Hi, I drove my car during Friday evening rush hour traffic, some stop-start leading up to a roundabout. When coming off the clutch to move forward the car was stumbling. I then went to pull out at the busy roundabout and the car misfired and then took off as normal. I checked my oil the next day (just routinely checking the oil), the level was fine and it didn't seem less viscous than normal, but there was a strong fuel smell.

I then drove it again about a week later to a tyre fitting appointment I had booked before the misfiring started. I was deliberately trying not to rev beyond about 2.5k in case the oil was badly diluted, all in I probably did about 24 miles that day on half national speed limit roads and half urban. I didn't notice the car misfire once and when I checked the oil the next day it did not smell anywhere near as strongly of fuel (still a slight smell to it), I assume the oil warmed up enough to vapourise whatever fuel was in there, and no more was added as it didn't misfire, which leads me to believe the oil dilution is due to the misfire.

I don't know if it didn't misfire on this second journey because of me trying not to rev it too much, or if it is just an intermittent issue. It does seem to have a slightly off idle, it goes up and down very slightly but seemingly only when cold. It does also have quite a rich fuel smell from the exhaust when cold starting. I did notice when starting there's a ticking noise from the engine bay, almost like the water pump is knackered (it was changed not long ago). It goes away as soon as I start moving, and if I stop again immediately and listen for it it's not there anymore.

I have had a misfire with this car before, I had the spark plugs changed twice, each time it seemed to fix it for about a month then it would return. I eventually had the coil and leads replaced and this solved the issue for about 18 months. I have heard the aftermarket ignition leads for these engines are crap, so could that be the problem? I don't drive many miles so could old fuel be the problem? (E10 is meant to go off fairly quickly)

The car has had an intermittent battery light for basically the whole 5 years I've owned it, it normally comes on 3-4 times a year, and if I pull over and restart the car it goes out and does not return. I don't know if this is related. I have also noticed a slight induction whine, I can't remember if that's always been there or not. After a long journey I noticed the boot floor was hot above the exhaust back box, again unsure if this is related.

I know the worst case is a piston ring, but as the engine has only covered 82k miles, and I have had it serviced every year, I think it's very unlikely (also doesn't perform any worse than before so I think it would be noticeable if it was low on compression). Are there any common causes of this behaviour with these cars?

Sorry for the long post, thanks in advance for any advice

So which cylinder misfires ?

What is the DTC ?

I don't have a scanner so I'm not sure. It's going to my local mechanic tomorrow so I assume they'll have a decent one, just looking for any common problems that could be causing this

21 hours ago, unofix said:

So which cylinder misfires ?

What is the DTC ?

Went in to my local garage earlier, they had it idling and drove it about for half an hour total, couldn't get it to misfire, checked for water around where the leads meet the plugs and there wasn't any, seems to be a very intermittent thing. They couldn't find anything wrong with it, I'll have to keep an eye on it

My best guess is a slightly dodgy earth somewhere? Would perhaps explain why I have a very occasional battery light that goes off when I restart the car