Finally assembled my 2000 LR Disco II after having it apart for close to 3 weeks. Had a valve job done by a engine shop. Had to get one head cause it was cracked. All 8 exhaust valves were replaced, 7 guides were sleeved, head machined, and pressure tested. Double checked the distance from the spring seat to the top of the valve stem and they were all within 1.74 to 1.8 inches. Cost for the valve job including cost of a replacement head and valves, $ 807. On starting, the engine ran rough, and was not able to idle. The RPM slowed down until it stopped. 2 codes came up P0301 and P0302 (cylinder 1 and 2 misfire). After idling for about 35 minutes with me at the throttle to keep the RPM from dropping and stopping, it now idles on its own.
Still a little rough but I'm down to one code (P0302). Took it for a spin. Smooth at higher RPM. I checked for vacuum leaks, I think I got them all.
PS. Had the battery disconnected all that time.
Any thoughts? Do I have do anything to the fuel rail (like bleed the air).
Ed

 

That 302 code, # 2 cylinder misfire is your rough idle.
With the battery unhooked that long the ECU will need to go thru a releaarning process over the next full tank of gas.
Mike

 

Mike
Thanks for the response. At first I thought it was the fuel rail having an air bubble ( since some fuel drained from there during the process of moving it ). Then I noticed it started to idle a little better, in not stalling, but the RPM was a little low. Now seems like the RPM is about 800 to 850 (about where it used to be). Retrospectively, it is getting better, which is consistent with the ECU relearning.
If I had to do it over, I definitely would make sure the fuel rail it topped up with filtered fuel and without bubbles, cap it, remove the cap only immediately before reconnecting with the fuel line.
That head gasket change did it. No more white smoke while warming up. You hit the nail on the head.
P.S. Will post a picture of the crack in the head. Trying to figure out how to get a good close up of it.
Ed

 

Ed,
The fuel system is self priming and a flow thru system, once primed and started, if there was any air in the system it would be pumped back into the fuel tank before you could put it in drive.
Check that #2 plug and wire.
Mike

 

Mike
Will do. Thanks
Ed

 

Hi Mike
The LR idles about 90% better than it did. Upon starting, the MIL that was on the last time, extinguished. Came back on a little later, however, it is idling a lot better. I still believe that I have some air in the fuel rail that I have unintentionally introduced while I was turning the lower manifold every direction while I was checking the machined surfaces and cleaning them. The source of air did not come from the the fuel line. Why I say this is because, cylinders 1 and 2 have random misfire, codes 0300, 0301, and 0302. If you notice, with the LR on a flat surface, the fuel rail is a little higher in the front and lower in the back. Any air would tend to favor the higher side. This affects the front cylinders e.g. number 1 and 2 cylinders. The fuel rail is also a dead end, which means that the only way out is through the injectors. Thirdly, on acceleration, if there is air in the fuel rail, the fuel tends to slosh towards the back due to acceleration forces introducing air into the front injectors (cylinders 1 and 2). Granted the injectors and and the capacious design of the rail is such that the injectors draw fuel from the bottom of the rail thereby reducing the possibility of drawing air and the 50 lb/in square fuel pressure in the fuel rail wil lreduce the size of the air bubble in to 1/3 is size. In due time this problem will go away. However, I feel that steep uphill rapid acceleration will hasten the aspiration of air into the injectors and this problem will eventually disappear.
I like that no white smoke on warming up. I'm glad I went for the head gasket change. For a while, up until I had reassembled the engine, I was still a little edgy though because that could also be a "porosity" problem with coolant leaking around the liners into the cylinders but with the engine running and heating up, the expansion of the liner into the cylinder block and combustion pressures eliminates further ingress of coolant into the cylinders. Thank God it wasn't that problem. I was already researching a flanged top cylinder liner for the LR.
Wires and plugs are fine.
I'll update later.
Ed

 

Couldn't deal with the misfiring (codes 0300, 0301, and 0302). I took off the upper intake manifold, took out the coil and found a crack on the #4 boot by the coil. Bought a new set of wires, the last one only 8 months old. Bought a new set of coils too. Pulled the fuel rail, checked the resistance of the injectors and they are ok ( 14.8 Kohm ). Did not check the spray pattern. Cleaned the injectors, specially the filter. Cleaned the injector seats on the fuel rail and the lower intake manifold. Put in new O rings for the injectors, all 16 of them. After I put it all together, I still get 0302 MIL ( cyl # 2 misfire ). Idles a little rough. No hessitation, smooth on acceleration, and smooth at higher RPMs. To recap, here is what I got.
1. New head gasket and valve job.
2. New plugs.
3. New wires.
4. New coils.
5. Clean fuel rail, new O rings, good injector as tested by ohm meter.
I need fresh ideas. My thinking cap is running out of thoughts.
Hmm, maybe should have deliberately swapped positions of the injectors to see if my misfire will follow a specific injector.
Thanks,
Ed

 

Hi all.
Follow up on this 2000 LR Disco 2 following a valve job, head gasket change, new plugs and wires, cleaned fuel injectors, that idled rough but ran fine at higher RPM.
This LR alway threw a P0302 code.
The cause was a lower intake gasket leak into cylinder # 2.
Problem now resolved. Runs like a dream.

 

Glad to hear you got a handle on the problem, some learning experience.