Driving now. I was getting the flashing ses, driving uphill, and erased the codes. Again, as soon as the light disappeared the engine sorted out.

 

I read and re-read this a few times to try and understand what is going on. If I am reading everything correctly, you are getting misfires that clear up as soon as you clear the codes.

If that is correct is sounds like the computer is changing something (air, fuel, spark, something) and when you clear the codes it is returning to a factory setting for a while before detecting the problem again. It looks like you have replaced a lot of the common parts that could cause a misfire so that's good.

I suggest you do a fuel pressure test to make sure you are getting pressure.

Do a good smoke test and check for vacuum leaks.

Plugged up cats can be a problem too. FYI- If you don't have plugged cats yet you will if you keep driving with the misfires.

You mentioned you did a head gasket job. You should double check all the small things like, you didn't mix up injector plugs, pinch any wires, leave grounds loose, or leave a rag plugged in a hole somewhere (It happens).

 

Those are all good suggestions. You are reading it correctly. When I erase the codes the change is instant.

The rag comment is funny... I did use a rag to plug the throttle body when I had it off and I was paranoid about leaving it. But I am sure I removed it. Lucky rag.

I did remove the wiring from the injectors. Maybe I should just replace the injectors.

Tonight I replaced the spark plug wires with new ones. Such a PITA with the manifold on. In any case, I immediately had the same misfire problem on 2468--the entire passenger side (but goes to more than one coil). I was super careful running the spark plug wires. I even zip tied them away from the block and each other. No small feat. I had a buddy with me who helped me be sure the coil/plug placement was right. He's my witness... I erased the codes and it ran like a scalded dog, immediately. Again, did this while driving so no change in conditions.

If I am going to take off the intake manifold (to check injectors) I might as well swap the coil with my spare.

This is really kicking my butt. Please keep suggestions coming.

Best,

Charlie V

 

Along with the misfires I always get the P1300 code. Is that significant?

 

I checked the ground strap and the ground to the battery. The strap was loose. I tightened it and drove... Same misfires. The battery ground was tight.

However, I removed the ground strap, started the engine, and tapped it to the bolt in the firewall. No spark. Should there be one?

Also, while it was running it threw codes for the oxygen sensors. They are literally two days old (all 4).

The only other anomaly I spotted is an orange connector by my overflow tank. Nothing is connected to it and I don't see anything that would plug into it. There is a gray connector that is plugged in on the same bracket.??

 

Before you take everything apart, do a smoke test. You can look up my "how to smoke test with a cigar" it's easy, quick and cheap. If all the misfires are on one side then you may want to check the valve cover gasket on that side, they can be difficult to get on just right.
If you have that many misfires then I doubt that you need new injectors because all of them failing or getting plugged on just one side is highly unlikely, just get new O-rings.


I checked for the orange plug you are talking about. Is it the one between the fuse box and coolant tank? If so, then yes it is plugged in on my truck. I couldn't tell you what it goes to though. It might be for SAI. Do you have SAI on your disco? I'll do some research and let you know what I find. UPDATE: hey I think I found a picture of the orange plug you are talking about. Check page 1423 of the RAVE and look at the diagram in the top right of the page.

 

Jared,

+1 on the orange plug. Something I didn't buy I guess... I was hoping it plugged into a passenger bank anti-misfire device.

Help me understand how the valve covers would affect the misfires so I know what to look for. I don't smell oil anywhere, but I can't see a leak in the back unless I remove the intake (which I will, tonight, probably).

I have the o rings for the injectors. When I remove the intake to replace the coil (tonight, most likely), I will replace the o-rings, though I have never done anything with injectors other than remove the wiring harness when I did the HG. Do they just pop out?

I checked my coolant level over a period of days. I used a sharpie to mark the cold level. I don't seem to be losing any, so I assume the HG job was a success, though I am now paranoid about the normal condensation drip at first start up. It is starting up without a hitch (whereas when the HG was leaking, it was difficult to start in the mornings and after sitting for long).

since I will have the valve cover off... i read somewhere about spinning the valves and springs until you hear metal to metal. Anything to that? When I put the heads on they were extremely clean, with no gunk at all on top or bottom of either head, and the rockers moved very easily. But I have to admit I don't know much about valves. I have run induction sea foam a couple of times, and I don't hear any ticking.

Finally, I have been reading about potential causes almost constantly. There is alot of advice out there, and alot of it is from people who have never worked on their own vehicles (the same folks who gasp at changing stock tire size or putting a sticker on your bumper). One of the things I read caused me to search my memory for the onset of the misfires. A person claimed that our systems were not designed for 4 prong spark plugs. I use Bosch +4 Platinums. But I have also used old school AC Delco spark plugs, and had the same misfires with both. Also, if that was a problem, I would think it would affect all cylinders (since my spark plugs are all the same, obviously). I have an old Mercedes and I think I read it on a Mercedes forum; I can't remember. But I have swapped my plugs three times in three months and don't plan to do it again unless someone in the know strongly advises it. Stalling here, my memory reports that I have had the +4's longer than I have had misfires.

 

Jared I wonder about that.. I just caught your statement about a fuel pressure test. I need to figure out how to do that because I DO smell gas occasionally. I have no idea how to do it but I will Google it.

I don't smell gas in the engine compartment, but I smell it outside. I have smelled it inside, too (not strong,. but I don't transport gas cans so I can't imagine why I would smell it inside, unless it is seeping in from the outside smell). Maybe I should let it idle awhile then see if I can locate the source of the smell. Are you thinking a fuel pressure problem or leak could affect the passenger bank of cylinders?

Wow, fuel pumps are expensive. http://www.roverparts.com/Parts/WFX101060K.cfm

 

I have noticed on this and other land rover forums that others have had this problem... so often that DiscoMike has replied "I've seen this problem before and none of the suggestions that have been made fixed it; I don't know what causes it", or words to that effect. I have yet to see a resolution. And after reading SO MANY threads on various topics that just taper off without a report of the resolution (even if it is: I just sold the damned thing to an idiot), I will certainly post the solution, even if it is "I rolled it back into the garage to think about it for a few years like last time".

Another common theme is head gaskets. Most of the threads indicate that the head gasket was replaced. My misfires appeared when I was having a HG problem. It continues after I replaced the HG. On the other threads it is not always clear whether the problem appeared before and simply continued (as mine has), or popped up after the HG job.

While I am reasonably confident in my HG job I did read that Advance Auto has some dye you put in the anti-freeze, then drive around, then check the plugs in suspect cylinders for dye. Sounds like pure genius and I didn't see it before. Can't be more than five bucks.

 

If the Valve cover gasket is leaking bad enough is can drip oil down on the plugs (very unlikely your problem unless you have a very bad leak).


To change the Fuel injector O-Rings just un bolt the fuel rail and pop off the clips that hold the injectors to the rail and pull them out. You can put a tiny bit of oil on each o-ring to help them go back in.


To do a fuel pressure test you need to hook up a pressure gauge to the Schrader Valve (it's on the back of the fuel rail and very hard to get to) then start the truck and look at the reading from the gauge. After you turn off the truck leave the gauge on for another hour and come back every 15mins and see if the PSI has dropped any.


I run +4 plugs in my truck with no problems, so they are not the issue. I am still thinking you will fix your problem with the new coil. I'll keep my fingers crossed for you.