Is there an IAC on a series 3? (1987 VDP 4.2)

Ok so I have “a friend” who is stumped. Is there an idle control valve (IAC) on series 3. I don’t see any reference to it but if you go online, all these parts suppliers say there is one.
Below is the pic. I don’t see anywhere this would go in the 4.2.

Any takers? :slight_smile:

Nope. Not in the modern day sense.

The ‘idle air control’ is by way of a manually adjusted screw in the air distribution block.

I’ll try to find a pic for you

Cheers
DD

The air distribution block is the odd looking aluminum casting forward of the throttle body. The adjustment screw takes a hex key (or, in this pic, a hex bit with a wrench)

image

Cheers
DD

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Some cars were fitted with an idle enhance control to counter idle drop with AC ‘on’, Jeffrey…

It’s rare to find and is just a throttle bypass controlled by a valve, much like an AAV, electrically controlled ‘on/off’. It does not involve anything like the picture shows - and as Doug says; idle is adjusted by a simple idle screw regulating air bypass…

The gadget shown seems to be associated with fluid rather than air that controls idle…

Frank
xj6 85 Sov Europe (UK/NZ)
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Thanks all for your very detailed reponses. Kind of figured this was the case. In the picture above, does that idle control need to be cleaned out from time to time? Looks like it would.

Jeff - the picture you posted, of an (Idle Air Control) IAC looks like the type used on many 80’s and 90’s GMC and Chevrolet type engines - normal electrically controlled and placed in the area of the throttle body air stream.

I agree- It’s strange because when you search for it it comes up on reputable sites as a part-match for series 3.

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It’s the same as the RH fuel return valve and bypasses the AAV. A wire is provided in the front right corner of the engine compartment, operates with the compressor clutch, dealer retrofit as far as I know.

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Can’t hurt. A clue is the idle speed adjustment having no effect

Cheers
DD

Technically speaking there is an Idle air controller on the series 3. Formally its called the Auxiliary Air Valve. The valve you posted is a stepper based IAC that can vary the air with an electrical H-bridge and controller (sometimes included inside aftermarket ecus) but the Jag unit is a Pulse width controlled unit that varies how much its open from the length of the pulse signal the ecu sends out.

The AAV on series 3 is not controlled by the ECU, Derek - it is controlled by heat. Nor is any air ingress controlled by the ECU - it just responds to air flow data…

Frank
xj6 85 Sov Europe (UK/NZ)
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Thanks all. In any case- mystery solved:)