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I had a head crack, so i replaced it. All new gaskets, rebuilt head, new oil, coolant, etc. It all went back together good. Started it up and it had camshaft position sensor code. Strange because i never disconnected that sensor. I made sure it was plugged in all the way and the wires were ok, and cleared the code. Started it back up and it was gone, but it was still misfiring, almost wants to die at times. I replaced the plugs, thinking that may help....nope. Pulled the plugs back out and checked compression. 120 on all 6... Thank God! Everything is plugged in, i just cant seem to figure it out. Any ideas or secrets? I need all the help i can get, i'm worn out!!!
 

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It has a coil pack that has all the plug connections on it, so that cannot be it. As far as the rocker arm idea, I am sure I would hear it. I torqued all of them correctly...?
 

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Discussion Starter #4
If there is good compression on all cylinders, it couldn't be the rebuilt head could it?
 

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Is there an assembly that looks like a distributor with a flat cover on it?
This would be just forward of the oil filter. If so, it is possible that your cam and crank sensors are out of synch. Inside this assembly is a hall effect sensor which must be synched with the crank position sensor. You may need to find a shop with a two-way scanner to tell the computer to relearn the relationship between the two sensors.
 

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is there an assembly that looks like a distributor with a flat cover on it?
This would be just forward of the oil filter. If so, it is possible that your cam and crank sensors are out of synch. Inside this assembly is a hall effect sensor which must be synched with the crank position sensor. You may need to find a shop with a two-way scanner to tell the computer to relearn the relationship between the two sensors.
this
 

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Discussion Starter #9
Well I decided to take it down the street to see if it would pull a code, or get better. I couldnt get it over 45mph and the oil pressure was maxed out..? When I returned I used my IR thermometer and checked the exhaust manifold to determine which cylinder it was. Well they all varied, so I went under the jeep to shoot the cats. One of the cats was glowing red.... I am not sure about the oil pressure?

I will change both cats and post to let you guys know the outcome. I hope the cat had something to do with the oil pressure. Maybe it was causing a lot of back pressure in the engine?
 

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Cats could be coming apart and getting plugged up. I've seen the upper cats melt down.
Your oil pressure gauge is not really a gauge; it's more of an idiot light with a needle. It could be a voltage issue at the sending unit.
Take your jeep to a shop with a two way scanner and have them go in and check to make sure your cam and crank sensors are in synch and go from there. You still need to address that issue since it is what appeared first. Investigate...don't just throw parts at it hoping you'll fix it.
 

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The cat should have nothing to do with the oil pressure or your other problems. Like said before if your crank position sensor and your cam position sensor are off it can mess up a whole lot of things. Something could have got messed up during the swap to cause your timeing to be off.
 

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The late 4.0l cam sensor/oil pump drive assembly likes to seize up the bushings inside. Sometimes the gears break, and the Jeep dies, othertimes, it drags enough to slip and cause the sync to go out. Look at the base of the drive where the hold down clamp is, if the drive is starting to seize, the body usually will show fresh raw aluminum where the body rotated away from it's original clamped location

Check this first, as it can be causing all of the symptoms, including the burning up cat from the misfires.

If you set the engine to TDC #1, there is a hole in the bottom of the oil pump drive body that will line up with a hole in the reluctor inside the drive when it's at TDC#1. A replacement drive assembly will come with a plastic plug locking it at TDC#1. A 1/8" allen wrench or drill bit wiill work as a locating pin, too.

Hope this helps!
 

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This just reminded me of the "toothpick" method for timing.
Search for this [toothpick 4.0 jeep] and it may help.
Please post what you (or you mechanic) comes up with for a resolution.
J.B.
 
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