I own a JK 2007 V6 3.8 (65,000 miles) and I have a weird problem.
When I start the Jeep the check engine light turns on, when the gear is in N (or P) engine runs smooth throughout the RPM. Between 1500-2000RPM (while driving) 3 cylinders don't work (#1, #3 and #5) and check engine light starts blinking. After driving a few minutes on only 3 cylinders, when going over 2,000 RPM the rest start working again and the check engine light becomes steady, if I go below 2k it starts blinking again and running on only 3 cylinders.

I've been to the garage, they tried connecting it to the computer but all the readings come out OK.
I could really use some help figuring this out...

Thanks,
Amir

 

Any chance you can get this to a dealership to have them take a look? This might be worth paying a few dollars to have them run some diagnostics. If you have a check engine light on they should be able to pull the codes. My understanding is if it's a solid light, you can drive it, but it needs attention. If the check engine light is flashing, then it's more serious and it needs immediate attention. You might want to give them a call before you drive it more. I know this probably isn't the solution you are looking for, but I would hate to see you cause any potential damage.

 

I have been to the dealership, but they can't find the problem...
They ran diagnostics while driving, thats how we know 3 cylinders aren't working but when standing the diagnostic tool shows no problem.
The problem is we can't figure out why 3 cylinders aren't working.

 

OK they are all in the same head how about ignition or fuel delivery?

 

Has to be something common to the odd numbered cylinders like the coil pack for that side. I haven't really done much more than preventative maintenance to this engine, but I wonder if you can swap the coils.

 

These 3 cyl. are in the same head

This engine has 3 coil for cyl/ 1+2 cyl. 3+4 and cyl. 5+6 but the problem is in cyl. 1-3-5 .

?????

 

It has three coils, all in one assembly, but the commonality is as follows:

1 + 4
2 + 5
3 + 6
The firing order is 1 2 3 4 5 6

Has the dealer determined if it's the ignition or fuel to those cylinders is turning off.


The 1, 3, and 5 plug wires run together to the right head.
Has anyone looked at those wires for damage, or checked their resistance?
Did the dealer pull the plugs and inspect them? Plugs can tell a story.

 

The wire are ok
We change to new plugs
If the wire were damage why only betwen 1,500 to 2,000 rpm ??

 

You have a rare fuel efficient jeep. Congratulations! Consider yourself lucky!

 

fuel delivery to that head. easy....tell them look at the fuel line, sounds like a crack there somewhere causing air to the system at accelleration. had the same thing happen to a snowmobile of mine. 14 trips to the dealer, found a hair line crack in a fuel hose causing it to suck air at higher rpm.