Sticky idle problem on 3.2

[DJB]

Hi All,

Some of you may remember my posts on a cold idle problem, which I have struggled to rectify. Effectively my 86 Cab, wouldn't idle when cold without a little assistance from the heel and toe when stopping.

Having read some threads recently about manual adjustments to idle speed (taboo in Bentley) I decided to give it a go since I was (warm) idling @ only 700rpm.

I adjusted the idle screw (after removing the rubber cap) to an even 800 RPM (warm) and took her for a spin - no problems.

The next day on start up she'd idle @ 2500 rpm when cold and did not alter when warmer. However a quick blip of the throttle would have her return to 800 rpm. However she would not return without the blip.

When cold, I also noticed a degree of hunting between 1200 and 1350 rpm at idle?

The obvious question is, did I readjust the idle screw to a its original position - no not as yet. As it was or seemed to be OK. Do you think it is a simple matter of a readjustment, do I have a sticky throttle problem, or is it a potential problem with the 'brain'

Your thoughts are appreciated.


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[Rick Lee]

What does your accelerator pedal feel like? Your throttle cable or pedal cluster could be getting stiff. I had this happen in an '87 BMW. In cold weather, it sometimes does idle a little high until warm. Today was the first frost where I live and my '87 Carrera did just fine. I keep my idle set at about 900-950 rpms.

[DJB]

Thanks Richard,

The throttle feels fine and only changed once I made the adjustment to the idle speed. I will crank back the idle speed again tonight.

It was idling far too low - what is the best idle speed in members opinion for an 86 3.2?

[ChrisBennet]

When you adjusted the idle did you disable the idle stabilizer valve by jumping B & C in the test socket?
On your '88 the idle speed is controlled by the DME (computer). It uses the idle stabilizer valve to control how much air is routed around the closed throttle. The idle adjustment screw is used to set the uncompensated or "default" idle speed and the computer then uses the idle stabilizer to add extra air as needed.
If the idle stabilizer valve is not working or sticking the DME won't be able to compensate and you can get a low idle speed. You can remove it and clean it with some carb cleaner. That works sometimes but in the end you'll probably have to replace the ISV. -Chris