Hi guys need some input please,i have a Vacuum leak on the rubber pipe that runs from the inlet to the top rear of the valve cover,how would this affect the running? and today another problem has appeared,when i start her up the engine revs up then dies down to tickover? i was sitting at the lights today and it did the same,was at tickover,then the revs jumped up and died down again? im getting frustrated,iv had new plugs filters etc its a 2000 xj classic 4.0 and my daily driver so need to get her running sweet,would appreciate your help guys.

 

fix tube its causing vacuum leak which causes high idle.

 

Ok im defo gonna sort that,but she ticks over ok once shes running just this weird thing on start up and as i said it did it at a stop light but not everytime?,but thanks for the answer il get on that fix...

 

Would i be correct in saying that the IAC could present these problems? is it straight forward to remove and clean,and is there anything obvious to look at when its off?

 

Ticks over and does a weird thing?

I'm assuming you have a rough idle and it can stall when it's supposed to be idling. These are symptoms of a dirty IAC, and sometimes a worn TPS. Search for writeups on here on how to clean the throttle body.

 

Hi Salad,well iv just fixed the vac pipe,the engine idles fine,but when i rev it,the revs shoot up but take ages to come back down!!!:

 

Possible sticking IAC

 

Thanks Freegdr,im gonna tackle that tomorrow and see if i can cure it...