engine on idle

[The Gas Man]

i have a problem with my 1.8 , when the engine is on idle the revs go from about 500 to 750 constanly up and down , the lights and interior dash display also go brighter and dimmer, any thoughts

[chris1804]

idle valve?

[The Gas Man]

thanks mate, so what is an idle valve and can i do it my self, does it need cleaning or is a replacement part needed,

[ed taylor]

Air control Valve. Do you have one on the side of the throttle body. It might need cleaning or even replacing. I am not too familier with the 1.8 vec C. But if it is like the 1.8 vec B. Then if there are some small holes on the inside of the throttle body you could try spraying some carb cleaner onto them. I used to have to do this on the wifes Vec B. It worked for a while. But in the end. I had to replace the air control valve, as a spring inside becomes weak and will not work proporly.

[The Gas Man]

thanks ed, i will have to have a look in the morning mate, not sure were the throttle body is will have to check the haynes manual

[ed taylor]

thanks ed, i will have to have a look in the morning mate, not sure were the throttle body is will have to check the haynes manual

The throttle body is the "thing" that the air intake pipe from the air filter box is conected to. It is basicly the inlet manifold. Try doing a search for " air control valve".

[The Gas Man]

cheers ed still not had a chance to look though

[The Gas Man]

got some carb cleaner gonna give it a go tomorow

[carl bear]

if that doesnt work , could be the EGR valve (if you have one, some 1.8's do, some dont).

Mine was runnin slightly rough at idle turned out to be the egr valve.

[barkzz]

if that doesnt work , could be the EGR valve (if you have one, some 1.8's do, some dont).

Mine was runnin slightly rough at idle turned out to be the egr valve.

1.8 with an EGR???

Really? On a petrol? I've never heard of them having one, but i could be wrong, if so i stand corrected