things change. I would imagine if I were having a turbo problem or would throw a code for underboost ?