Test and Diagnostic Equipment for Turbochargers

Frequently Asked Questions About Turbocharger Diagnostics

A loss of power, incorrect boost pressure, or oil in the intake or exhaust systems do not automatically mean that the turbocharger is defective. Problems with the boost pressure control system, exhaust system, intake system, or crankcase ventilation system can also cause similar symptoms. Here, we answer common questions about systematic turbocharger diagnostics and the appropriate measurement methods.

• What parameters can be measured during a turbocharger diagnostic test?

  Depending on the test equipment, various pressures in the vicinity of the turbocharger can be measured mechanically.

  These include, for example:

  • Boost pressure
  • Control pressure of the pneumatic boost pressure control system
  • Pressure and vacuum
  • Exhaust back pressure
  • Differential pressure
  • Crankcase pressure

  This allows for the systematic examination not only of the turbocharger itself but also of its technical environment.

• What symptoms might indicate a problem with the turbocharger or its surrounding components?

  Typical reasons for diagnosis may include, for example:

  • Loss of power
  • Insufficient or fluctuating boost pressure
  • Unusual noises
  • Oil in the intake or exhaust system
  • Unusual exhaust behavior
  • Troubleshooting codes related to boost pressure control
  • Deviations between target and actual boost pressure

  However, these symptoms do not automatically indicate a defective turbocharger.

  Faults in the fresh air and intake system, the exhaust system, the pneumatic control system, or the crankcase ventilation system can also cause similar symptoms.

• Why should boost pressure be measured mechanically?

  The engine control unit processes electronic pressure and sensor signals.

  An additional mechanical measurement can help verify the actual pressure in the system.

  This is particularly useful when:

  • electronic readings appear implausible,
  • the fault occurs only under certain load conditions,
  • setpoint and actual values differ,
  • a mechanical fault is suspected.

  Mechanical measurement thus complements electronic vehicle diagnostics.

• What is boost pressure?

  Boost pressure is the pressure at which the turbocharger supplies compressed air to the engine.
  
  The actual pressure required depends, among other things, on the engine, load, RPM, and boost pressure control.
  
  Therefore, there is no single boost pressure that applies to all vehicles.
  
  The measured values must be compared with the specifications provided by the respective vehicle manufacturer.

• What is the control pressure for the turbocharger control system?

  In pneumatically controlled turbocharger systems, a pressure or vacuum signal is used to actuate the control mechanism.
  
  A suitable test device can be used to verify whether this control pressure is present and whether it varies as intended for the specific operating condition.
  
  This makes it possible to determine whether a problem lies, for example, in the turbocharger itself or in its pneumatic control system.

• What does “pneumatic boost pressure control” mean?

  In a pneumatic boost pressure control system, a vacuum or pressure reservoir is used to actuate the turbocharger’s control mechanism.
  
  Depending on the turbocharger system, this can affect, for example, a wastegate or variable turbine geometry.
  
  Faults in hoses, valves, pressure cells, or the vacuum supply can therefore result in incorrect boost pressure, even though the turbocharger itself is mechanically functional.

• What is exhaust back pressure?

  Exhaust backpressure is the pressure against which the exhaust gases must flow through the exhaust system.

  Unusually high backpressure may indicate that the exhaust flow is obstructed.

  Possible causes may lie, for example, in the exhaust system or the exhaust aftertreatment system.

  Exhaust pressure testers are available for precise measurement.

• Why is exhaust backpressure important for turbocharger diagnostics?

  The turbocharger's turbine is driven by the exhaust gas flow.
  
  Unusual resistance in the exhaust system can therefore affect the operating behavior of the turbocharger and the engine.
  
  In the event of a loss of power or implausible boost pressure, measuring exhaust backpressure can therefore be an important additional diagnostic parameter.

• What is crankcase pressure?

  During engine operation, blow-by gases, among other things, are generated in the crankcase.
  
  The crankcase ventilation system vents these gases in a controlled manner.
  
  If the ventilation system is not functioning properly or if an unusually large amount of blow-by is generated, the pressure in the crankcase may change.
  
  This pressure—or vacuum—can be checked directly using a suitable measuring device.

• Why is crankcase pressure important in the event of suspected turbocharger failure?

  Oil must be able to drain from the turbocharger toward the engine or oil pan as freely as possible.

  Unfavorable crankcase pressure can impair this oil drainage.

  This can lead to symptoms such as oil in the intake or exhaust systems, even though the turbocharger seal is not necessarily the original cause of the problem.

  A crankcase pressure measurement can therefore help prevent unnecessary turbocharger replacement.

• Can oil in the intake tract automatically be considered a sign of turbocharger damage?

  No.
  
  Oil in the intake tract can have various causes.
  
  In addition to the turbocharger, the crankcase ventilation system, oil separator, or other components may also play a role.
  
  Therefore, the entire area surrounding the turbocharger should be inspected before concluding that the turbocharger itself is the cause.

• Can a clogged exhaust system cause boost pressure problems?

  Yes.

  Increased flow resistance on the exhaust side can affect the operating characteristics of the engine and turbocharger.

  If this type of fault is observed, the exhaust back pressure should also be measured.

  The measured values must be compared with the vehicle manufacturer's specifications.

• Can a leaky intercooler hose cause damage similar to that caused by a turbocharger failure?

  Yes.

  If compressed air escapes between the turbocharger and the engine, the required boost pressure cannot be achieved.

  This can manifest itself, for example, as a loss of power or fluctuations in boost pressure.

  If these symptoms occur, a leak test of the fresh air and intake systems should therefore also be performed.

• How can you tell the difference between a turbocharger malfunction and a problem with the surrounding system?

  A systematic diagnosis considers multiple parameters and systems together.

  These may include:

  1. electronic vehicle diagnostics and fault memory
  2. mechanical boost pressure measurement
  3. inspection of the pneumatic boost pressure control system
  4. exhaust backpressure measurement
  5. crankcase pressure measurement
  6. Leak testing of the intake and charge air systems
  7. Inspection of the oil supply and oil drainage

  This allows the cause of the fault to be narrowed down more precisely before components are replaced.

• Can the turbocharger be tested during a test drive?

  Using test equipment designed for this purpose and properly routed test leads, pressure measurements can also be performed under actual driving and load conditions.
  
  This can be helpful if a fault occurs exclusively under load.
  
  The test setup must be configured so that neither the driver nor vehicle operation is impaired and the leads do not come into contact with hot or moving components.

• What is the difference between DT 01, TDU 03, and TDU 04?

  The devices cover a range of diagnostic functions.

  The DT 01 is specifically designed for rapid diagnostic testing of:

  • crankcase pressure
  • exhaust backpressure
  • pneumatic boost pressure control.

  The TDU 03 also enables comprehensive mechanical measurement of boost pressure, control pressure, differential pressure or exhaust backpressure, and crankcase pressure.

  The TDU 04 is a more compact solution for measuring pressure and vacuum in the field of turbocharger diagnostics.

  Which device is suitable depends on the desired scope of testing.

• Why is the DT 01 available in both universal and vehicle-specific versions?

  To measure crankcase pressure, the test device must be properly connected to the engine or the oil fill area.
  
  For this reason, both universal and vehicle-specific versions are available.
  
  Leitenberger, for example, offers special DT-01 models for VW, Ford, and Stellantis vehicles, as well as a universal, adapter-free basic model.

• Can an OBD diagnostic tester be replaced by a turbocharger tester?

  No.
  
  Electronic and mechanical diagnostics answer different questions.
  
  For example, the OBD tester provides error codes, sensor readings, and ECU information.
  
  The mechanical tester, on the other hand, displays the actual pressure or vacuum present.
  
  Combining both methods is often particularly informative.

• What testing equipment is needed to complete a professional turbocharger diagnosis?

  Depending on the type of malfunction, the following may also be useful:

  • Pressure and leak testers for the exhaust system
  • Leak testers for the fresh air and intake systems
  • Crankcase pressure gauges for blow-by gases
  • Electronic vehicle diagnostics

  You can find additional solutions under Test and Diagnostic Equipment for Exhaust Systems.