Something weird is happening on my 09 MCSa, and I was wondering if anyone else has experienced it...

If I am parked facing down a hill and I put the car in reverse and step on the gas, it hesitates for a little over a second and then "knocks" into motion. It also gives a bucking sensation through the pedal. If the car is parked on a level surface, or uphill, everything is fine.

Is this "normal", or should I take it is to have it checked out.

 

Does not sound normal to me. And I have not experienced this in my 08 Auto.

 

Does it happen both when cold and hot? Are you allowing it a second to shift into reverse before accelerating?

 

This sort of sounds like the hill assist kicking in (car automatically applies the breaks for you until it senses the engine can take over and not let the car roll down the incline). But if it is only doing it in one direction there may be a problem with the car.
Does it do this when facing uphill and putting the car in "Drive"?

 

It does it when the car is hot. Haven't had a chance to test it cold...I only park it on a level surface at work and home.

I can shift into reverse, wait with my foot on the break pedal, then when I apply the gas it will rev for a second or so, then bang into motion. I haven't tried revving the engine higher than normal because I am afraid it will bang in really hard and really mess up the transmission.

The car works fine in drive. I have not noticed the problem under any other conditions.

 

I've just assumed it was the hill assist and enjoyed not rolling forward (or backward, depending on the hill). But then again, I've never experienced it as a knock or a bang, just the transmission taking hold.

 

i'm guessing it's just hill assist as well. kind of annoying when parallel parking. i just shift to reverse and wait a second for the car to "unassist" itself before touching the accelerator. otherwise it'll jerk back as you described.

 

Without actually seeing it, I can't be sure, but it sounds like hill assist as others have said.

 

ok, thanks. that is a relief.

 

Hill assist can be kind of unnerving if y're not used to it. my 09 MCSa does the same thing. I beleive all's well here.

 

I had a loaner 09 MC that did that. Would not go in reverse and when you added gas would take off like a rocket. But it would also roll back on a hill. I would have the dealer check the car just in case.

 

My driveways in a bit of slope, and yes it does that if I go forward or back it up. just go of the brake and slightly push the gas not enough to rev the engine up, i'd feel hill assist goes off and than I will start pushing the gas pedal.