My 1991 V12 convertible is in excellent condition and always runs great. Recently on a cold start up once it reaches temperature it surges up and down at idle. Once in gear to drive, the surge stops unless in park or neutral. There are no vacuum leaks to be found. Is this the telltale symptoms of my AAV sticking? I'm thinking of having Jonas Loda rebuild it this winter.

 

Yes, classic sign of the AAV sticking open.

 

It could also be a vacuum leak. There are several ways to check for one. You can use carb cleaner and spray the suspected areas or use a propane torch (unlit).

 

OR, the TPS is out of "idle range", which is getting now with age.

 

Of the three solutions suggested, don’t be surprised if the problem is all three.

 

If the OP removes the B bank airbox and closes up the air passage to the AAV, then runs the car, if the surging stops when warmed up, it is the AAV, or its idle adjustment.

But, do NOT do this without first disconnecting the vent tube from the dizzy to the AAV pipe, or oil can be sucked up through the dizzy.

 

Hi Anglicomarine

Certainly not uncommon for the Piston in the AAV to stick if the Car has not been used for a while and its also not uncommon for that very same Piston to free itself off and then start working as it should after a bit of road use, as always seems to happen to mine after a Winter layup

Although you can also help things along by taking off the Intake Pipe and giving the inside a really good squirt of WD40

Be Careful not to break the Pipe as they do get very brittle due to the heat