In modern vehicles, multiple electro-pneumatic valves are usually fitted. They switch and control intake manifolds, exhaust gas flaps, air conditioning, secondary air, EGR valves and a wide range of comfort and safety functions.
If they fail, professional repair is inevitable. Especially because they are frequently in hard to access areas of the engine compartment. Professional diagnostics in the repair shop and the use of high quality spare parts are always advisable.
Electro-pneumatic valves fulfil the same function in a vehicle’s pneumatic system as switches and dimmers in an electrical circuit. For example, in conjunction with an actuator they enable flaps to be operated or a turbocharger to be controlled.
Switchover valves can be found in a vehicle wherever engine components have to be controlled pneumatically: boost pressure control valves in TDI engines, throttle valves for exhaust gas recirculation in SDI engines, engine water cooler frames, hydraulic engine mounts and exhaust gas flaps on the exhaust post-silencer.
By contrast, pressure transducers are used for EGR systems and VTG turbochargers. For other media, electric valves such as recirculating air valves, activated carbon filter valves, fuel isolating valves or control valves for camshaft adjustment are also used in modern vehicles.
Causes of damage
Because of the numerous uses of electro-pneumatic valves in all kinds of different systems in a vehicle, the symptoms indicating a faulty or failed valve are very diverse: lack of power, “turbo lag” on turbochargers, black smoke, jerking or limp home function, in the event of valve malfunctions in the EGR system.
The most frequent causes of failure are water and dirt getting into the control vacuum system. This can be due to leaking or broken hose connections.
High ambient temperatures can also cause sporadic malfunctions. In rare cases, malfunctions occur due to mixed up connection hoses. Likewise, a defective vacuum pump can deliver insufficient vacuum for correct actuation.
Expert view needed
However, as the OBD (on-board diagnostics) does not monitor the function of electro-pneumatic valves and only checks for current continuity, short circuit and earth connection, faults cannot always be definitively identified – in these cases malfunctions are often incorrectly attributed to other components.
For this reason, an expert with system know-how is needed to scrutinise the faults displayed and perform an intensive search for the causes.
The tightness of an electro-pneumatic valve can very easily be checked using a vacuum hand pump. In many cases, an easy electrical test on an electro-pneumatic valve can be carried out using any standard multimeter.
Pierburg quality products
Just as important as professional diagnostics is the use of high quality spare parts. This is the only way to guarantee the long-term success of a repair.
Pierburg is the European market leader for solenoid valves, the global market leader for recirculating air technology for turbochargers, and as an OE supplier it produces more than 350 different standard valves.
For more information on Pierburg electric valves contact hsy or call 1300 133 129