Misfire

[Josho.]

Clio 1.4 16v has a big misfire. It's definitely an ignition issue as unburnt fuel is igniting in the exhaust.

It was clearly running on 3 cylinders and I stopped, exhaust red hot and pulled the coils out. Number 3 made no difference whatsoever so that's the issue I thought.

On the way home I noticed the rev gauge fluctuating everwhere and then the central locking locked. Perhaps a ground fault somewhere as the central locking normally locks after 10mph or so.

The misfire though I started it once it had cooled a bit and pulled cyl 3. This time it made a small difference. Number 2 makes a small difference and 1 or 4 both cause a big difference and it cuts out.

Switched 3 and 4 coils still does the same. Went for a drive bit better but as soon as they warm up it misfires again.

Worth risking buying a coil? No fault codes whatsoever.

 

[ben lee]

sounds like the coils are braking down underload and when hot. very common on the 1.4/1.6 16vs.
the new ones renault sale are a modified version.

 

[Josho.]

Finally got a P0303 error. Measured resistance of coils and injectors all normal. Swapped injector 3 and 4 around and coil 3 and 1 misfire a bit better running for some reason. Still misfiring though. Sometimes last night was definitely going onto 3 cylinders. Bought a new coil and replaced the suspected faulty coil. The fault will not come back though and my computer won't detect any misfires. Was hoping there's a common fault or something. All cylinders cause extra issues if disconnected on idle. Cylinder 3 plug was dirty dry and black after one journey.

I'm wondering if it is an injector issue, something is breaking down under load, also causing rev counter issues. I'm just about to replace TDC sensor as it's causing idle issues.

I will just bit the bullet and buy three more coils I think. Just hoping it isn't then injectors!

 

[ben lee]

be worth putting a set of good quality spark plugs in too.

 

[Josho.]

Sorted, was coil number 2, assuming as usual number 1 is furthest from gearbox on these engines?

Code threw me off the scent big time. Just swapped about.

Still a low idle so will be cleaning throttle body and ICV. NGK plugs recommended? Tempted to change all the coils but if it ain't broke!