very strange misfire.... HELP

[cpcrampton]

Hello

Well i have a clio 172 cup. i get a slight misfire below 2000rpm. BUT.... this only happens after i have been for a run in the car. ie i can start it up from cold , the car is rough when cold and pops and bangs on over run but no misfire. it will heat up to the running temp and no misfire. if i turn the car off for 5min to 1 hour and return to the car i have a misfire below 2000rpm.

Note,: no warning lights on dash board at any time.

when the temp outside was very cold i was not getting this problem but now the temp is increasing outside its started again.

any ideas ? anyone had this before?

im thinking upstream lambda? but i do not know.
any help appreciated.

Chris.

 

[JackJack]

Your mpg would be affected if it was the upstream lambda mate.

 

[cpcrampton]

UPDATE: blue flashes coming from top left of coil pack when misfire occurs. could anything cause this to arc? or is it just a dodgy coil pack or ht lead?

 

[Dblock]

UPDATE: blue flashes coming from top left of coil pack when misfire occurs. could anything cause this to arc? or is it just a dodgy coil pack or ht lead?

LOL! Change leads and coilpack straight away if I was you.

 

[Ms_Technical]

A slight misfire after warming up will mean a lead is arcing. And then a blue spark, well thats the clincher lol. So Id say same as above

 

[.Kev.]

Sounds like HT leads mate.

 

[Joe R26]

HT leads for sure. I had the same problem on mine. cold starts were fine. Then it would start missing when it got warm. Only took a few days before it came undrivable.

 

[BoomOne]

yep sounds like leads, replace them first and then the coilpack if need be

 

[cpcrampton]

Thank you for the help gents.

 

[Dblock]

Thank you for the help gents.

If your anywhere near Dundee I can give you a shot of my coilpack and ht leads?