Greetings,

I worked on my 01 discovery with 101,000 miles and did the full list from Mike's, Major Service posting. It toke a few days and a few hundred dollars but got it complete with no problems Also, changed the crank sensor and both front 02's, since it came to a stop and would not start again (it fixed that problem!).

Before the service I was having a misfire and thought after I did the major service it would fix the problem. I did put on Magnacor 8mm plug wires ($112.00 later) and Bosch Platinum Plus 4's plugs. I made sure that all wires got on the coil right and got plug in all the way, I know this isn't the problem. I am still getting codes P0306 and P0300. misfire in #6 Is this a common problem? Could it be the coil pack? Is there a easy way to fine out whats going on? Any suggestions would be great. Thank you for all you guys that help each other out!

 

Generally it would be more than just 1 cylinder if it were the coil pack, as they run 4 per pack. I suppose anything is possible though. I just wouldn't rush directly to the coils.

 

Do you have any coolant loss? I'm thinking an internally leaking head gasket. If you pull the dipstick do you see "milkshake" substance?

 

No coolant loss and the oil is looks like oil, no milkshake. So I think for now the head gasket is good. My next guess would be a fuel injector?

 

Scott, if you had an injector issue you would get a 206 code.
Number 6 pops up probably more then any other cylinder.
You could have a coil at your mileage, but jump into it yet.
If it were mine I would do a compression test to make sure the valve train is good.

 

I had same codes after I changed the front O2's. Double check you have the O2 connectors pushed all the way in. It looked like I had them all the way in but they were not. I guess because of the tight area they are located. So I gave the connectors one more huge squeeze and I felt a click. Cleared codes and never came back runs perfect.

 

Check your spark plug boots. If they have dry-looking or discolored spots, the plug wire broke inside the boot. This can happen during installation or removal if the boots are not pushed/pulled gently on/off the spark plug. The "wire" inside is really a delicate carbon-fiber material.

When that happens, the spark will arc through the boot into the engine block, cooking the plug boot in the process.

My Disco had a brand new set of plug wires on it when I bought it, but was mis-firing pretty badly. Couldn't figure it out for the longest time, it took a while for the plug boot show signs of damage.

New plug boots are about $2 each at NAPA, get the long orange ones. Carefully strip back the insulation, then crimp the new boot over the carbon fiber piece. There's not a lot of extra plug wire, so only trim back as little as possible to make sure it still fits with the new boot.

Good luck.

-Tim

 

Hey guys, I know its been awhile since I posted this. However, I wanted to let everyone I put on 2 new coil packs and the #6 misfire was fixed! I removed the upper intake manifold (to get to the coil packs easier) and when the manifold was off I put a new heat plat on, put 2 new gaskets on the rocker covers to fix a oil leak, torque the lower intake to make sure it was tight, oil change, and topped off everything. Wanted to give a update in case someone in the future reads this and has the same problem. It runs like new now!