Need help with Auto Stop Start

[Rand]

There should be zero forward momentum with a Start-Stop system. Definitely an issue that should be fixed under warranty.

so the car shouldnt move forward when restarting with your foot off the brake?

Can you explain why it definitely wouldnt move forward while the engine is restarting in Drive?

 

[PimTac]

so the car shouldnt move forward when restarting with your foot off the brake?

Can you explain why it definitely wouldnt move forward while the engine is restarting in Drive?

I believe the problem is the jerking he is experiencing. It should move forward but not jerk or lurch forward.

 

[RamFan]

so the car shouldnt move forward when restarting with your foot off the brake?

Can you explain why it definitely wouldnt move forward while the engine is restarting in Drive?

As @PimTac stated, it’s the jerk that’s an issue.

The engine restarts before the brake is fully released. It should restart and remain stationary until the brake is fully released.

 

[atikovi]

The cynic in me says that as time goes by, we are going to see problems occurring that are caused by the start/stop systems that will be expensive to fix.

But the fact that a 4 cylinder turbo engine is supposed to haul around 15,000 pounds wouldn't have something more significant to do with that?

 

[atikovi]

As @PimTac stated, it’s the jerk that’s an issue.

The engine restarts before the brake is fully released. It should restart and remain stationary until the brake is fully released.

IF the engine management system senses a low battery charge it will start the engine to recharge the battery.

 

[meep]

My Ford has the same transmission. There is an electric pump which pre-builds pressure for instant engagement in the restart. Sounds to me that there is a timing issue in software or in an adaptive on the restart sequence.

congrats on the truck. I enjoyed your description of its driving characteristics. Im a fan of the high torque, low rpm characteristics of the eco boost equivalent. Keep us posted on your experience with it!

 

[Cujet]

Truck is impressive. Pulls like a diesel and keeps rpms below 2000 rpm almost always. When I get the thump or lurch it’s only at approximately 500 rpm idle at startup. Transmission is extremely tight and smooth.

I've been involved in what is now "old school" OEM turbocharged engine development. Mostly stuff from the 1970's and early '80's. It was always clear that a small engine could make incredible power. Even back then we had 1.7L race engines making over 600HP and 2 valve 2.3L street engines making 300HP with full emission controls. Today, with variable valve timing, and variable valve lift, direct injection and turbocharging, the result is fantastic!

 

[robd]

Update, per dealer service department, the problem lies with a motor driven fluid pump inside transmission. This dc pump runs when the engine is off when in drive to keep line pressure up inside the transmission with engine shut down with auto start activated. With this pump not pumping properly, line pressure drops and transmission lurches ahead when restarting when mechanical driven pump spins up on engine restart and vehicle is in drive. A good reason to always keep auto stop start off.