Revs surging when car is warm

[garfa]

Hi All,

Current my SS does not idel smoothly when cold. It seems to twitch (as a V8 does) but this is more frequent of late. Also and more concerning, when the car is warm (30mins driving) the revs can surge at idle by upto 200RPM.
Is this a concern? Could it be a vacume leak?
Hoden have just fobed me off as "the gen3s idle rough, dont worry about it" -not good enough boys!

So all, what do you think? Any leads as to the problem cause?

 

[DaggaZ]

i had the same problem with my vt v6. do the revs drop about 100 then rev 200 over?

i would like to know the answer to this to..

 

[sp001in]

Inlet air temperature. changes in temp will increase and decrease idle. Your exhaust bipass solenoid may not be functioning correctly. therefore continue to allow heat from exhaust gases to warm the inlet manifold. dropping the revs. then switching allow colder air therefore increasing the revs.

Dirty air filter, air filter box not clipped probably will allow rushes of extra air, if the lid moves after acceleration or braking.