Holden Commodore Problems

It doesn’t have a cam-timing belt; it uses a chain that doesn’t need regular servicing like a belt does.

It depends on the gradient, the idle speed etc., but generally an auto will sit on a slight gradient without rolling back. The idle speed could be a little low. But I wouldn't be concerned about it if it does roll back, it shouldn't have any effect on take-off when you're out driving and have to stop on a hill.

A possible cause is a broken spline in the reaction shell, but you need to consult an auto trans specialist.

Holden’s own recommendation is that E10 is fine for your model. There’s no reason to believe E10 would damage your engine.

The best system for your car is a vapour-injection one and IMPCO was the system used by Holden for the factory-fitted cars. But there are lots of other systems that would also perform well. All systems are made in Italy, no matter the brand. Choose a well-known brand and an experienced installer, and ask the installer for references from other owners who have had similar systems fitted. The vapour-injection systems are more expensive than the older technology venturi/mixer ones, and on average are priced around $4500.

Check the relay and its connections, and check the earth connection.

The first thing is to go over the car and identify anything on it that might be contributing to fuel consumption. Look at the condition of the tyres and run slightly higher tyre pressure than recommended by Holden, remove any roof rack that might be fitted, same with any other body additions you might have made. Don’t carry any extra weight. Also make sure the engine is in tip-top shape regards plugs, leads, injectors, air cleaner etc. Also look at your driving style to see if you can make changes there to save fuel. Extractors, chips and the like can make small improvements, but I doubt it would be enough to cover your costs. The most viable is LPG, but it would take up to two years on average to get your money back.

If your Commodore has IRS you’ve got a tyre-eater on your hands and it would be worth talking to a suspension specialist about fitting a kit to the rear suspension to control the toe-in. Tyre specialists also recommend that you regularly rotate your tyres — 10,000 km is the interval they suggest — and have the alignment checked and reset every 20,000 km. Alignment is often neglected, but is an important contributor to tyre life and can be knocked out simply by hitting a kerb or a pothole. After doing that you could fit a Pirelli or a Michelin tyre, which should give you better tyre life.

It could be a faulty shift solenoid or a problem with the throttle position sensor. Take it to an auto trans specialist who should be able to diagnose the problem for you.

It sounds like a fault with an engine sensor or its connections. Check the crank angle sensor.