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I have a 1996 Holden Astra 1.6 Automatic with an intermittent stalling and rough idling problem which has been ongoing for 18 months. During the last three months the ERG valve has been replaced and Holden have updated the computer software - but the problem still persists.

The stalling occurs when I have slowed right down or stopped and then pressure is applied to the accelerator. So far the initial momentum has got me out of the line of other traffic.

Nothing has ever registered on the computer codes. Holden is no interested in investigating further. My mechanic is stumped.

Please can you help?

Cathy

From the "Ask Jack" archives - 14 December 2009

Intermittent problems are always the worst to try and diagnose and fix, so I have some sympathy for the local Holden dealer on this one.

I have thrown your question to the technical brains within the AA including one of my most trusted sources within the road service breakdown team, in an effort to give your mechanic some help in sorting the problem out.

No guarantees, but the information below may help.

Have a look at the PCV (positive crankcase ventilation) valve and its port in the manifold to ensure they are not blocked. The management system is calibrated to allow a certain amount of air to flow through the PCV system at idle, obviously if the valve or the port itself is blocked, this could affect the idle speed of the engine. The same thing applies to the airways in the throttle body; they should be clean and clear.

We are assuming that the EGR valve, being new, is functioning correctly. If its vacuum operated, the vacuum switch vent should be checked to ensure that it's clean and clear.

These are faults that we believe could occur without introducing a fault code in the engine management computer.

Hope this helps Cathy.

Let me know either way.