Misfire Help

[richd]

My cars a ph2 172

Parked my car up the other day, been absolutely fine. then started it up the other morning and was misfiring like hell.

So ive replaced the coil pack as that was cracked so i asumed it was that but its still miss firing, i took out the plugs cleaned them up and then the car was fine, no misfire. 2 minutes later it was back i noticed that the plug on cylinder 3 got very sooty, very quick, but im not sure if it did this while running, or when running with the misfire. did the same again, cleaned, and then it run fine, then started again, and cylinder 3 plug was sooty again.

There is no smoke coming out the back at all. and when it wasent misfiring, after a cleaning the plug it ran great.

im thinking of replacing the plugs again, but there only about 4 month old ( there the correct platinum ones by the way) and also the ignition leads, but i dont want to buy them and it be somthing totaly unrelated that im missing.

Thanks

 

[dano17439]

Could be a dodgy injector, but I would get a diagnostic done to save you guessing the fault and save you spending anymore money where not needed

 

[MicKPM]

From what you've said I suspect a lead fault - Its not a scientific explanation nor is it a promise that it will 100% be the leads but the fact you seemed to have cured it for it to return again later says its not likely to be an injector fault.

 

[richd]

my thinking was that moving around the leads and it then working, but coming back, was a lead fault. Cheers guy, think i might just replace plugs and leads, last stop will be an injector if that dont work lol.

 

[MicKPM]

Aftermarket leads (specifically Magnecores) by any chance?

 

[richd]

nah they were just standard Renault ones lol

 

[Sam_K]

I had this recently. Car was intermittenty misfiring and EML flashing. Did exactly what you did changed coil pack, cleaned plugs. Turned out to be an injector.

I pulled each connection of the injector whilst it was running and could notice a very faint change in engine note when the faulty one was pulled off.

 

[richd]

Yup just fixed it today, replaced the coil pack, leads and plugs, was still misfireing, turned out it was the injector too. next day replacement from renparts, fitted today. all sorted now