Boost Pressure

1. Remove trim cover from passenger side right kick panel.
2. Disconnect vacuum hose from engine control unit.
3. Connect vacuum/pressure gauge using a vacuum "tee" and re-connect to control unit.
4. Road test vehicle and accelerate full throttle from approx. 35 mph. Have a partner riding shotgun to read the gauge.

AUTO TRANS - 2nd gear
MANUAL TRANS - 3rd gear

Fig. 3 Turbocharger Pressure:

5. When vehicle speed reaches 55 mph, note manifold pressure reading on gauge. Repeat test 2 or 3 times and compare readings with chart.

NOTE: Boost pressures appear to increase with increasing altitude. This is not actually the case. The manifold absolute pressure decreases slightly as elevation increases, even during boost conditions. However, ambient pressure drops more rapidly than does the manifold pressure, causing the "gauge pressure" to show an apparent increase in boost pressure.

If boost pressure is greater than specified, check wastegate frequency valve (see WASTEGATE FREQUENCY VALVE in this section). If frequency valve is OK, check if wastegate is stuck closed.

If boost pressure is less than specified, check wastegate frequency valve (see WASTEGATE FREQUENCY VALVE in this section). If frequency valve is OK, check if wastegate is stuck open.