1985 Other Oldsmobile Models lurches when braking at low spe

BS_85_OLDS_DELTA_88_ROYAL

MEMBER
1985 OLDSMOBILE

Engine Performance problem
1985 Other Oldsmobile Models Two Wheel Drive Automatic 38,000 miles

my car has started doing this thing where when I brake, doesnt matter if its hard, soft, or anywhere in between, when the speedometer gets downt to around 5 mph during a brake the engine tryes to die. And it surges so that the whole car lurches, and the check oil dummy light comes on with the pulses. Now if I do a hard brake from 40 mph down to 10 mph it doesnt have a problem, but if im going 6 mph, and apply the brake, as soon as it hits that 5 mph mark it starts acting likt it wants to die. The oil light pulses with the enging when this happens, it doesnt come on and stay on, it doesnt stay on through the entire braking process, only pulses with the engine when braking around 5 mph. I know the fluids are ok, I check them daily. The engine does have a slow oil leak, and the trany has a slow leak from the pan ( I think its the gasket ) but other than that there are no other major problems that I know about. Any one have any ideas of what it might be?

1 Reply

EMHARTAIN

MEMBER
2 POSTS

It sounds like it's a bad throttle position sensor on the transmission downshift cycle. When the car slows to stop under normal braking conditions, the transmission will upshift to first at about 5mph, it sounds like it's not doing it, and the idle goes too low, so the low idle sensor kicks in and revs up the engine to keep it from dying. I'd check the tranny for any upshifting problems and then start checking the throttle position sensor and other sensors that deal with deceleration.