2001 disco running like a horse all a sudden. here are the codes I am getting.


ECU DTC Description

12 P0300 Random Misfire Detected

12 P0306 Cylinder 6 Misfire Detected

12 P0306 Cylinder 6 Misfire Detected

12 P0303 Cylinder 3 Misfire Detected'

replaced Iridium spark plugs and wires in less than 20K. not sure what's going on.

I guess I will start with Spark plugs then work my way up.

Thanks

Sayeed

 

Start by testing each plug to make sure you have good spark (the cylinders with the codes are probably a good place to start). If you find some are not sparking then I would suspect you have a bad coil.

The same thing happened to me. The truck was running great when I parked and went into the store but when I started it to leave I had a few random misfires. I checked the cylinders that were misfiring for spark and found no spark at all. I replaced both coils and all was good. A coil can just die all of a sudden like you are describing.

 

The MAF can also cause crazy things like that to happen. If you know anyone with a well running disco swap the MAF and you'll instantly know whether that's the issue. Worked for me and I was getting random misfires and specific ones and rough running. I felt dumb because DiscoMike had told me to do that weeks before. It is also the easiest swap of the many possibilities you face.

 

OK put tester between Spark plugs and wires. looks like consistent good electricity. Took out spark plugs looks ok may be worn out a little. Going to replace with BoschPlatinum+4 Spark Plug (4418), will do a good clean up of the Air Intake, need to change Oil with Rotella 6 and Wix 51515. these needed to take care anyways. Let's see if that clears my problem. will report back later. Thanks

 

Ok, I dont mean to hijack this thread, but Roverguy, when you replaced the coils, could it be done with the intake in place? Thanks!

 

No you Can't. I changed the Spark plug wires before following some cleaver posts here. But it's impossible to replace coil. there is not enough space. Next time I will take the Intake off. just to make this simple.

 

Update. After this TLC (Spark plugs, Air filter, Oil change and a good cleaning of the MAF) Truck runs great. I am going to drive this week to see how smooth runs and stays that way - so this is a Good day!

I may change the MAF or order one in case. Anyone know where to get one reasonable. I see a lot of Cheapo ones on ebay.

ERR7171W MAFS $145 BOSCH (OEM) 99~02 Discovery Series II @ British Parts of Utah-Land Range Rover Sport LR4 LR3 LR2 Discovery Defender Freelander Genuine OEM Accessories Parts

 

I know this will make me unpopular but I've been using an Amazon cheapie MAF for two years with no issues. About 35 bucks shipped.

 

Messing with my coils required me to take my intake off, which boogered the upper intake gasket. The next time, I took the motor mounts off and lowered the engine because I didn't have a spare upper intake gasket. It works but it is much easier to wait several days for an intake gasket and remove the upper intake than lowering the engine.

 

As others have already mentioned, the upper intake should come off to change the coils. Order a new upper intake gasket to replace the old one. They are a one and done type of gasket.

Here is the link to the gasket- Land Rover Intake Manifold Gasket (Same Fit As Genuine Part # ERR6621) - Land Rover Engine Parts