Misfire?

[Seymour197]

Hi I need a little help. My car has now started to what I think is misfiring quite badly. It doesn't do it when I first start the engine. After a few minutes it starts to hesitate badly and sounds like a Subaru Impreza. The cat also smells quite badly. Turn the engine off for a couple minutes, third it back on and still doing it. Drive it down the road then it clears and seems to be fine for the rest of the journey. I took it to Renault who diagnosed a faulty lambda probe. I've had that fitted and it's still doing it.

Anyone have any suggestions. I have read a lot about the coil packs going down but why would the cat smell?

Please help

 

[Fernandez]

Not sure about the cat but check the coil packs first. Sometimes the connectors into the pencil coil can work loose so check those first

 

[Gez]

I'd have said lambda sensor at a guess, don't the Clio's have 2? Which one did you change?

 

[Foxspeed]

could easily be a plug...

have got a obd2 reader - could be a stored ecm code?

most likely electrical side ie spark plug/coil pack - easy enough to sort if you know what your doing...

 

[Seymour197]

I thought lambda sensor due to the smell from the cat when it was running rough then not when running fine. I've changed the downstream lambda. It also hasn't got any engine warning lights flashing either. Would the fault have to be erased for it to recognise a new lambda probe?

 

[Pav]

check it at 9:30 ......
http://www.youtube.com/watch?v=iuxDWKo_ngc

 

[Merde Francais]

It sounds like a misfire on one cylinder, the smell will be the unburnt fuel in the cat. Firstly you need to identify which cylinder is misfiring then go from there. As stated above it's likely to be a coil or a plug. When did it last have a new set of plugs? If it was a while ago I'd start by changing those as it won't cost a fortune and should be replaced over time anyway.

 

[Seymour197]

The plugs were changed about 3 months ago

 

[Glenn_Adam_Doble]

mine does it on high idle, sometimes, best way to get past it is, be very light on the throttle when setting off, and leave it in second and increase your speed slowly until you feel it free up,

I think its since I put the exhaust on, think its related to the flat spot, even after ive had it mapped it still does it, but mine does it here and there, has done for months and months,

what mods have you got ?

 

[Seymour197]

Good news ive changed the coils and it seems to have sorted it.thanks for the advise everyone

 

[Foxspeed]

I thought lambda sensor due to the smell from the cat when it was running rough then not when running fine. I've changed the downstream lambda. It also hasn't got any engine warning lights flashing either. Would the fault have to be erased for it to recognise a new lambda probe?

the downstream o2 is more for making sure the main cat/o2 sensor are working correctly and for odb2 diagnostics - the first o2 sensor has more influence on fuelling...