Jaguar XJS 12 - 1986 idle up-dpwn

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Sep 8, 2016 | 05:35 AM

Daniel Bar-Tal

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Junior Member

Joined: Sep 2016

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Jaguar XJS 12 - 1986 idle up-dpwn

Hello
looking for reason of idle up-down constantly.("p" position)
Your attention and cooperation in this matter will be greatly appreciated.
Daniel

Sep 8, 2016 | 05:47 AM

Grant Francis

Joined: Feb 2010

Posts: 28,829

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From: Adelaide Stralia

Firstly welcome to the Forum.

The list could be long but the basics I have dealt with are:

AAV jammed, about 98% of V12's have this issue.
TPS setting out of idle fuel map range, age related, and common enough to mention.
The common Black Goo inside each throttle body, VERY common, and needs wiping out at each oil change.
Spark plugs are gapped wrongly, VERY common.