Holden Commodore Engine Problems

It’s hard to say in absolute terms how accurate it is, but it is the most accurate indicator we have, given that the information comes directly from the injection system itself, and actually measures the fuel going into the engine. The claimed fuel consumption for the V6 VY Berlina was 6.6 on the highway and 11.00 around town, with an average of 8.2 L/100 km, which makes me think your car is about right.

It’s probably an ignition issue so start by checking the spark plugs and leads, and perhaps replace them if they haven’t been replaced in a while.

You need to have a diagnostic checker run over the engine to know if the oxygen sensor is playing up. Before you do anything drain the fuel from the tank, put fresh fuel in the car and take it for an extended run.

There have been thousands of Commodores converted to LPG without any problems, so there’s no reason why yours shouldn’t also run well on gas. Take it back to the installer; it’s his responsibility to get it running properly. If you don’t have success doing that contact the manufacturer of the system he’s fitted to your car and ask for their help in resolving the problem. If you didn’t want to go back to the installer find another one who works with the same system and go to them.

There are a number of things that could be causing the problem; you really need to get it to a mechanic the next time it happens. It could be the ignition coils, the crank angle sensor, the fuel pump or blocked injectors.

The Ecotec engine will be fine on LPG, many thousands have been converted. My preference would be for the injection system, it runs better, is more reliable, less prone to backfiring, and delivers the savings you want. But that said the older venturi/mixer system also works fine. Both Impco and Emer are respected brands. If you want to get more info on them talk to other owners who have had those systems installed.

Take it to a reputable mechanic and have them thoroughly check it, in particular they should check the crank angle sensor.

It's odd that there's such a disparity between steady-state highway driving and round town use. If the performance has dropped off I would be checking things like the exhaust backpressure, which might show up a blocked or partially blocked catalytic converter; if the performance hasn't altered look at the oxygen sensors.

Have a mechanic do a leak check on the head gasket to see if it isn’t leaking there.

From what we’ve been told there is no such thing as Dexron XI, so we’re not sure what oil has been used in your car. Dexron III is available and that’s the recommended oil, and Andrew at AW Automatics has told us that it’s still the oil to use.