XJ6 & XJ12 Series I, II & III 1968-1992

XJ6 EFI cold start heavy hunting Up&Down

Old 03-28-2009, 03:42 PM
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I have been told that the up-down hunting during idling is the classic symptom of a sticking Auxiliary Air Valve.

One solution I have heard about is a Techtron 'tune-up', which entails adding the Techtron stuff to each tank, driving around for 2 hours, accelerating to 90 mph, then shifting to 2nd gear. They say you should see a cloud of black smoke in the rear. All the crud was burnt off.

I've never done it, so I cannot swear by it. but others do. I just don't believe them.

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