14 February 2017

Holden Cruze JH MY12 - 1.4L iTi 

 

Symptoms

Check engine light illuminated and vehicle lacking power. Vehicle may appear to (or may actually) be going into limp home mode.

Pulling over and cycling the ignition may or may not resolve the issue temporarily.

 

Cause

 

 

Carry out system-wide scan on vehicle

P0299 - ‘Boost Pressure Outside of Specified Range’ will be commonly logged.

Clear fault code and road test vehicle ensuring it is currently at, or reaches normal operating temperature.

Make sure to carry out WOT (Wide-open throttle) test going up a hill or clear section of road.

Graph Boost Pressure PID and observe any abnormal operation (under or overboosting under load)

Check if diagnostic fault code re-logs.

 

Remove turbocharger dump pipe and carefully inspect casting around internal wastegate port for cracks.

 

Remove pneaumatic wastegate actuator and check for side-to-side movement in wastegate shaft.

The video below shows that once the wastegate flap is in the closed position, it can be further rotated, allowing exhaust gas to bleed past the wastegate flap.

 

Check for breakdown or degradation of catalytic converter monolith using a borescope.

The 1.4L iTi engines run 2x catalytic converters, if the front catalytic converter is degraded, the exhaust system should be further dismantled and inspected and components replaced as necessary.

 

Remedy

Supply and fit new turbocharger assembly and catylitic converter/s as necessary.

Ensure all o-rings and gaskets are renewed. It is also recommended to change the water cooling pipe assemblies as shown in the image below.

 

Fill and bleed cooling system, allow engine to heat up, re-tension exhaust manifold nuts and check for oil leaks.

Carry out road test over a full drive cycle and ensure no abnormal conditions are present such as rich/lean mixture conditions or high fuel trims.

 

Mechanic.com.au Quick Tip

(Note that the 1.4L iTi engine mentioned in this article is NOT VGT!)

Three of the most common causes of failure of Variable Geometry Turbochargers

• Carbon/Soot contamination or rusting of the exciter ring or vane mechanism
• Wear between the exciter ring and guide pin (the pin that moves the exciter ring)
• Failure of the control motor or solenoid

Three tips to extend the life of a Variable Geometry Turbocharger

• Ensure the turbocharger gets 'worked' occasionally and that the vehicle is not always driven sedately.
• Ensure the vehicle is regularly serviced and running correctly and is not suffering from incorrect fuel mixtures and that unnecessary DPF regenerations are not carried out on Diesel Engines.
• Avoid storing the vehicle for long periods of time, expecially in coastal areas to prevent rusting of the exciter ring and vane mechanism.

 

 

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