Date: Sun, 24 Jul 2005 13:00:05 +0200
From: MH <>
Subject: Re: APC Guage does not move at all...

> Hi...Am now the proud owner of an 87 900 Turbo...and it rocks!... Great. 8 valve? I had one of those... > But, the APC Gauge in the dashboard does not move at all....It's stuck in > the white area at about the 10 o'clock position and just does not move...So > does this mean the turbo is not working and how do I fix this 'opportunity' If 'it rocks', the turbo probably IS working, if you floor it. But... The APC gauge is connected with a rubber vacuum hose to a pressure transducer and on to the inlet manifold. If the turbo pressure is too high (in the red zone) the pressure transducer will send a signal to the APC computer and that will switch off the fuel pump or open the solenoid valve to actuate the wastegate. If you feel that the turbo IS working, then my guess is that the rubber hose from the guage to the pressure transducer is torn or disconnected, and the guage only indicates atmospheric pressure. Then also there will be a vacuum/pressure leak and the pressure transducer may never kick in. You may also hear hissing sounds coming from under the dashboard. If you disconnect the rubber hose from the inlet manifold and suck/blow on it, the guage sould move. If you can blow/suck right through the hose without much resistance, it is disconnected somewhere. The guage is a very simple thing, so not much can go wrong with it. If you take out the speaker grille in the dashboard (driver side - either left or right) you should be able to see/feel if the hose connection on the back of the APC/ instrument cluster is OK. IIRC the pressure transducer is behind the kickpanel under the dashboard. See also the turbo category at -- MH '72 97 '77 96 '78 95 '79 96 '91 900i

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