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[Kornknarr]

Heureka!

Finally I found it. The secret of the thing is unfolded here: http://www.meeknet.co.uk/e31/E31_840..._Tick-Over.htm

No wonder neither you guys nor the British knew what it was, it's only found on German and (probably by laziness on BMW's part) for example Swedish cars. "So, I blocked the T-piece where the cap fell off and was pleasantly surprised to find that the tick-over was perfect - and more interestingly, the error codes didn't return and the adaptations settled at very low figures. Only models for certain countries (Germany for instance) have anything other than a blanking cap fitted to the T-piece. In Germany there is a 'disturbance air valve' - Reinhard tells me that the valve is used for the emissions test, opening the valve allows un-metered air into the manifold which the ECU should be able to compensate for:"

Thx for help and input. One more riddle solved!

Per

[BenFenner]

Great work Kornknarr. Now we have a new section in The Manifesto.


Disturbance Air Valve (emissions test MAF by-pass unmetered air test fuel trim test)
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