Is it the 5th injector?

hi all, I'm a daily driver.
I start my 1600 gti off the button. Sometimes she sits at 1200-1250 rpm while cold, then nicely to 850-900rpm when at normal temp.   :mrgreen:
But annoyingly sometimes she starts and goes way up up to 1700-1800 rpm before going down to the normal 900 ish.  
Any help plse?!?!
Jjl.

You could disconnect it, electrical plug only. you won't damage anything. then see if the problem reoccurs. High revs could also be caused buy an air leak opening ocasionally.

Rob  

i have this problem at the moment and its 2 of my injectors are slightly loose so every now and again they get loose and the revs go up to 1500-1600 at warm up.
when it happens try moving them slightly and see if yours revs change

Steve

The auxiliary air valve is the bit which gives a higher idle during warm up from cold. It should only be increasing the idle by +400rpm or so, so it could be faulty. You can disconnect it to test it too.

An air (vacuum) leak would also raise the idle speed, but it would be there hot or cold.