xjs v12 5.3 1990, how does one adjust idle speed (slow it down slightly)

 

Geoff,

I've moved your question from General Tech Help to XJS forum. Members with the same model are more likely to see it here.

Graham

 

Look at page 33 of the document below. You adjust the Auxiliary air valve (AAV) to adjust idle speed. The document is for the Lucas distributor variant, you have Marelli, but all of the throttle adjustments and idle speed adjustments in the document apply.
http://jagrepair.com/images/AutoRepa...XJS%201992.pdf

 

You are looking for this item, which is at the cabin end of the B bank of the engine (UK passenger side), just lower than the inlet manifold itself. Turn the bolt inwards to reduce the idle speed.

This pic is shot with the inlet manifolds off.

 

as a caveat,
ensure both TB's are set to 2 thou , and no tightness in the linkage, and ensure the pivot bushes are in good condition before adjusting the idle at the AAV , which should only be done for ' hot idle' as cold idle will see it around the 1200 revs for a few minutes, which is what its there for

BB