Clio 172 ph2 poor running/misfire

[Anthony Johnson]

Hi all,
I've lurked on this forum for a long while, but yet to post. Need a bit of help with an issue.
Noticed the car is grumbling and runs rough, investigated the issue a bit.
Taken to garage but no fault codes found (besides aircon), so they gave me it back without charge.

I've changed the spark plugs, these haven't been done since at least 2015 so probably overdue.
Noticed plug 4 (LHS) was sooted up. After changing this continues onto the new plug.

I'm guessing this might be an injector, but before I pull the trigger on this am I thinking along the right lines?
I ask because on looking on this board and others, these tend to throw warning lights and/or fault codes.

Beyond that all I can think of is HT leads, or god forbid compression. Have ruled out coil as the other cylinders are fine.

Thanks!

 

[hopgop1]

From what I've seen injectors will often start failing long before you get a code. If you've not got a record of them being done in the last few years, it's the first thing I'd try. Just make sure you put genuine magneti marelli in, they're quite fussy apparently.

 

[Colin-S]

This might be helpful

 

[Anthony Johnson]

From what I've seen injectors will often start failing long before you get a code. If you've not got a record of them being done in the last few years, it's the first thing I'd try. Just make sure you put genuine magneti marelli in, they're quite fussy apparently.

Thanks. Will change the injector on the offending cylinder tomorrow, and probably the other three after

 

[hopgop1]

Thanks. Will change the injector on the offending cylinder tomorrow, and probably the other three after

100% do all 4, not a big expense, and if ones going, they all will be sooner or later.

 

[Anthony Johnson]

So changed the offending injector, which was measuring 7ohms.
Engine runs better, but still imperfect.
I randomly checked for blowback from the filler cap. A decent amount, so I'm guessing piston ring/s = terminal. Done 130k miles.

 

[chazza114]

So changed the offending injector, which was measuring 7ohms.
Engine runs better, but still imperfect.
I randomly checked for blowback from the filler cap. A decent amount, so I'm guessing piston ring/s = terminal. Done 130k miles.

It wouldn't hurt to do a compression test just to confirm your suspicions.