There comes a time in the life of a turbocharger when it no longer performs like it once did. The problem, of course, is figuring out when it’s the turbo and when it’s something else.

A turbo’s basic purpose is to boost power, so when an otherwise healthy engine suddenly becomes anemic, it often (but not always) means turbo trouble. Some of the symptoms that may indicate a sick turbo include a loss of power, loss of boost pressure, turbo noise, increased oil consumption and oil fouled spark plugs, or excessive exhaust smoking on diesel engines.

The easiest way to diagnose a weak turbo is to observe the vacuum/boost gauge or boost indicator light. If it doesn’t show normal boost at full throttle (typically 9 to 14 psi for many OEM turbo systems), better get the toolbox. Be warned, however, that excessive backpressure (often due to a clogged catalytic converter) can also prevent the turbo from developing its normal boost pressure.

Turbocharger Wastegate Inspection
Observe the operation of the wastegate. If the wastegate does not move at all, overboost and detonation is the usual complaint. But if it is hanging up and does not close fully, it will bleed off exhaust pressure from the turbine wheel and prevent the turbocharger ...