Intermittent lumpy engine

[cooperR]

Hi all. I just noticed that my Mk2 Gti has developed a mild sickness. After short blasts driving around with occasional high revs, the engine would settle into a lumpy idle at around 1k rpm, as if the fuel mixture changed. This ceases to occur once the engine is restarted and would immediately feel smooth. Subsequently, it will revert to the lumpy mode once driven for a short while at high revs. Any advise would be greatly appreciated as I could not pin point the problem area and it is driving me nuts (the engine sounds rather good at lumpy idle thou, a bit like an air cooled VW  ) . Thanks.

[DarnPB]

What injection system are you running? Kjet or Digifant?
It may just be a case of worn plugs. Worn plugs could overheat and cause a hotspot in the cylinder. This will in effect alter your timing by causing the mixture to burn prematurely.

[Conker]

My 16v does similar things when it needs new rotor arm/cap/plugs.

[maxp]

MMm mine is similar - ok when first starts - constant 'brrr', but after 30 mins the 'brrr' is replaced intermittently by the odd cough.

It used to do it really badly but ive chnged the leads and plugs but it still does it a bit...rotor arm need replacing?

Mine is a digi btw

[OakeyDoak16v]

MMm mine is similar - ok when first starts - constant 'brrr', but after 30 mins the 'brrr' is replaced intermittently by the odd cough.

It used to do it really badly but ive chnged the leads and plugs but it still does it a bit...rotor arm need replacing?

Mine is a digi btw

Just change it, only costs pennies

[cooperR]

Thanks,you guys are ace  Will have those replaced then.Mine is a k-jet 16v kr with 9a block.

[mattkh]

....... This ceases to occur once the engine is restarted...

Hi
Is the restart done immediately or after a few minutes ?

[cooperR]

Hi Matt, the restart is done immediately,every time.The engine seems to reawaken to silky smooth idle by doing so.