rctrucker2010

Hey guys I have a 00 cherokee sport (new toy/dd) I have a cylinder six misfire that's bad engine light is flashing sometimes and it surges sometimes. It's blowing some smoke can't really figure what color but it stinks bad. Any ideas on what to look at first or what it could be. Thanks guys

tjwalker

The flashing check engine light indicates a serious misfire, which if ignored, will trash your catalytic converter. Gotta resolve this ASAP.

Simple stuff first. Always. Start with fresh spark plugs. For the 00-01, I recommend NGK copper plugs. Be sure to verify gap is at .035 before installing. Also inspect and be sure that the coil to plug contact is solid and not compromised.

If new plugs doesn't help, try swapping the fuel injector from cylinder 6 to a different cylinder and see if the misfire follows. The "swap and follow" strategy is one of my favorite techniques.

Still stuck after this? Perform a compression test on all cylinders and see where cylinder 6 sits in comparison to the others. If any cylinders read low, add a tablespoon of oil to the cylinder and perform the compression test again. The compression spec for the 4.0 is 120-150 psi, with no more than a 30 psi variation between cylinders.

Good luck and keep us updated!

rctrucker2010

Ok thanks so much I will try that and go from there. As of now the jeep is sitting I have to get e check done before i can put plates on it.

rctrucker2010

We'll I was out messing with it and decided to check my oil looks like coolant is mixing but hard to tell if it's a head gasket could it still only misfire on six that's the only code when I ran light last night

tjwalker

The factory 0331 head on your XJ has a casting defect between cylinders 3-4 but there is always potential for any head or head gasket to fail at any point.

If you have a milky oil on your oil fill cap or dipstick, it's time for more testing. A compression test is the best test for a blown head gasket. A "block test" where they sniff the coolant for the presence of hydrocarbons (oil) is another test.

Keep checking codes, erasing them and see what sticks for more clues. Good luck.

rctrucker2010

Only code that came back was six again p0306 and it's a moly color on dipstick. I have to wait till Friday for compression test but I'm hoping it's just gaskets causing this mess. It only has 185 k miles on it

rctrucker2010

rctrucker2010

Ok so today I did a vacuum test today and it jumped like crazy so now I have to rip head off and see what's going on

rctrucker2010

Ok guys I figured it out. It was the cam shaft and lifter causing the misfire











Here's the pics

Kalali

First and foremost thanks for reporting back. So did you just discover that by visual inspection? And how did the the head look? Did you confirm a crack in the usual spot?
Thanks again.

rctrucker2010

Head looks great we noticed the lifted was acting different from the others so we tore into it more and found that so new cam from dealer and lifters all gaskets new timing chains should be up and going tomorrow. No cracks the we seen

rctrucker2010

We'll guys she back on the road after new cam and lifters and a bunch if other things but she's running great

rctrucker2010

Thanks for the help guys again it's running great except for my electrical issue which I started a new thread on check it out it's titled electrical issues causing motor to stall if anyone knows electrical issues please read that post all help is greatly appreciated