I have a 2001 jeep grand cherokee 4.7l my problems all started with a knock hesitation & rough did self diagnosis & came up with p1391 p0307 & p0357 what does each one mean for that year make & model i change the coil pack & the knock came back???? & these codes are what came up what should i do

SOURCE: Jeep Hesitates. P0303 code

Check the cylinders Commpression. over 115 psi is good, 120 psi is normal.

SOURCE: 2001 Jeep Grand Cherokee code P1391

I would check to be sure that the timing chain hasn't jumped at all ..

SOURCE: multiple misfire 2001 jeep grand cherokee

would recommend a compression check be carried out as you may have internal mechanical problems

SOURCE: I have a 2001 Jeep Grand Cherokee and my check

could be a crank or cam sensor beginning to fail, or a bad harness connection at either. Usually though you would feel a problem there as both are necessary to keep the engine running.

SOURCE: 2001 Jeep grand cherokee motor knock 4.7 motor

First, if the noise is from the upper part of the engine and is more of a tapping than a knock, likely you have a problem in the valvetrain, most often a bad lifter or worn rocker arm. If the noise is low, deep inside, the noise is from a bearing. This is generally accompanied by lower than normal oil pressure. Regardless of the underlying cause, correcting the cause will not stop the knock. To do that correctly, the engine needs to be removed and all crankshaft bearings and the crankshaft itself need to be replaced (crank can sometimes be "undercut" and thicker bearing shells can be used depending upon the amount of wear.) If caught very early, sometimes only one bearing can be replaced in-car, but in 99% of all cases I have ever seen, most will fail again, sometimes more severely if done this way.

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