OK so here is the story. I just bought a 03 Disco II with over 200,000 miles for $1500. It's a combination, labor of love project for my wife to drive around and a personal challenge to see if I can fix it. I have a relatively comprehensive service history to include an engine replacement at 180K.

Now onto the problems.

I am getting engine codes:
p1300 O2 cycle fault
p0303 cyl 3 misfire
p0306 cyl 6 misfire
p0300 misfire on multiple cylinders

There is a chuffing sound coming from the right rear side of the engine. From what I've read that usually indicated head gaskets, however I don't have any coolant loss, steam cleaned pistons, coolant in the oil or exhaust. The previous owner thought this was the cause of all the misfire problems

I have an oil leak coming from the right rear of the engine and I know that it isn't the rear main seal. Once again from what I've read it seems to be the valley gasket leaking. It only leaks after the engine is turned on and warmed up a bit.

I have some oil in the throttle body but I'm not sure which vent hose it is coming from.

The spark plugs, wires and coil packs have been replaced by the previous owner in the last 2000 miles. I pulled the spark plugs and they all looked in decent enough condition, a little more carbon that I would have like to have seen on them but that might have come from excess fuel.

So there it is. I just wanted to get some insight before I started ordering parts and going to town with a wrench.

Oh and Hi it's nice to be on a car forum with more than 10 people.

 

Hg failure can be just a leak not nessesarily a mix. The exhaust sound ( chuff ) should be pinpointed, could be at manifold or out the hg. If hg the exhaust gas can groove the block or head.
Are you getting any oil leaks onto plugs? That too can foul. Valve covers can leak on them.
Gobble gobble

 

P0300
P0306
P0303

Most of the the misfires means the spark isn't occurring properly P0300 is just confirming it is happening in multiple cylinders. Since the misfires are happening on both of the engine, I would think electrical. So what has happened recently that could be causing the issue.

You said the previous owner did the coils plugs and wires in the last 2000 miles. My first guess would be that this job wasn't don't right. So either the plugs are bad, the wires are bad or the coil is bad.

Since your doing all that, you might as well compression check the cylinders while you test each plug.

Dusty likes to crank the engine and hold the plug to his tongue while someone turns the Key. I don't recommend that.

 

well do it the sissy way... I won't judge

 

Well did my compression test and cylinders 2,5 and 6 all read about 0 psi. So yup I guess that would be the cause of my issues.

 

That seems odd to me. I wouldn't expect three non-adjacent cylinders to lose compression. Also, you had a misfire in cylinder 3, but it has compression?

 

My mistake I meant 3 not 2. Ordered a head gasket kit and head bolts today. Hopefully I can fix it this coming weekend.

 

Godspeed . All will work out great

 

Thank you. I'll be updating with pictures and if it works out and fixes my problems

 

How did you make out? I am having the same misfire issues and I have done new plugs, wires and O2 sensor. I am wondering if this is my next step. Thanks.