Took my coupe for its MOT last Wednesday. Drove in fine and dropped it off. Tester called at lunchtime saying the car was misfiring and shaking a lot. It was fine when I drove in so didn’t know what to make of this guy. Anyway, he was dead right. When I picked the car up it was shaking like a washing machine. It failed the MOT because they couldn’t do the emissions due to the misfiring and there was play in the Nearside Front Lower suspension arm ball joint. Not to fussed about the joint because I can easily replace that. The misfire on the other hand is far more worrying.
The garage i had taken it to was only a tyres and exhaust kind of place so they won't touch the engine. I drove it home gently and the EML came on which I was glad of as it give direction to the fault.
Got home, scanner out, cylinder 6 misfire code. I pulled all of the spark plugs and the cylinder 6 plug was closed which explains the misfire. Photo below.
Is it normal for old plugs to close? I assume that as plugs wear, the gap increases causing a misfire. Can the undetonated fuel collect in the cyclinder and eventually cause a mega bang and weld the plug together? The contraction of the weld causing the parts of the plug to pull together.
I'm wondering whether old plugs could make too much of a bang and weld themselves together? Or is this more likely to be something mechanical and contacting the plug? Loose piston. Broken piston ring. Worn out crank shaft bearing?
I gapped the plug and put it back in, switching it with the one in cylinder 5. Seems to run fine again. I've not had a chance to pull the plugs again before we went on holiday. Was going to see whether the plug now in cylinder 6 also got ‘squashed’. I'll replace all of the plugs very soon but need to diagnose the fault first.
Has anyone else had this? Any advise will be much appreciated.
The garage i had taken it to was only a tyres and exhaust kind of place so they won't touch the engine. I drove it home gently and the EML came on which I was glad of as it give direction to the fault.
Got home, scanner out, cylinder 6 misfire code. I pulled all of the spark plugs and the cylinder 6 plug was closed which explains the misfire. Photo below.
Is it normal for old plugs to close? I assume that as plugs wear, the gap increases causing a misfire. Can the undetonated fuel collect in the cyclinder and eventually cause a mega bang and weld the plug together? The contraction of the weld causing the parts of the plug to pull together.
I'm wondering whether old plugs could make too much of a bang and weld themselves together? Or is this more likely to be something mechanical and contacting the plug? Loose piston. Broken piston ring. Worn out crank shaft bearing?
I gapped the plug and put it back in, switching it with the one in cylinder 5. Seems to run fine again. I've not had a chance to pull the plugs again before we went on holiday. Was going to see whether the plug now in cylinder 6 also got ‘squashed’. I'll replace all of the plugs very soon but need to diagnose the fault first.
Has anyone else had this? Any advise will be much appreciated.
