Technical fiat brava 1.2 80 sx over revving

[midnightrider]

hi,i recentlly purchased a fiat brava 1.2 80 sx,car was running fine untill the battery went flat,(car would still start) but since then when i start it the revs shoot straight upto 3000-4000 revs and stay there
does anybody have any idea what the problem could be,as i said was idleing at around 800rpm battery went flat and idles at between 3000-4000 revs ive not done anything or changed anythink so im a bit confused,have a brava manual but thats useless
thanks

 

[Adrian Bravo]

First thing to check is the inlet manifold back to the throttle body for air leaks. If air is sneeking in after the throttle body, it will rev higher because it is getting more air than it should.

 

[bridges]

First thing to check is the inlet manifold back to the throttle body for air leaks. If air is sneeking in after the throttle body, it will rev higher because it is getting more air than it should.

as above,

Also check that the throttle is not stuck open. Go under bonnet and manually move accelerator linkage.

Do these run an Idle control valve, if so unplug it and see if the revs drop

 

[midnightrider]

First thing to check is the inlet manifold back to the throttle body for air leaks. If air is sneeking in after the throttle body, it will rev higher because it is getting more air than it should.

hi,many thanks for your reply,
im still having the same problem,i have since changed the throttle housing,map sensor,lambda sensor and its still the same,only differencs now is that the revs drop off after about 20 seconds down to about 2500rpm but then go back upto 3000+ rpm and idle irratically up and down between 2500 rpm and about 3000- 3500 rpm have checked for air leaks and cant find any at all,ive run out of things to try now,
any help great appreicated guys,
and many thanks in advance

 

[fishpond47]

might be the cps dirty/faulty/disconnected, throwing the timing out

 

[PUNTOELXBERTONE]

Am having the same problem, all i did is disconnect the idle control valve on the throttle body and works fine, going to try and find a second hand idle control valve as that appears to be faulty. you need to buy the full throttle body with the idle control valve attached, do not take the idle control valve off it or it will bugger it up again as i found.

 

[midnightrider]

hi,thanks for the advice,
i have already changed the whole unit,throttle housing and the idle control unit,but problem is still there,any more advice greatly needed,
and thanks in advance.