Boost Pressure
- To test the turbocharging system, use a pressure gauge (VW 1397). The gauge is equipped with a valve which locks pressure measurement when closed. Engine must be at operating temperature. Ensure there are no leaks on intake or exhaust side.
- Attach gauge to the boost pressure line at the fuel injection pump, using "T" fitting supplied with gauge. Use hose clamps at all connections to avoid low readings.
- Boost pressure can only be tested on a chassis dynamometer or through road testing. Carry the gauge inside car by routing the hose out right rear corner of hood and into passenger side vent wing window. Measure boost pressure with engine at full throttle.
- On dynamometer, check boost pressure at 4000 RPM. Place manual transmission in 3rd gear and automatic transmission in 2nd range. On road test, place manual transmission in 2nd gear and automatic transmission in 1st range. Hold road speed at 60 MPH with foot brake.
- Boost pressure should be 9.3-10.2 psi (.65-.72 kg/cm2 ). If boost pressure is too high, replace turbocharger. If pressure is too low, disconnect blow-off valve hose from intake air hose.
- Plug air hose. Repeat boost pressure test. If pressure is good, replace blow-off valve. If pressure is still not good, replace turbocharger.