I've got a 1.1 55s n reg and when it is parked. when you rev the car at high
revs the starts to blip revs not stable but only at high revs. The car is slighty
using more fuel . Only not vey often the cam belt tensoner will sweak will this casue it. thanak for any help

update if i rev it with pedel in car it does it but if i rev it under the bonet it does not do it strange or what so how can it be the accelerator cable

How high are we talking here.....6.5k?

dont know dont have a rev counter but it is at its limits almost i think

Reving that engine like that whilst stood is asking for trouble, chances are you've hitting the rev limiter doing so whilst engine in not under load will kill your engine quickly

if you have your head under the bonnet pulling the cable you cannot rev it as high as machanical sympathy subconciously kicks in just before your ears start to bleed. If you rev it with the throttle peddle and the bonnet shut you can acheive higher revs as FIAT's are desined in such a way that when you blow up the engine the valves jump out of the engine and dance the tango on the bonnet, this is only possible of course if the bonnet is closed

Now stop bloody reving it and start driving it that is what it is designed for after all

yes but it is useing more fuel and it sorts of flat spots whil you are driving
and i dont know what it is

i think its back firing out the back box but only very slighty

i think it could the valves need re shiming as they are clicking when cold