i have a 92 automic 4.0 liter and its running pretty rough. it smokes a lot but mainly just burning oil and it doesnt have a lot of power. also if you get on the gas pretty quick it hesitates and sputters. and for the main problem, after i get over 45 mph and i give it any gas the whole car starts to shake. i have replaced everything that i can think of...spark plugs, spark plug wires, checked all of the injectors, distributer, oil air transmission and fuel filters, entire new exhaust system, i changed the oil and used fuel injection cleaners (stp and sea foam). i have no ideas left. please helpppp!

 

i would do a compression check sounds like a misfire caused by mechanical damage (burned valve?)

 

yea it definitely feels like its misfiring. but would that cause the shaking at speeds only above 45 mph? and only when i give it gas?

 

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well if the shaking is violent then it's called the ''Deth Wobble''. What are your xj's spaecs? how much lift, tire size what front end upgrades do you have?
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Lets see, on my first one the death wobble was cured with an alignment. On my last one nothing fixed it even after changing everything exept the axles. So sometimes it's hit and miss.
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The main things to look at are 1.) Your track bar 2.) steering stabalizer 3.) shocks 4.) check all your bushings 5.) check that your tires are balanced properly 6.) make sure your wheels are not bent 7.) check your ball joints for up-down play 8.) get an alignment
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there you go thats my .02 . I hope it helps

 

I would do what they say ^, and i'd check your motor mounts just for the heck of it

 

well i have had the death wobble before and this is nothing compared to that. it feels like it is in the engine or pssibly the transmission. but i have 3 inch coils and leafs and 2 inch spacers and shackles, also a tc drop kit, drop pitman arm, adj. trac bar, steering stabalizer and new schocks. i think thats it

 

also it only does it when i press the gas above 45 mph. if i let off the gas the shaking stops and also if i give it more gas to go to the next gear it smoothes out. so it only really does it when it is under a heavy load i guess. once i give it more gas or let off it stops

 

Sounds like a fuel issue to me.

 

Mine had a really really horrible vibration at 50mph that turned out to be caused by a trashed wheel.

 

I just got brand new wheels and it wAs doing itbefore I got those. Do uthinnk it could be the fuel pump?

 

I had a colapsed tranny mount that resulted in my driveshafts not sitting correctly and it created lots of vibrations and noise at highway speeds...these were amplified if I had a load also. Replacing the mount pulled everything tight and there was no damage...replacing the fluid in the diffs gave me piece of mind too.

 

Mine did something similar and it ended up the crank position sensor, the wires were going bad and it was loosing connection causing the jeep to shake violently. I thought it was fuel related too until I tested everything and replaced, the pressure regulator, fuel pump, fuel filter and cleaned the injectors and none of that helped. If it's a death wobble make sure all your control arm bushing are good along with what has already been said. If it runs like poop try spraying combustion cleaner down the throttle body, its like 6 bucks a can from the dealer only. I've had to do that a couple times to free up sticky valves and get the motor to smooth out, its like sea foam but supposedly it doesn't come off in chunks it dissolves it more.

 

I don't think this issue has anything to do with the death wobble. If it was suspension related it would do it all the time at 45-50+ not when only he pushes the gas pedal. It's almost garunteed fuel related. It could be the cps but I highly doubt it.

 

I bought a 98 Jeep Cherokee XJ about four months ago I did the front brakes rear horseshoes brake fluid I also did the water pump thermostat water outlet all hoses I’ve done a lot of work to it too much to name but whenever I get on the freeway at 45 miles an hour at 2000 RPM’s my **** shakes like crazy and I know it’s not death wobbles I promise you. The motor mounts on my Jeep Are new I’m going to change them out but I did them 4 months ago.. I’m not skipping but my motor feels like it’s going to shake out

 

Did you ever figure out what it was? I also have a 98 and I have the exact same problem. I haven’t pulled anything out yet. This would save me a lot of time.