Evening all.

As the title says…..

I developed a misfire under heavy acceleration tonight and car threw a ‘reduced engine performance’ message along with the EML for around 5 seconds then disappears.

Car is running perfectly normal otherwise and feels like it’s running on all cylinders until it gets to 4-4.5k rpm.
Then it splutters and gives a rattling noise in the engine until throttle is backed off.

My generic code reader shows P0302 & P0304 misfire detected on cylinders 2&4.

I was actually warming the car up at the time to diagnose an intermittent EML for what I suspect to be a bad 02 sensor as I am getting weird voltage figures from them. Not sure if this could be connected however the 02 sensor problem is ongoing and has never caused a misfire before.
Attached is a snapshot of the o2 sensor voltages in case it is relevant.
Thanks.

Click image to enlarge

I’d start with the easiest thing first, swap the coils from cylinders 2 and 4 with another 2 cylinders and see if the misfire follows the coils.

If it does you’ve got your fault, if it doesn’t it could be plugs.

How many miles has your car done as it could be worth doing all of the plugs anyway if they’ve not yet been done.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

Car has done almost 150k miles…..

Is swapping the coils an easy enough task? 2005 (55) Range Rover 4.2 Supercharged Vogue SE Java Black

Yea, it’s not too bad.

There’s a plastic cover over the top of them that you can pull off and then there’s one bolt holding the coil in. Remove the plug and the bolt and give them a good tug and they’ll come off.

If it hasn’t had the plugs done at 150k it’s probably worth doing them too.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

Just watching a video on it just now like you say looks pretty easy so thank you…..

Can someone tell me what side of the engine is bank 1 & 2 if I am standing at the front of the car facing the engine please? 2005 (55) Range Rover 4.2 Supercharged Vogue SE Java Black

Cylinder 1 is the front offside, 2 is the front nearside.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

Thank you 2005 (55) Range Rover 4.2 Supercharged Vogue SE Java Black

Check your fuel pressure as well

Check the little boost pipe between sc and fuel pressure sensor Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Still trying to find out the reason for this misfire and have came across this plug and can’t see where it would go.
Anybody have any ideas?

Click image to enlarge

Click image to enlarge

Is it the plug from the fuel pressure sensor? Whip the engine cover off four but it’s on the right if you’d rant on front of it with a boost pipe going to it Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Hi,
Had the cover off there but couldn’t see anything that didn’t have a plug in, everything seemed to have a plug in it as it should.
Could It be a spare or is it definitely meant to go somewhere in folks opinion?

Thanks. 2005 (55) Range Rover 4.2 Supercharged Vogue SE Java Black

Mine is in bits at the moment so I’ll have a look tomorrow and see if I can find your plug. It doesn’t look familiar though I’m afraid.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

Thanks very much,

Had the airbox and intercooler plastic intake off today again but can’t see any connectors etc missing a plug. All plugs and connectors I could see were full. I’m starting to think it’s always been loose and I’ve just never noticed. 🤷🏻‍♂️ 2005 (55) Range Rover 4.2 Supercharged Vogue SE Java Black

Just to be sure, that’s a grey 2 pin plug? What colour are the wires going into it? If you follow the wires back, where do they leave the main loom? 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior