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.

The increase in consumption you report is certainly higher than would be expected, but that could be because you were towing. Try it again in normal day-to-day driving and see what you get. The expected increase in consumption is about three per cent and that should be offset by the lower price of E10.

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

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.

Holden’s advice is that you can use E10 petrol in your car.

It sounds like it’s not getting LPG when you attempt to switch over, and that could be something as simple as a power supply problem such as a lead that’s come away from its connection.