A couple of questions (boosting/idling)

[longman h]

Evening fellow RS family members, I'm after some info please.

So when I'm accelerating pretty hard and take my foot off the pedal, there's a sensation like the car's applied the brakes quite hard/sudden jerk and I was wondering if this was normal? I can only assume it's because I'm cutting the boost to the turbos.

Another thing I've noticed is that once the car's warmed up and you're in D, when I come to a standstill with my foot on the brake and the car's just idling, it seems to vibrate a little more as if it's become more eager to move forward again. Is this normal?

I've tried searching but it hasn't revealed anything so hopefully you guys can help.

Thanks, H.

[skirs6]

I will try to answer your questions in the morning going to work

[longman h]

I will try to answer your questions in the morning going to work

Not driving I hope!!
Thanks mate.

[Ungjaevel]

Boost: I'd say that sounds quite normal. (Sudden jerk part, not applied brakes hard part). It's not because you go off throttle, has nothing to do with boost, but kinetic energy. At least that's my take on it.

Idle: When in "D" the only thing stopping the car going forward is the brakes. So yes, it's supposed to want to move forward. (Imagine being parked in an uphill position, going from parked to drive. If not wanting to forward your car would be going backward... not good.

[IanH755]

If you want a 2nd opinion I can pop around (you're not far from me) and you can take me for a spin and I'll compare it to mine?

[longman h]

Thanks chaps and Ian, I may just take you up on that offer. Where abouts are you based?

[IanH755]

PM Sent!

[TomRS]

Sounds fairly normal bud! Ian's a top fellow and will have a good look for you.

But the off boost thing is because the power delivery is so linear you dont feel the power until you let off the throttle then it throws you back forward normally.
I'd not be concerned with that at all! unless your brake lights are coming on haha!


As for the idling thing, yes thats also quite normal as the car is using some of its engine power to try and move itself forward, think of it as a water pump on a petrol powered jetwash.
You engage the pump and the revs drop it vibrates more as its under load you let off the revs increase as you've removed the load, thats exactly the same as the Automatic box, in gear its under load in P/N its not under any load so the revs are higher.