New Guy, long time lurker.
1987 XJS-C - HE V12, she is a Targa Top Beauty with only 56k.
Still hunting even after a Lucas AAV replacement.
Still idles high, higher with the new AAV versus the old.
Here is the clue.
When I place my hand over the driver side air intake flared end, you can feel the suction.
When I block the end, the hunting disappears and idles perfectly immediately.
When I place my hand over the passenger side intake air flared end, barely any suction.
When I block this side no changes in the hunting.
Vacuum issue? Exact location?
Please share your thoughts, I am close on this.
Appreciate any and all help.
JGCT

 

I just red here on this forum that the strong suction on one side and weak on ther is expected when idling.
But this still doesn't explain why the "hunting" will disappear and the idling will reduce greatly.
Hmmmm

 

The hunting....how much is it?

A big swing like 600 rpm to 1500 rpm?

Or smaller, like 600 rpm to 800 rpm?

Are the throttles synchronized and throttle blades set at .002" ? No mechanical sticking in the cable or linkages?

The bolts holding the air cleaner housings onto the throttle bodies tight?

Cheers
DD

 

Hi Doug, thanks for the reply.
The hunting is a big swing 600 to 1500 is eactly the range.
The throttle is synced and blades checked and linkages are all free.
The air cleaner bolts on both sides are tight.

Something about the blocking the flared end driver side air intake tube is "fixing" the hunting and the idle.
I am close to getting this all worked out.
Just trying to figure this last item.

 

Can you take the cover off the air intake and block the tube to the overrun valve? Its might be a bit loose and letting extra air in sometimes.

 

I had recently taken off both air filter housings and inspected all the connections.
Bolts are snug. I will double check the tube to the overun valve.
Thanks for the idea and the thanks for the reply.