rough idle and shaking? Are they related?

my wife has a 2001 jeep cherokee 4.0 2wd it began idling rough. I ran codes im getting cylinder 6 misfire. It also started shaking but the shake is only when accelerating and then begins to shake like the tires are bad in the rear steering wheel does not shake at all. But the ierd thing is it begins shaking only when the transmission shifts into what ever gear it is in at 45 mph.

I searched and cant find the two things related unless I have completly missed something. And these started happening at the same time.

Tire check they are fine. No low oil pressure. No high temps or overheating. does not feel as if it is going to stall. No play in driveshaft.

Any ideas

You could have more than one problem going on here.....The shaking could be any number of things. What you're describing could be a transmission mount. I would crawl under it and yank on everything to see if there's any play or any sign of worn components.

Does the rough idle happen after you've run it and the engine is hot? If so, you'd want to search "Heat soak," get some coffee and read up. I suppose you could swap injectors and see if the misfire follows the injector. That might help you diagnose it if its not a heat soak type of situation. When were the basics done last like spark plugs and wires? Your 2001 is disbributorless so no cap or rotor to mess with.

When you have a code, you MUST chase that code.

Cylinder 6 misfire:

1. Replace plugs. Stay away from Bosch. NGK is a great choice for the 00-01

2. Still misfiring? Swap #6 injector with a different cylinder and see if the misfire follows to the cylinder with the suspect injector.

3. Still misfiring? Compression test to rule out something internal

4. Coil rail and connections also still in play here.

If it had plug wires I would swap plug wires first.

Pull the #6 plug and see what it looks like!!!! Consider swapping 2 plugs if #6 looks good, or they are all well used.....replace the plugs.

o have the same xj, i rebuild the engine, and now I have a terrible engine shaking, but when i get up to 2500 rpm shake goes away, all this in parking gear

XJBLACK,

Some additional things to try:

1.For the vibration: When driveshaft U-joints go bad, they vibrate at some speed because of excessive play in the bearings.. With engine OFF, get under the car and hold a U-joint with one hand and the driveshaft with the other hand. Rotate driveshaft back and forth to see if you have any play in that U-joint. Do this for both U-joints on each end of the driveshaft. If there's any play in either U-joint bearing, replace ALL U-joints.
2. Misfiring cylinder: Check that each injector wire has the proper colored wire attached to it. If an injector has the wrong color wire attached; it is not being fired in the right sequence. If there's no fuel in a cylinder when the spark plug fires, there is no combustion in that cylinder. Likewise if your XJ is like my 00XJ, it has no plug wires, just a spark plug rail/ bracket that snaps over all spark plug terminals. Remove the spark plug rail/bracket and pull the spark plugs and check them. Then smear dielectric grease into every plug terminal connector (on the spark plug rail) and reattach the rail to the spark plugs and try. If its still misfiring, you may need a new spark plug rail/bracket for the spark plugs. Finally, look for intake manifold vacuum leaks with a vacuum gauge.

Best regards,

CJR

vimoto said:

o have the same xj, i rebuild the engine, and now I have a terrible engine shaking, but when i get up to 2500 rpm shake goes away, all this in parking gear

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What year is the system, the ECU/PCM controls, and engine.