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Seems like my new to me disco is giving me quite the welcome. After a coolant leak and a faulty xyz, now this. 83k miles. Yesterday it started to run rough from a cold start. Eventually gave me a flashing check engine light and then solid. First came up with p0300 and p0305 for cylinder 5 misfire and random misfire. Changed the plugs this morning to Bosch double iridium and ran good for about 2 minutes and then went back to missing. Same codes popped back up. Thinking of replacing the coils and going from there, but wanted to get some suggestions on anything else. I’ve read other threads on this and each leads to something different. Attached are a picture of old plugs.
Seems like my new to me disco is giving me quite the welcome. After a coolant leak and a faulty xyz, now this. 83k miles. Yesterday it started to run rough from a cold start. Eventually gave me a flashing check engine light and then solid. First came up with p0300 and p0305 for cylinder 5 misfire and random misfire. Changed the plugs this morning to Bosch double iridium and ran good for about 2 minutes and then went back to missing. Same codes popped back up. Thinking of replacing the coils and going from there, but wanted to get some suggestions on anything else. I’ve read other threads on this and each leads to something different. Attached are a picture of old plugs.
Plug wires are also important to maintain, and are more likely to cause problems than coils, which tend to be fairly durable. I would also check your fuel pressure and clean your intake and IACV.
Last edited by Jason Feuerstein; Dec 17, 2019 at 03:05 PM.
Plug wires are also important to maintain, and are more likely to cause problems than coils, which tend to be fairly durable. I would also check your fuel pressure and clean your intake and IACV.
it looks like it already has STI wires, which I believe are an upgrade (correct me if I’m wrong). I can try replacing them but I figured they would be fine because they aren’t original 2004. Cleaning IACV now.
STI wires are great. I had a set on my truck for 10½ years and 95,000 miles. I replaced them as a preventive measure a couple years ago because Rock Auto had them for $11.
I know it would be a pain, but you can confirm whether or not the wire is the problem by swapping the wires for 5 and 6 and see if the misfire moves to Bank 2. If it does I can send you my old #5 wire.
STI wires are great. I had a set on my truck for ten years and 95,000 miles. I replaced them as a preventive measure a couple years ago because Rock Auto had them for $11.
I know it would be a pain, but you can confirm whether or not the wire is the problem by swapping the wires for 5 and 6 and see if the misfires moves to Bank 2. If it does I can send you my old #5 wire.
If I swap them I’m assuming I would know the misfire is happening in 6 because the code would change right? Also not sure it’s just 5, because I’m also getting the random misfire code.
I just looked at the piston 5 head with an inspection camera and no sign of being steam cleaned, so head gasket is out of the question, for now... (hopefully). I think I’m just going to order wires and the coil packs and replace them. Hopefully that solves the issue. Not sure what else it could be.
Disco II misfire, codeS p0300 and p0305
