Why does my jeep grand cherokee have an extremely high rpm when I shift it into drive and give it 1/4 throttle

Question

vaccum line busted on the intake manifold. Replaced with slightly larger diameter vaccum hose.Could this be the problem?

Answer 1

possibly

if you're going by what the engine sounds like, instead of by what the tachometer indicates, it could be that you're just hearing the noise from the fan mounted to the front of the engine.

in the early days of automotive competition (when carburetors were used), racers sometimes installed oversized fuel-metering devices in their respective carburetors -- and purposely left vacuum hoses disconnected.

this practice was ultimately outlawed by most (if not all) sanctioning bodies.

racers had theorized that the vacuum leaks allowed more air into the engine (which would ordinarily lean-out the fuel-air mixture, but the racers compensated by making the engine run rich when the leaks were plugged).

in essence, vacuum leaks allowed the engine to act as though it had a larger carburetor.

skipping forward to modern, fuel-injected engines, "EGO" (exhaust gas oxygen) is sometimes used to determine how much fuel the injectors should add to the engine. if you've got a vacuum leak, the computer tells the injectors to add more fuel.

this has the same effect as applying a greater throttle opening: the throttle is just a valve to regulate how much air the engine gets. if you've got a vacuum leak, more air is being added on the downstream side of the throttle (closer to the engine).

you can often check for this IF your spark plug wires are in great shape and sealed at the plugs and the distributor, and at the coil, etc. In essence, you don't want anywhere a spark could get to gas or vapor.

with the engine idling, spray some starter fluid around the ends of the vacuum hose and listen to the engine (or have someone observe the tachometer, if you've got one). if the engine speed changes (more than the normal variability), you've got a leak.

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Answer 2

Sounds like the forward clutch(auto trans) or low one way clutch(auto trans) is slipping.

Try checking the trans fluid level, color and smell. If your vacuum line was soft and swollen and had mineral oil in it the modulator on your transmission may have a leaky diaphram.

Transmission fluid messes up vacuum hoses like there's no tomorrow.

If your new vacuum hose doesn't have a good tight fit and leaks in air I would cause a high idle but it wouldn't only be in drive.

If your veh. has a vacuum switch on the column which automatically releases the park brake when you shift into drive, and that circuit failed it could do something like that sorta.

No, I bet your low on transmission fluid.
modulator leaking into vacuum system.
$40, I accept visa, master card, discover, but i much prefer cash.

Answer 3

Clutch slipping????