Miss fire on disco 2

Hi
My latest disco 2 has a miss fire which I am hoping someone here can give me a few pointers. The compressions are all ok, water good and no issues with contamination etc. I believe the problem is ignition or possibly injection. The leads aren't nice and I will swop them and the plugs in a day or two. Do the coil packs case a miss fire which is worse when the engine is first started but then slowly improves? The miss never goes and the engine is down on power. Just looking for some idea where to start playing.

Your quite rightin believing that the problem is ignition or fuel system related, it usually is.
Change leads and plungs, if the misfire is still there we will move in deeper including iffy sensors or coils, and engine management being plugged into a diagnostic kit, also then u can provide more information on when exactly the issue accurs.




Sent from my iPad Air on a train.

Look for sparks jumping in the dark

I have new leads on order and new plugs to stick in with them. I also have another car which has more major engine problems but no misfire so I can borrow bits as needed to double check Once I change the leads, I will go for the plug in to get a few error codes to get me started.
My plan is to get this one working well and then probably use the good bits from my other one to make this one into a keeper. Will know more soon enough

Don't forget will you, to keep the forum advised on the progress

So the HT leads were horrible, all rusty and falling apart. I also gave it a set of plug and it is driving a little better but miss fire still there. Power a bit up and misses a bit less once hot.
No error codes on system and a small exhaust blow but hardly noticeable so I doubt it's the whole issue.
I am thinking of swopping coil packs next unless someone has some good ideas of things worth playing with first.

As the coil packs are wasted spark, wouldn't the opposite plug be miss-firing too? The coil packs are a real pain to get at and change so I'd look elsewhere first. My D2 had a similar problem with a small exhaust blow, however I got a bit of hose to the ear and started poking around with the other end to see where it was coming from and it turned out to be a head gasket. That led to a whole host of other things (which I sure you don't want to know about)

We have had issues with the 3-way connectors on the sides of each coil pack.
Check for corrosion on the terminals and the flying socket.
Our Son's failed in Carpentras, south of France but we had spares at home which we had sent out by courier.
Peter

Thanks, those are all useful ideas. I do have a miss fire on more than one it seems and they do appear to be linked to the same coil pack so I am hopeing that my answer lies there. Unfortunately I have had it suggested today that another possible cause for a more noticeable miss fire when cold and generally down on power is a worn cam. Never occurred to me but it makes sense as my compressions are actually a little better than they probably should be. I am going swop coil packs and also sort a small exhaust issue out first as these are not particular time consuming, checking connections too from the sounds of it as I go.

If the problem is still there, then i guess it will be time to have a look inside the rocker boxes to see how much movement is occurring there.

I think that worn camshafts went out with the 3.5's.

Peter

Beg to differ - my last V8 rebuild was on a Disco 2 and the back lobs were almost flat. I read somewhere it was due to the wider ribbing shielding the oil from splashing up????

Broken my foot by trying to be a hero and stop some children (24 year olds) from killing each other. One of them must have stood on me in the process so I now wont be playing engine for a few weeks!

I think that I will hope the issue did go with the 3.5 as its easier to deal with. I do unfortunately actually think that my problem is most likely down to the cam, the person who suggested that option is very rarely wrong unfortunately. I will get to check it out soon enough. At least its not too bad a job to do and when done, the engine should be very happy again.

So, 8 months later I eventually got feed up with driving around on 6 so I decided it was time to find out more about my miss fire. I stripped the top manifold off and rocker boxes and checked the cam lift, it was all fine after all so I then tested the coil packs properly and found one was ............... I can't really remember why I didn't test this properly in the first place, too many other things to do and the car seemed happy to be a v6 for a few months when I did use it.

Anyway, now its got 8 and also a new MOT to go with it!