Sad Operation

[lagonda 42]

After 2 year's off the road my CTi's now up & running once more & is running fine, now I'm sorting out the rough edges!

It has been starting fine but needed some throttle prodding to stop it stalling. After a few seconds, it would idle at around 1000rpm. Then it would drive OK, but after 5 minutes or so it would stall as idle would drop too low. After another few minutes it would then idle fine, at about 800-900rpm.

The car has always run like this, so I don't know how it should run when started from cold.

It seems to me that the SAD would benefit from attention. Took it off & found the shutter took around 4 minutes to close. There is a small stud with nut & locking washer which sits in a small slot, allowing some adjustment. This was more or less at one end of the slot, so I moved it to the other end of the slot. Now it takes around 12 minutes to close fully ... that said it is almost fully closed after 8 odd minutes, it seems to take a long time for the last crack of light to disappear!

Fitted back on the car, I now find it starts fine & idles straight away at 1000rpm. After around 5 seconds, this starts increasing, rising to 1700rpm. After 8-10 minutes this drops back to around 900rpm, & the tendency to stall inbetween times has gone.

So ... is this how it is supposed to be, or do I need to do some fine tuning?!

[Ahl 4]

That sounds roughly about right.

 

These cars should idle at 1000rpm when warm - they aren't happy idling much lower due to the big cam in them.

 

Then, when cold, the SAD should raise the idle to about 1400-1500rpm, though I think every sad is different!

The main thing is to get the warm idle set properly first, then address the SAD after that.

 

You should also make sure that you don't have any air leaks and that the induction tubing, AFM and idle and air bypass (AFM) screws are clean underneath.

[lagonda 42]

Have cleaned out all tubing, throttle body and inlet manifold ... only job left to do is cleaning the adjustment screw on the AFM. Haven't done that yet as car had been set up with that as it was, & priority was to ensure car started & ran OK. Have been experimenting with ignition timing as the head being skimmed, even only slightly, meant this would have been wrong if set as before. As the ignition timing affects the idle speed I haven't bothered setting idle too precisely yet.

So it seems I could wind the adjustment in a bit on the SAD if I aim for 1400-1500 cold idle, provided that doesn't re-introduce the stalling which previously occurred part way through warm-up.

Is the initial start at 1000rpm idle, soon rising, what I should expect, or should it start at high idle immediately?

I know what you say about the benefits of high idle. Thought this was because the relatively crude electronics involved with the AFM couldn't read the airflow accurately at low idle, meaning rough idling. Strangely one thing I can say in my car's favour is that idle, at least hot idle, has always been very good and smooth, even down at 700rpm.