Misfire 4.0(new member)
01-02-2013, 01:23 AM
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Misfire 4.0(new member)
Hey guys new member here. I have a 2000 Jeep cherokee 4x4 with the 4.0 a few months ago it was over heating so i took the head off and it was warped. my local mechanic shaved the head down and rebuilt it(he has done several others in the past and i never had a problem) so i put it all back together got the motor at top dead center and installed all the parts needed. when i fired it up it ran great for about 5 minutes then it started misfiring and it sounds like the rockers are knocking a little bit when the motor is reved up a bit. i went and put a code scanner on it and it comes up with the codes
-Multiple Cylinder Misfire
-Cylinder 3 Misfire
-Cylinder 5 Misfire
i drove it around the block thinking i may of had bad gas or something and when i was driving it the check engine light flashed a few times went off then 10 minutes later it flashed again and stayed on. I have replaced a few parts since its been misfiring and switched injector 1 and 2 with 3 and 5. i hooked noids up to the injector plug ins and those are all fine. i checked the compression on all 6 cylinders and they all around around 130.
Here are the things that i have replaced since it has been misfiring
-New Coil Pack
-New Auto Lite Spark Plugs.
Its been in my garage for about 3 weeks now and it has me pretty much stumped the only thing that i could think of doing would be check the fuel pressure. Hopfully one of you guys had a similar problem before and could help me out. Thanks Happy New Years!!!
-Multiple Cylinder Misfire
-Cylinder 3 Misfire
-Cylinder 5 Misfire
i drove it around the block thinking i may of had bad gas or something and when i was driving it the check engine light flashed a few times went off then 10 minutes later it flashed again and stayed on. I have replaced a few parts since its been misfiring and switched injector 1 and 2 with 3 and 5. i hooked noids up to the injector plug ins and those are all fine. i checked the compression on all 6 cylinders and they all around around 130.
Here are the things that i have replaced since it has been misfiring
-New Coil Pack
-New Auto Lite Spark Plugs.
Its been in my garage for about 3 weeks now and it has me pretty much stumped the only thing that i could think of doing would be check the fuel pressure. Hopfully one of you guys had a similar problem before and could help me out. Thanks Happy New Years!!!
Last edited by mattpiotr; 01-02-2013 at 01:26 AM.
01-02-2013, 01:29 AM
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Year: 2015, 2012
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Engine: 3.6L
Hello and welcome to Cherokee Forum. Nice looking Jeep.
Because of known head cracking problems with the 0331 head, especially on 2000 models, you might want to check the spark plugs on the affected cylinders for signs of coolant contamination/burning.
Even though your head was rebuilt, sometimes the cracks don't show up on a cold head sitting on the bench. Since it got hot enough to warp the head, that head is probably cracked now even if it wasn't before. They usually crack between #3 and #4 valve area.
Because of known head cracking problems with the 0331 head, especially on 2000 models, you might want to check the spark plugs on the affected cylinders for signs of coolant contamination/burning.
Even though your head was rebuilt, sometimes the cracks don't show up on a cold head sitting on the bench. Since it got hot enough to warp the head, that head is probably cracked now even if it wasn't before. They usually crack between #3 and #4 valve area.
Last edited by Firestorm500; 01-02-2013 at 01:32 AM.
01-02-2013, 01:38 AM
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Hello and welcome to Cherokee Forum. Nice looking Jeep.
Because of known head cracking problems with the 0331 head, especially on 2000 models, you might want to check the spark plugs on the affected cylinders for signs of coolant contamination/burning.
Even though your head was rebuilt, sometimes the cracks don't show up on a cold head sitting on the bench. Since it got hot enough to warp the head, that head is probably cracked now even if it wasn't before. They usually crack between #3 and #4 valve area.
Because of known head cracking problems with the 0331 head, especially on 2000 models, you might want to check the spark plugs on the affected cylinders for signs of coolant contamination/burning.
Even though your head was rebuilt, sometimes the cracks don't show up on a cold head sitting on the bench. Since it got hot enough to warp the head, that head is probably cracked now even if it wasn't before. They usually crack between #3 and #4 valve area.
01-02-2013, 01:41 AM
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Year: 2015, 2012
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I don't guess you've driven it enough to notice if it is using coolant or not.
Also, since you put in new plugs they may still be all the same color. So discoloration would be hard to spot.
Also, since you put in new plugs they may still be all the same color. So discoloration would be hard to spot.
Last edited by Firestorm500; 01-02-2013 at 01:47 AM.
01-02-2013, 01:57 AM
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Yeah it has not been going through coolant or anything i ve been checking that ive been letting it ideal here or there lately but all the plugs still look new like you said need to run it a bit more
01-02-2013, 09:56 AM
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Couple questions:
Do you have a 2000 Factory Service Manual?
Did you use a calibrated torque wrench when you torqued the cylinder head bolts? When you torqued the rocker arms cap scews?
You said the local mechanc rebuilt the cylinder heads. What all did he do to the head when rebuilding it? Replace valve springs? Valves? Talk to him and find out what he did.
I'm sure you were careful when doing all that head work but...
Make sure the Oxygen Sensors and wiring are secure and undamaged.
You said: "and it sounds like the rockers are knocking a little bit when the motor is reved up a bit"
You may want to remove the valve cover and double check the torque on the rocker arms cap scews (21 ft. lbs), check each valve spring locks to make sure they are there and properly seated in the spring retainers, check the valve springs for movement side-to-side, check each rocker arm lash (zero movement up and down when rocking them and the respective valves at the base circle of the camshaft.**), and make sure the push rods are properly installed.
** Put #1 cylinder at TDC compression, and vibration dampener index mark at the "0" mark on the timing chain cover timing marks. Check rockers at cylinders 1 and 6, rotate the vibration dampener clockwise 120 degrees and check cylinders 5 and 2, rotate the dampener another 120 degrees and check cylinders 3 and 4.
Check for a crack or cracks in the cylinder head between the rockers for cylinder 3 and 4.
Do you have a 2000 Factory Service Manual?
Did you use a calibrated torque wrench when you torqued the cylinder head bolts? When you torqued the rocker arms cap scews?
You said the local mechanc rebuilt the cylinder heads. What all did he do to the head when rebuilding it? Replace valve springs? Valves? Talk to him and find out what he did.
I'm sure you were careful when doing all that head work but...
Make sure the Oxygen Sensors and wiring are secure and undamaged.
You said: "and it sounds like the rockers are knocking a little bit when the motor is reved up a bit"
You may want to remove the valve cover and double check the torque on the rocker arms cap scews (21 ft. lbs), check each valve spring locks to make sure they are there and properly seated in the spring retainers, check the valve springs for movement side-to-side, check each rocker arm lash (zero movement up and down when rocking them and the respective valves at the base circle of the camshaft.**), and make sure the push rods are properly installed.
** Put #1 cylinder at TDC compression, and vibration dampener index mark at the "0" mark on the timing chain cover timing marks. Check rockers at cylinders 1 and 6, rotate the vibration dampener clockwise 120 degrees and check cylinders 5 and 2, rotate the dampener another 120 degrees and check cylinders 3 and 4.
Check for a crack or cracks in the cylinder head between the rockers for cylinder 3 and 4.
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