frankrizzo
NAXJA Forum User
- Location
- illinois
ok so i have a 99 4.0 with 114k miles on it that ive had for the past year and a half. when i bought it it had an engine vibration at idle that is still bugging me. so piece by piece ive been attacking it with parts. it starts right up, has never died out on me nor does it burn oil or coolant. it has good power and runs good once i give it gas in any gear but at idle it has this shaky feeling , kinda like an intermitent misfire and you can see the needle shake just slightly. it has new champion plugs, plug wires, cap, rotor, msd ignition coil, new elbows and lines, battery, cold air intake thermostat, and other non engine related parts like water pump and radiator. ive also cleaned the throttle body and the IAC. but the shake is still there. it does it only at idle wether im in park gear or neutral. i was thinking O2 sensor but from what i understand they dont do anyhting when you first turn the vehicle on (does it then also). could it be a CPS? a bad harmonic balancer? i also did the 784 injectors but that did nothing. even seafoam did nothing. any ideas. no check engine light on and no pending codes. if it helps out when i turn off the jeep, as i turn the key to shut off, the motor will shake for a half second as it shuts off. thanks