muzzman1

I was under the impression our (automatic) Is's have a rollback prevention system....the car does indeed "slow" the roll back on a hill, but tonight (for fun) I tried it on my street which is a 13% grade.....the car did slow its roll, then surged slightly, then started rolling back (after the trac light came on) then proceeded to STALL!
Does anyone know the details about this feature? I looked for it on the lexus website, but found nothing....

rominl

iTrader: (4)

well, i guess it can only hold till a limit. 13% that's really steep. maybe it will try to prevent roll back but doesn't mean you let go of brakes and no gas and it will continue to hold there?

flipside909

The New IS has something similar if not..HAC (Hill-start Assist Control). It's not designed to keep the car from rolling back at a 13% grade. It's designed so when you release your foot off the gas pedal, the car doesnt jerk back or roll back out of control.

muzzman1

That is what I was looking for!! "HAC" I realize that 13% is steep...point was is that the car stalled! I noticed on less steep hills it does in fact "stop" the roll back....after about 1 foot or so...

mcfly

It does have rollback prevention... it's called the brake pedal. You'll also notice, oddly enough, that you have two feet. Using one on the accelerator and one on the brake ... I know, I know, this sounds horribly complicated, but bear with me... it's quite possible to prevent rollback in any situation

Bichon

No, our creator provided us with a left foot to operate the clutch pedal.

The brake, even on a car with an automatic transmission, is properly operated with the right foot. If you can't get your foot from the brake to the accelerator fast enough to prevent the car from "jerking or rolling back out of control", it's probably time to see your doctor.

muzzman1

Ha Ha....funny guy....the point of the thread was to see if anyone could elaborate on this feature...trust me Ive been driving for 20yrs, I built and race a 9 second car...i know all about driving....thanks for the reminder about my left foot!

rominl

iTrader: (4)

the point is the system will give some power to prevent rollback, so that you can let go of brakes and go to gas and go. it's not going to sense the super steep road and that the driver keeps on forgetting to put on gas and start reving your engine to 3000 rpm to keep it steady.... you tested the sytem past its limit..