04 Disco Cylinder 8 misfire
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7th Gear
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04 Disco Cylinder 8 misfire
Hi guys and girls,
I recently got my discovery back from the shop where they put new plugs and wires in and all lights were off the dash (miracle!).
I drove it for a couple of miles then the SES light came back on and got P0308 code again and could tell there was a misfire when going up hill and the rough idle.
After reading other related threads, it sounds like it could be head gasket or fuel injector replacement? I checked this morning and didn’t see any leaks on the ground either.
I’m going to call the shop again today but wanted to have somewhat of a diagnosis before taking it back. Any help would be greatly appreciated.
Thanks everyone!
I recently got my discovery back from the shop where they put new plugs and wires in and all lights were off the dash (miracle!).
I drove it for a couple of miles then the SES light came back on and got P0308 code again and could tell there was a misfire when going up hill and the rough idle.
After reading other related threads, it sounds like it could be head gasket or fuel injector replacement? I checked this morning and didn’t see any leaks on the ground either.
I’m going to call the shop again today but wanted to have somewhat of a diagnosis before taking it back. Any help would be greatly appreciated.
Thanks everyone!
If they just did the plugs and wires, the boot at the coil pack and the boot at the spark plug. All it takes is a small hairline crack to cause misfires. Pull the spark plug out. Also look inside cylinder when the plug is out. If it's perfectly clean in there, suspect head gaskets.
I know I’ve said it 1,000,000,000 times, but anytime you’re going to the trouble of new spark plugs & wires I highly recommend replacing the coil packs at the same time (especially if you are still on the OEM coils). Then you know without a shadow of a doubt all your hardware is new. Before jumping to HG’s you can double check the plug (some times they get dropped at the auto parts store), the wire, and you can examine the plug itself to see if it’s wet or getting discolored.
Camel Trophy
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From: Charlotte
When diagnosing a problem always first ask what's been done or what has changed that might explain the problem.
Since the misfire appeared within a couple of miles of having the plugs and wires changed that's the obvious starting point. It's very possible the shop did not get the cylinder 8 boot seated fully on either the coil pack or the spark plug, or, as others have said, it's possible the spark plug is defective.
Start there and eliminate those possibilities before even thinking about head gaskets or something else.
Since the misfire appeared within a couple of miles of having the plugs and wires changed that's the obvious starting point. It's very possible the shop did not get the cylinder 8 boot seated fully on either the coil pack or the spark plug, or, as others have said, it's possible the spark plug is defective.
Start there and eliminate those possibilities before even thinking about head gaskets or something else.
Last edited by mln01; Dec 19, 2018 at 07:38 PM.
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7th Gear
Joined: Jul 2017
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Thank you everyone for the responses, I’m learning a lot about this truck with the more problems I have 
I spoke to a rep at Atlantic British and he said the same thing, start by replacing the coil packs and go from there. They are new plugs and wires but not new coils packs, which makes sense now to have just replaced all of it. Not saying this may be the solution butlikeyou guys said, start small and go from there. Any recommendations on coil packs?
Also, to preface this I was getting cylinder 8 misfire prior to the shop which is what made me put new plugs and wires on in the first place.
@mln01 are you in NC?
I spoke to a rep at Atlantic British and he said the same thing, start by replacing the coil packs and go from there. They are new plugs and wires but not new coils packs, which makes sense now to have just replaced all of it. Not saying this may be the solution butlikeyou guys said, start small and go from there. Any recommendations on coil packs?Also, to preface this I was getting cylinder 8 misfire prior to the shop which is what made me put new plugs and wires on in the first place.
@mln01 are you in NC?
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