Holden Commodore Problems

The answer is probably a pretty simple one in terms of what’s causing it. The warning light is to remind you to leave the car with Park engaged. So, the gear selector will have a tiny sensor or micro-switch that detects the selector in the Park position which is then conveyed to the car’s body computer. But if the sensor or switch is faulty or not adjusted correctly, the computer will think the car is not in Park and will light up the warning to alert you. The intermittent nature of the fault is what makes us think this is the case, combined with the fact that a quick flick of the T-bar button is enough to make the warning disappear.

So much for the cause, because the fix might be a bit more complicated. Depending on where the sensors and switches live, you may need to disassemble more of the car than would seem necessary to fix such a seemingly small problem. An auto electrician should be able to make sense of it.

A manifold leak will throw the engine’s fuel-air ratio out the window and can cause poor cold running and hard starting. The old school way of checking for a vacuum leak is to get the engine idling and then spray either carburettor cleaner (or something else flammable) around the intake area of the engine. If the engine suddenly picks up revs, you almost certainly have a vacuum leak. But be careful, spraying flammable stuff around a running engine comes with a fire risk.

The other thing to check would be the throttle body and the sensor attached to it that tells the computer how much throttle has been applied. Again, these can start to give false readings, throwing the fuel-air mixture out.

Before you do either of those things (replace the engine or the whole car) find out where the coolant is leaking from. You might find that it’s a simple case of a leaking hose or a worn out water pump that is causing the leak. If that’s the case, it could be fixed for a few hundred dollars or perhaps even less. Even if the problem is a rotted welch plug or a blown head gasket, the cost to fix it won’t be anywhere near as high as replacing the engine.

On top of that, you know the history of the engine you have, while a second-hand engine can be a bit of a lucky-dip: You might get a good one, you might not.

All the V6 Commodores from this era used much the same automatic transmission, a four-speed unit. While most of these units were identical, there were some detail differences across the years, so make sure you get the transmission with the correct number of electrical pins to be compatible with the wiring loom in your car.

It shouldn’t matter whether the replacement transmission came from a car with a floor-shift; it should still hook up to your column shift mechanism with no problems. You might have to swap a few bits and pieces involved in the shifter mechanism to mate it all, but you’ll be able to make it work.

This could be the result of a worn or poorly adjusted transmission, a worn torque converter or even something simple like a low transmission-fluid level. So that’s job one: Check the level of fluid on the dipstick. If that’s okay, you really need to see a transmission specialist who has probably seen these exact symptoms before. What I can tell you for sure is that the automatic gearboxes fitted to Holdens of this era did have a finite lifespan before they needed either an overhaul or outright replacement.

But make sure your mechanic checks that the cause of the vibration is not a worn universal joint or bent axle or an out-of-balance drive-shaft. Even a sticking brake or a worn engine mount can induce vibrations into a moving or accelerating car, so rule all that stuff out first.

First thoughts would be that you have a fuel injector that is not spraying either the correct amount of fuel and/or in the correct pattern for proper combustion. This will certainly bring on the symptoms you’re seeing, as well as ruining fuel economy. It’s also most likely to show up if the engine has been sitting for a while.

But the reality is that a modern engine like this one has literally hundreds of electronic sensors and systems that can all add up to poor running and economy. The best bet is to have the car scanned to see if the on-board computer has logged any faults. Without this intelligence, you’re flying blind, replacing parts that may or may not fix the problem.

There are literally hundreds of things that can cause a check-engine light in a modern, computer-controlled car. A problem with the ignition, fuel system, emissions-control system, air-intake, lubrication, cooling and much, much more can cause this light to illuminate.

The best way to proceed is to have the vehicle electronically scanned. That way, the computer can tell the mechanic where the problem is and, hopefully, precisely what’s causing the check-engine light to flicker on.

For the record, however, a common fault with the V6 engine in this series of Commodores is a stretched timing chain that the computer interprets as incorrect valve timing (which it is). Plenty of owners of this model have discovered this as the cause of their check-engine light.

The first thing to do is make sure your battery is earthed properly and all the relevant electrical contacts are tight and clean. Low voltage or a poor connection can easily cause the problems you're seeing, especially if they've all occurred more or less at the same time.

The next thing is to have the vehicle electronically scanned. That will tell you what faults the on-board computer has spotted, and you can then tackle them logically instead of replacing parts that don't fix the actual problem. The rough running could be anything from a dud oxygen sensor to a fuel-injection problem and lots in between.

I would suspect the heating and air-conditioning problems are separate to the engine's poor running, but anything's possible when a car's electronics start playing up.

It's good news. Your car is indeed compatible with E10 fuel which means you can use the slightly cheaper fuel without risking damage to your vehicle. The car should also run exactly the same as it does on normal unleaded petrol, although you may find you use slightly more fuel per 100km. This should, however, be more than offset by the savings you'll make at the pump.

Both those models of Holden used the same engine; the L36 (Holden's internal code) Ecotec V6. As such, you should be able to fit the engine from the VT Commodore into the Statesman with very few other changes. The biggest hurdle will be if the Commodore donor car was a manual-transmission vehicle, as the ECU may be different to the Statesman's unit to allow for control of the electronic transmission. The best bet is to retain the Statesman's wiring and computer and change over only the engine hardware from the Commodore.

The other (minor) catch is that the VT's version of the V6 was tuned for 147kW, while the later version of the same engine in the Statesman was good for 152kW. There was a small torque difference, too (304Nm plays 305Nm). So you'll be trading off a small amount of performance but, realistically, not enough to notice.