dano72

I just bought a 99 XJ, and it is my first Jeep. I have just got done going through fluids & seals etc. I switched out the injectors, and I dont recall if there was a slight miss at idle or if it idled smooth. There is one now.I am used to v8s where there is a slight shimmy every few seconds. THere is a slight vibration at idle I can feel in the steering wheel. It does not carry through as I accelerate or rev it up. Seems like a very slight miss, maybe a ignition issue. I did not switch out cap/rotor/plugs, but I inspected an it appeared to be in good shape. I cleaned off some corrosion from the cap contacts. Or is it the new injectors (new style). Perhaps it is a trait of these engines that I am not used to. Any insight would help.

kbeam418

Inspect the motor mounts. Start the engine and look at the engine if you see the motor shaking it's the motor mounts.

dano72

I just replaced the motor & trans mount???

kbeam418

If there's no codes I wouldn't worry about it. These old Jeeps were never known for being comfortable cars. I actually have to get used to mine after I drive my Grand Marquis because it's whole different animal .

tjwalker

Visual inspection won't cut it for tuneup parts. There can be micro cracks in the distributor cap, plug insulator, etc.

Perform a FULL tuneup. Champion plugs gapped to .035, quality plug wires, cap and rotor. Don't buy cheap tuneup parts.

This is a new to you vehicle so getting that full tuneup is not that expensive and will establish a proper baseline for future tuneups.

Good luck and enjoy your 99!

EZEARL

Should do this to:
http://cruiser54.com/?p=60

tjwalker

Absolutely, Earl....good catch. I helped Cruiser with this writeup.

EZEARL

Good going!

Morat

A straight six should be silky smooth, but having said that mine does miss/shimmy every 4-5 seconds and always has done. I suspect leads too (it has had a new distributor cap recently).
I did the IAC a while back, it helped.

dano72

Yes, it drives fine, it just seems to feel like slight cam lobe at idle.

kcdt58

My 2000 is the exact same way. I have new plugs, verified the coil pack is free of corrosion, cleaned the throttle body and IAC, checked and clean all grounds that I could find and it still does it. Driving down the road it runs beautifully, just a slight hiccup at idle.