Checking Boost Pressure While Driving Vehicle
CAUTION:
Excessive boost pressure can cause severe permanent engine damage.
- Remove turbocharger control valve from air cleaner housing. See BOOST PRESSURE CONTROL VALVE in REMOVAL, OVERHAUL & INSTALLATION - S40 & V40. Remove Red-marked hose from turbocharger control valve. If hose cannot be pulled away, cut it off the control valve.
- Connect Manometer (999-5230) and extension hose to attachment point of Red-marked hose on turbocharger control valve using a "T" intersection. See Fig 1.
- Route hose and manometer inside vehicle and hang manometer vertically. Ensure that vehicle hood can be fully closed.CAUTION: DO NOT hold brake pedal for more than 5 seconds or severe brake system damage may result.
- Drive vehicle in second gear at approximately 1,800 RPM. Press accelerator pedal to Wide Open Throttle (WOT) and run engine up to 5,500 RPM. When 5,500 RPM is reached press brake pedal to create load on engine. This will create maximum boost pressure. Hold brake pedal for approximately 5 seconds and observe manometer. Boost pressure should be 7.25-8.70 psi (50-60 kPa). If pressure is not as specified, adjust boost pressure control valve. See BOOST PRESSURE CONTROL VALVE
in ON-VEHICLE ADJUSTMENTS - S40 & V40 article. Repeat procedure after adjustment. If value is OK, go to next step.NOTE: DTC ECM-2D will be stored when turbocharger electrical connector is disconnected.
- Disconnect electrical connector for turbocharger control valve. Repeat procedure in step 4. This measures basic boost pressure with the vehicle in "limp-home" mode. Boost pressure should be 2.90-4.35 psi (20-30 kPa). If pressure is not as specified, go to next step. If value is OK, remove pressure testing equipment and connect turbocharger control valve hose and connector.
- Retrieve and diagnose DTCs. Check turbocharger piping for leaks. See INTAKE SYSTEM LEAK TEST . Check for blockage and unusual noises. See PRELIMINARY CHECKS . Check that engine mechanical condition is good. Check for proper fuel octane and emission system function. Repair as necessary and repeat procedure in step 4. Go to next step.
- If boost pressure is correct, but there is still power dissipation, replace ECM with a known good unit. See ENGINE CONTROL MODULE in REMOVAL & INSTALLATION - S40 & V40 article. Repeat procedure in step 4. If boost pressure is now OK, remove pressure testing equipment and connect turbocharger control valve hose and connector. Retrieve and diagnose DTCs. If value is not OK, go to next step.
- Replace turbocharger. See TURBOCHARGER in REMOVAL & INSTALLATION - S40 & V40 article.