I just bought a 2001 land rover discovery and took it to get safety and emissions done. It failed safety bc Cylinder 1 and 6 were misfiring. Has anyone else had this problem or have any recommendations on what will fix it?

 

There is nothing magic about the 1 and 6 combination. Misfires can be caused by alot of things and not knowing your level of mechanical knowledge, and therefore meaning no insult, they can be classed air, fire, and fuel. And compression.

For air, check for vacuum leaks. You can sometimes hear a hiss over the sound of the engine that will point you in he right direction. If not, you can spray brake cleaner or wd40 on the hoses that enter the intake on the top of the engine. If the engine changes when you do that, the fix could be as simple as some duct tape.

For fire, you can swap the spark plugs from good cylinders to bad ones. If the misfire moves, it is the plugs. If not, it could be the spark plug wires and you might check to see if they are touching or crossing anywhere.

For fuel with just two misfires you could have problems with the injectors, but swapping them is a bigger deal (they are under the upper intake). You could also have a vacuum leak at the injector o rings or the upper intake plenum gasket. Or maybe the injector harness ground wires are disconnected.

Misfires can be caused by blown head gaskets. If you remove the spark plugs from 1 and 6 and point a flashlight in the spark plug holes and everything is really cleaned... Like steam cleaned... That could be the cause. But that's a huge leap and you would see low coolant if that was the case.

If your rings are worn or broken low compression or a lack of oil could also cause misfires. But there's no reason to assume that.

It would probably be helpful to know if you had other codes. Do you have a code reader?

 

DII Firing Order

1 and 6 are on the same coil, mine got new coils from advance auto and eliminated the misfires.

 

definitely check that coil

 

Nice catch!

I thought if the coil was bad it would cause misfires on all 4 to that coil. Not so?

 

Thank you! No insult taken. I bought new spark plugs, spark plug wires, coils, upper inlet manifold. I changed them all this weekend. I did break the brake servo vacuum pipe connection :/. I will check the other things you said later today. My neighbor is supposed to get me a code reader from his work. If not I can go to Autozone or my friends body shop.
There were a few other codes that failed. I know one was the KOER. The rest I will have to check later.

 

That brake servo connection is a piece of poo. Holding the ring in while pulling the plastic pipe is counterintuitive. The end of the plastic pipe will chip off and go in your engine when it gets brittle. And even when you have a new fitting it doesn't look like a good vacuum seal. Finally, those plastic rubes get brittle with age and will crack just to spite you. I am talking about the one with the plastic ring (yellow or red) on the front/passenger of the upper intake. If you have a friend with a shop, the best course is to go to Lowes and get a brass ****** fitting from the plumbing section for about 5 bucks, thread that hole, and use vacuum hose on the ****** end. It will look professional and make your future bright. It will be less than half the cost of a new fitting. You can put duct tape around it until you do that fix but the tape always comes loose. I wouldn't use silicon or anything that could be sucked in because there is a lot of suction at that port and it will end up in a cylinder. To remove the fitting you hold the intake butterfly open and use a long poker (I used a long socket extension) to punch it out from the inside. It is very satisfying to throw that fitting in the trash.

Sorry for my bad advice on the 1 6 combination. I was too lazy to look at the coil diagram and I thought all four would be misfiring if the coil was bad. I'm still learning.

The forum thinks barb ed is a cuss word. I dunno why. I don't say that when I hit my finger or my dog won't stop barking. Anyway. Barb fitting. The one right behind that fitting is also a good candidate for a Barb fitting and it is already threaded. Mine is brass now. .. I can't recall the size and thread pitch but I think there is a thread here somewhere or you can just twist out the black plastic one and take it to the store with you. Both will cost less than the replacement fitting for the front one and you'll have an excellent seal.

 

I went to Lowes and bought a brass ****** fitting and a Tap & Die set. I tried drilling a hole to match up so I could thread it. I finally realized that there was a plastic fitting in there. ugh!! Lowes and Home depot didn't have a big enough Tap & Die set so I went to Harbor Freight. I got a 1/2 inch one. Tonight I will be able to try again.
I did notice that there was an electric plug that I can't find what it attaches to. Ill get a picture if I cant figure it out and see if you know.
Thank you so much for your help!!

 

There are four electrical plugs in the upper intake area. One going to the temp sensor in the top middle. It is round. The rest are on the driver side of the intake. Two of them go to cylindrical doohickeys. The gray one goes highest silver doohickey and the black one goes to the lower black doohickey. There is another plug that is black with orange and that is probably the one you are talking about because its location is a little hidden. It shoves up under the throttle position sensor. Top, driver side, facing the driver seat, just past where your intake hose meets the upper intake. There are hoses that block it from view. The plug goes in by pointing it upward with the plastic clip facing back.

 

Yay! That worked. The only one left is KOER fail. Do you know what that one is?