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Checking air recirculation valve for turbocharger N249 > < Checking turbocharger and charge pressure control

A3 Mk1

Checking mechanical air recirculation valve
Checking mechanical air recirculation valve
  Note
t  The mechanical air recirculation valve is located upstream of the turbocharger. It is opened by vacuum during overrun, at idle and at part throttle. This dissipates the charge pressure upstream of the throttle valve and maintains a higher turbocharger speed.
t  The mechanical air recirculation valve is controlled via the turbocharger air recirculation valve -N249-.
t  Check mechanical air recirculation valve in the event of loss of power or jolting during load change.
Special tools and workshop equipment required
   
t  Hand vacuum pump with accessories -V.A.G 1390-
  W00-0515
Procedure
–  Take off engine cover panel -arrows-.
  A10-0515
–  Detach vacuum hose at air recirculation valve.
–  Connect hand vacuum pump -V.A.G 1390- to air recirculation valve.
–  Use hand vacuum pump to generate vacuum.
l  Air recirculation valve should open -arrow-
–  Operate vent valve on hand vacuum pump after approx. 30 seconds.
l  Air recirculation valve should close -arrow-.
If air recirculation valve does not open/close or if valve plate does not provide a tight closure when air recirculation valve is closed:
–  Renew air recirculation valve.
  Note
Secure all hose connections with the correct type of hose clips (same as original equipment) → Parts catalogue.
  V21-0074

Checking air recirculation valve for turbocharger N249 > < Checking turbocharger and charge pressure control