I have a 01 Disco II with about 118K on it. I have been having misfire issues and it seems to be getting worse. In the past few months I have changed to Platinum +4s and 8 mm Magnacores this weekend. Last week the misfire would be pretty rough and cause some shaking. My wife said today that the light came on but the car drove fine. She said it flashed then went solid which has been typical for the misfires. I have also done the Seafoam induction cleaning this summer. Since cylinder 8 and 5 are on the same coil pack is this the next logical step? Can the coils be taken out without taking the IM off? My brother did my wires for me without taking off the IM this weekend since I was traveling.

Thanks in advance for any suggestions/advice.
Joe

 

I had a similar problem on my 04 DII. Members here advised a head gasket issue. I replaced all the "usual" suspects for a misfire.. coil packs, wires, plugs, and injectors to no avail. I was "certain" it couldn't be a head gasket.. clean oil, and little or no coolant disappearing...but the coolant DID begin to disappear within a few weeks of the misfire...turned out to be a leaking valley pan gasket..directly into the cylinders that were misfiring..hence clean oil.. since I was there, I replaced the head gaskets, and indeed, one was leaking, but not into the oil, but outboard and down the back of the engine.. $400 DIY, 2K plus at the stealership.

 

Make sure you have no cross wires if not. Pull all the plugs out. Run a dry compression test. crank each cylinder the same amount of time 30 secs each. Write the #'s down a sheet of paper. This will tell you if the gasket between two cylinders is shot. Look at the plugs carefully + keep them in order it will help figure out the problem much faster. Does any look different? Can you check injection pulse?

 

I would do the coils next.

 

You can check the coil by placing a known good plug at the end of the wire hold it against the engine you will see the spark jump the gap.

 

Thanks for all of the advice. I changed out the coil pack without removing the intake manifold the other day, not fun but not impossible, it was a little easier than I thought once I figured out a few little tricks. Anyway, did a quick test drive and had a misfire on 5. Also, I should note that the head gaskets were done about a year ago. I picked up some techron to run through the tank to try and clean the injectors and another plug for number 5 and I am going to try that this weekend and try and do a compression test as well. My thought is maybe I fouled out the new plug as I started with the plugs, it went away for a while, then came back and I am where I am today with a new coil, wires, and the plugs I changed a few months back. I'll check the plug for coolant or anything else when I pull it out.

Also, I had read somewhere that when the crank sensor starts to go bad it could cause a misfire? It seems weird that it would always be on the same cylinder. And I would think that when the crank sensor goes it goes completely. Anyway, thanks again.

Joe

 

No, but a high end scanner should be able to read the coil outputs.
You may want to consider a compression test before you start throwing parts at it to make sure you don't have some valve issue.
8 and 5 are on the same coil, so it is possible they are failing, but test the compression first.

 

I agree compression would be the most logical next step. Make sure the coils are disabled. Pull all the pulgs out. Crank the same amount of time.

One more thing I came accross othen with this type of coil system on other car/trucks. The customer would often damage the NEW wires near the tip installing or pulling them off. Thus creating induction to adjacent wire. Do you own a Ohm meter? if not move the suspected wire to a different plug and spot on the coil. If the problem moves the wire is damaged inside even though it is new. I would check this first before going any further. It is easy to check and could save you time. I had multiple GMs cars towed in because of a bad misfire due to this. Good luck!

Arnold V

 

Sorry reading the thread once again start to finish. I also want to mention I often came accross cars not design to run 4 tip spark plugs running poor because this. It changes the spark timing thus creating a different flash point. I ran accross this on multiple Mercedes Benz and older BMW's when the customer was sold 4 tip plugs the engine managemt system was not design to understand them.( This was the final explanation I was given). Strangely Some cars even would run fine for weeks then start to act up. Once I replaced the plugs with the correct factory single tip the problem would go away. My own fathers S420 fell vic to this by a independeplug the MBZ shop out of State, his ran fine for a few weeks. Then it started acting up. I told him what to do and all was well. I know some will disagree with this. I lived it and saw it enough to mention it. I Even had a BMW 1989 R100Rt (Motorcycle Boxer engine) that would not run at all after the four tip plugs where installed by a customer. He did not know what to do he thought something else was wrong. I replaced the plugs with single tips and all was well. The auto supply store told him they would work better than the single tip plugs. I did'nt have many customer with Land Rovers mainly MBZ,BMW and fleet GM/ Ford.
Hope this helps.

Arnold V

 

Sorry to have to post this here...cannot find button to post a new thread and this is the closest thread I can find. This makes my quest twofold:
1. How do you post a new thread? I have spent in excess of an hour looking!
2. Is it possible for a coilpack on a DII to lose fire on only one post? Currently have no spark on cyl 8 only. Upgraded to Magnecores to no avail. I have tested with inline spark detector, and nothing on #8. Time for new coilpack?