93 YJ stumble

[knuckles06]

93 YJ, 4.0, 5 speed
The problems is it has a stumble problem. At low speeds it will start to jump like it lost fuel. I can make it do it also by hand by taking it to around 3000 rpm and back off slow. You can drive at speed with no problem I think I can still feel a stumble in it. But I had it on the interstate this weekend and run 90 mph no problem. I have changed the plugs and wires, disribitor and rotor, Fuel pump and fuel filter. I have check the coil and it's to specs. Fuel pressure is to specs. It did it before I changed the parts listed and it's still doing it.

[fredjacksonsan]

Have you cleaned the intake/throttle body? Dirt in there can cause intermittent stumbling.

[copperyj]

When the engine cuts out, does the tach needle drop real fast? That's what my YJ did. I ended up changing the Crankshaft Position Sensor. Napa had it for around $62. That took care of my issues.

[knuckles06]

Cleaned injectors and air intake. Changed Crankshaft Position Sensor still no change....

[fredjacksonsan]

Assuming you have replaced plugs/cap/rotor. Next thing I would suspect is the throttle position sensor.

[knuckles06]

Changed the throttle position sensor that fixed the problem.

[fredjacksonsan]

Sweet!