Misfire cylinder 8

[tvanstee]

Hi all, I have a 2011 LR4 that has a persistent cylinder 8 misfire. It will pop a code p0316 and p0308, does not give me a P0300. However with live reading I can see that it is constantly misfiring.

I've changed the injectors around, put in new spark plugs and swapped around coils. Misfire stays at cylinder 8. Have done compression test and everything checks out normal, followed up with leak down and it holds compression well. I love this rover but it is wearing on me.

Restricted performance seems to come and go. Some days it's there some days it's not. Even comes and goes while driving.

Any advice?

 

[Rover Range]

You need to see if there is spark coming from the #8 coil.
I've seen camshaft buckets break, causing the valve not to open fully.

 

[tvanstee]

Spark seems good, tested with an online spark tester and it seems to fire as expected.

I've never heard of cam buckets doing that, first time for everything I guess.

 

[jlglr4]

Fuel injector?

 

[jlglr4]

Nevermind…I see that you mentioned switching them around. I guess valves are the only thing left.

 

[Rover Range]

I've never heard of cam buckets doing that, first time for everything I guess.

It happens.
The valve stem will protrude through the cam bucket.

 

[tvanstee]

Looked into it today, but seemed to be a dead end.

Is there a possibility that the intake manifold has a crack that only affects one cylinder? Grasping at straws a little here.

 

[ebp02]

Had you messed with the engine bay recently? I had a similar issue on my scv6, left a loose ground on the miss fire head, lil 8mm ground by the cam sensors on the front of the head. Ultimately fried my ecu so I had it cloned. If your missfire comes and goes then maybe loose or broken cable/ ground for the coil pack. Check the wiring with a multimeter to the ECU and to the ground and go from there.

 

[LR4Slavo]

I would start with a compression test on the cylinder at this point, might also be beneficial to boroscope the cylinder to see if there's any obvious damage

 

[tvanstee]

Misfire seems constant, almost seems to be every other rotation. Cabling and grounding look good. Will have to check compression again