Idle speed adjustment

[knowlesp]

I have just got the car back from having a new aircon compressor fitted and it won't idle when its hot.
It runs at about 500 r.p.m but dies as soon as it gets a load, like steering or air con cutting in.
I can follow the manuals, but they just say 'set the speed to 750 rpm'
Which way do I turn the auxiliary air valve screw to speed up v. slow down?
It won't be easy to reach when it's hot!!
(TWR 5.3l with manual gearbox)

[Brakebuster]

Hi and welcome

adjusting the idle is quite easy , and you shouldnt burn yourself

firstly , get the right tool for the adjustment screw on the AAV and test fit while cold , then when the engine is running and to temperature ( you know this when the fan kicks in ), turning the screw clockwise ( tightening in ) will drop the revs gradually , turn the screw anticlockwise ( loosening out) will increase the revs, this happens because you are opening the adjustment letting in more air

during warmup the V12 will suck more air from the left air intake untill at running temperature as the AAV bypasses the TB on that side and sends it through the ballance pipe at the back of the intake manifolds

dont forget , you also have an 'anti-stall ' relay fitted that must be checked , as in good condition the V12 should never really stall........

did the car run right before the work was carried out, i would possibly contact the garage and ask them to investigate at their cost ?

also wise to have a good look round the engine, as a wire or sensor may not be connected

hope this helps

BB

[BigCatXJS]

A long while ago, I adjusted my AAV as the garage had set the idle at 750 rpm BEFORE the V12 had fully warmed-up. Not good, as when in heavy traffic the idle (with Air Con running - it was a hot day) was around 450 rpm!!! So she did stall a few times. However, a quick adjustment of the AAV when the engine was hot soon sorted this. Screw inwards to reduce rpm, screw outwards to increase rpms (from memory).

Cheers, Rich