Another Misfire on Cylinder 6
 

So, I just picked up a 1999 Disco 2 a couple of weeks ago. The seller was a REALLY cool guy and agreed to hold it for over a week to sell it to me, even though he had others that were interested. Just a great experience, overall from a guy who had never met me and lived almost 3 hours away. Everything seemed great when I finally drove it and I picked it up.

After picking it up, I put roughly 900 miles on it in the first week of owning the truck. On about mile 600, (after taking it off road in some pretty intense stuff) the SES light kicked on. Cylinder 6 misfire, running too lean, and MAF sensor. I cleaned the MAF and I haven't had that problem since. I changed the #6 plug with #2 and the misfire didn't follow. Now, I'm only getting the Cyl 6 misfire.

I contacted the seller to find out about the history and he says the plugs and wires are about 20k miles old and the injectors were "rebuilt", adjusted and checked around the same time by a reputable Rover shop in the area. They did all of this at the same time as new heads, power steering, radiator, etc...

I've ordered some coil packs from The Car Farm and was planning on doing the plug wires and plugs, just to be safe when I got another email from the seller. Here is what he had to say:

"I drove by my old Rover shop and talked with them. They said that the Rovers have an issue with a cylinder losing compression due to a "collapsed ring", or in normal terms, the ring sticks in the piston groove and does not seat against the cylinder walls. He said that this could cause the misfire, he said he would pour in a can of engine restore into the oil and run it for a couple days. This should/might make the ring come free and reseat."

We drove the Disco about another 500 miles for a family trip, this weekend. Around 250 miles from home, I got his message and followed these instructions and the SES light turned off after about 75 miles. It kicked on again for about 50 miles and then turned off again. I've since put another 100 or so miles on it and the light has been off ever since.

Is this too good to be true? Is this common knowledge? I've looked and looked and haven't come across anything about using Engine Restore to help with a misfire.

I'll be waiting to see what happens, but I figured I'd pose the question to get y'all's opinion on the topic. It sure would be nice if this would work for me. If nothing else, it will hopefully add another option for those Googling the topic sometime in the future.

this sounds like a liner. If the liner slips it will let coolant into the cylinder. The coolant will not ignite and that gives you the misfire.

It could be a pile of other things but...

Do You get a flashing check engine light when you start the truck in the morning?

No, it's a solid light. It only flashes from time to time after pulling a hill or under heavy load. Aside from that, when it's on, it's solid.

What do you mean liner? I haven't come across that in my reading yet. This is my first experience with these trucks.

Thanks!

I should also mention that it runs smoothly, it's just throwing codes.

Its rare to have a liner issue on a 99 4.0l. If a liner is slipping you will hear a tapping noise and it usually happens after truck reaches operating temps. I highly doubt this is your issue, if the head gasket is failing on cylinder 6 you could have just enough coolant mixture in the cylinder to not allow it to fire. Have you pulled the plug? Lots of things can cause a misfire. Don't go pouring crap into your motor without checking all possible causes first. If he put cheap wires or plugs in they could have easily failed and that could be your problem. Do you understand what i am getting at?

Good. I've also read that these trucks use a 'wasted spark' system. I'll be moving the #1 spark plug to see if the code follows.

Thanks for the help.

Your welcome

Yeah, I totally see what you're getting at. The only reason I tried the additive was because it was recommended by a reputable shop. I've got coil packs coming and I'll be ordering plugs and wires, probably tonight. I'm about to put another 100 miles on it right now, so we'll see if the light comes back on.

Yup. Misfire's back.

The plug wires are blue, so I'm not sure which brand they are, but all work was done by a reputable shop in the Portland, OR area. The previous owner also spared no expense getting things done right, so I'd assume that they used quality plugs. I'll take note when I remove the cylinder 1 plug tomorrow.

was the crank positon sensor ever replaced?