Recently did a valve job ( heads done by an engine shop ) heads resurfaced, new head gasket, new coils, new wires, new plugs, had my injectors cleaned and flow tested. The engine stills throws out P0300, 0301, 0302, 1300 codes. The car has 99000 mi and is a 2000 MY Disco II. During the repair, I disconnected the battery for 2 weeks to wait or the heads to come back. I'm at a loss to figure out the cause of the misfire. The LR runs well with load and at high RPM. No backfire appparent. My misfires is most apparent at low engine speeds by idling a little rough.
Any ideas as to the cause?
Thanks
Ed

 

What brand of plugs and wires did you use?
Mike

 

I haven't had any of the work done to my truck that you have had, but a few months ago I had the same codes for misfire. I installed magnecore wires and some stock champ plugs. I still had some rough idle and intermittent misfire codes. I ended upchanging the MAF, cleared the codes and got a P0150 code for o2 sensor. changed trhat and the rough idle went away. no probs since. I have 93K on my DII

 

Hi Mike / Rob
Got Bosch Platinum Plus 4 and Magnecor 7mm wires.
Any chance I could have lost the info on the EPROM of the ECU by leaving the battery off for that long?
What puzzles me is that it idles rough, but absolutely no hessitation across the RPM spectrum, no backfires, no misfires on load, runs like a gem at higher RPM, great pick up on acceleration ( alot better than before I did the valve job ) except it idles lousier that before the valve job. Figure that one out, LOL.
Ed

 

Sounds strange to me too. When I had my misfire codes it would be more rough at a stop (in D) than say sitting in the driveway in park. My DII eventually started to die randomly and would not restart this lead to replacing the crankshaft position sensor. (CKS)
With the work you have had doen it seems like it should be running like new. How long has it been since you started driving it after it's been all back together. It may take a couple of drives to get the computer to get the right set up. It took me about 2-3 good daily drives to work and back to get mine running good after replacing the CKS, it was just a lil rough for the first couple of trips, then it was good to go.

 

robdis96
Just got it together last night. Drove it to work today.
Ed

 

robdis96
I'm starting to think it is my CKS for several reasons. First, the cars idle plenty rough for just one cylinder misfiring ( code P0302 ).
Secondly, when I took the engine apart, I didn't drain the coolant completely and subsequently had coolant all over the rear part of
engine when the heads came off. That's where the CKS is.
Anyway, how difficult was it to change?
Ed

 

So if I read this write, you have only one misfire code, 0302,?
When you mention the CKS, what are you referring to?
Mike

 

Hi Mike
Yeah, just that P0302 code.
By CKS, I mean the crankshaft sensor.
Its on the left rear side of the engine.
I'm sure it got drenched with lots of coolant fluid when I pulled the head off.
Ed

 

The coolant should not affect the crank shaft sensor and if it did it wouldn't throw misfires, it would be hard to start, stall or a complete no start.
Mike