Charge Air Pressure Bypass Valve, Testing

Charge Air Pressure Bypass Valve, Testing

NOTE:
- The charge air pressure bypass valve is located upstream of the turbocharger. It is opened by vacuum from the electrically operated Recirculating valve for turbocharger -N249- when the engine is on overrun, under part load, or when idling. This disperses the pressurized air (charge air pressure) upstream of the throttle valve, and thus keeps the turbocharger rotating at a higher speed.
- Check the charge air pressure bypass valve if the engine is not producing full power, or jerking when the throttle is opened and closed.

Special tools, testers and auxiliary items required







- V.A.G 1390 Vacuum pump

Work sequence







- Connect vacuum pump V.A.G 1390 to charge air pressure bypass valve.
- Operate vacuum pump.

Charge air pressure bypass valve should open (arrow).

- Operate air vent valve on vacuum pump after about 30 seconds.

Charge air pressure bypass valve should close (arrow).

If the charge air pressure bypass valve does not open and close as specified, or if the valve plate does not seal properly when the valve is closed:

- Replace charge air pressure bypass valve. Secure connections on valve with screw-type clips.