Isuzu MU-X Problems

This is an annoying but relatively common problem in many cars, not just the Isuzu. Because a car’s air-conditioning system dehumidifies the air (as well as cooling it) the water that was suspended in the air has to go somewhere. When everything’s working properly, there’s a small drain-hose from the air-con unit, through the floor to under the car where the water can be dumped with no problems.

But what often happens is that the little tube or drain-hose becomes blocked. At which point, the air from the atmosphere has nowhere to go other than inside the cabin where it causes the mayhem you’re experiencing. By locating the drain-tube and cleaning it out, the problem should go away. If not, you need to look more closely at the car’s heater matrix which also lives under the dashboard and can leak coolant into the cabin for a similar range of problems.

Electrical failures like this are not uncommon even on brand-new cars. You could have a problem with the body computer, the wiring system, the lock actuators, a fuse or relay or even the key fob that you use to control the locking. However, the solution is pretty simple: This car should still be under the factory warranty (even if you’re not the original owner) so all you need do is take it back to an Isuzu dealer. Under Australian Consumer Law (provided you haven’t caused the problem through negligence or mis-use) the manufacturer is responsible for fixing problems like this one at no cost to you.

A lot of people think that a car that is switched off and locked won’t be draining its battery at all. But that’s not the case. Electronic equipment often imposes a constant drain on the car’s battery, and things like the stereo (for keeping stored radio frequencies) and any alarm system can create a constant draw on the battery. And when you think about it, even the remote central locking needs to be 'alive' all the time so that it can identify and act on your command to open the doors and prepare the car to be started.

However, I wouldn’t expect a nearly new car battery to be unable to survive a single week of not being driven. So maybe there’s something else going on. It could even be that the battery itself is faulty and not holding a charge as it should.

I’d be talking to the dealership as a fault with, say, a luggage area light staying on or any other piece of equipment not switching off when it should, is potentially a warranty claim. Just don’t expect Isuzu to cover the cost of a new battery. Like tyres and brake pads, batteries are considered consumables and are generally not covered by a new-car warranty. Although if it’s an electrical fault on the car that has caused the death of the battery, I reckon it’s an arguable case.

The last decade of dual-cab four-wheel-drive utes have emerged as the tow-vehicles of choice, and you see them everywhere filling roles exactly like the one you have planned. Popular models include the Ford Ranger you’ve nominated, Toyota HiLux, Mazda BT-50, VW Amarok, Mitsubishi Triton, Nissan Navara and Isuzu D-Max. But there are also cheaper alternatives including makes like the South-Korean made Ssangyong and various Chinese brands like LDV and Great Wall.

Just make sure you know exactly how much you need to tow before making a decision as some of the cheaper models don’t have the same outright towing capacity and even if they do, some of them don’t have the engine performance to make towing as easy as it should be. For parts availability, the Toyota would be king in really remote areas, but any of the major brands are pretty well covered in Australia.

Meantime, don’t rule out ute-based wagons such as the Ford Everest, Isuzu MU-X, Mitsubishi Pajero Sport and Toyota Fortuna. These offer better ride comfort when unladen thanks to more sophisticated rear suspensions and most have as much or almost as much towing capacity as their ute brethren.

It’s difficult to be definitive here without actually driving the vehicle, but there are at least two possible sources for this. The first is the simplest and involves either a wheel and tyre or driveshaft that is out of balance. That should be easy to diagnose and fix.

The second possibility is that the vehicle’s driveline (engine, gearbox and transfer-case) has what’s called a resonant frequency that, when reached at a particular speed range, will result in some weird harmonics and vibrations which is possibly what you’re feeling and hearing. This becomes worse when the torque converter locks up (to save fuel) and there’s no slip in the driveline to absorb these bad vibes. By shifting back to fifth gear, you’re raising the engine revs and moving it out of that harmonic patch.

I’ve heard that Isuzu has been remapping some ECUs (on-board computers) to try to move this harmonic zone into a different (higher) speed range (by manipulating the torque-converter lock-up point) where it won’t be a problem to most owners. The fact is the Isuzu diesel has never been the most refined one out there and some vibrations and harmonics are relatively common, However, they shouldn’t be bad enough to ruin your enjoyment of the car.

In the old days, a different exhaust was often enough to move the harmonics around or get rid of them altogether, but I can understand why that’s not really an option on a brand-new vehicle.

The car could be trying to trying to tell you that there’s something wrong with the key. So start with the basics. The most common cause for the key to not operate the ignition and security system (which is why the engine won’t start) is because the key’s battery has gone flat. Change it and see if that works. At the very least, try the second key (that should have come with the car) to see if it will operate things properly.

If not, then you have to start digging deeper, at which point the cause could be a glitch within the car’s body computer which is the brain that controls everything from the power windows to the central locking and immobiliser. If that’s the case, then an auto electrician is probably your best bet, but definitely check the key’s battery first.

Not being able to match a vehicle’s official fuel consumption number is not just common, it’s something just about every owner discovers the hard way. That’s because the test that determines the number is a laboratory test, not a real world one. The test figure serves as a comparison between different makes and models, not a realistic expectation of fuel consumption.

However, the additions you’ve made to your car will all increase fuel consumption. A nudge bar and tow bar both add wight and a set of roof bars can easily add a litre of fuel to every 100km travelled thanks to increased aerodynamic drag. Even the GVM upgrade might make a difference, especially if it sits the vehicle up higher, affecting aerodynamics even further. If you’ve also fitted bigger tyres, fuel consumption will rise even more. To be honest, I reckon 10 litres per 100km is about right for this vehicle and matches most other vehicles of this type. Don’t forget, either, that an Isuzu MU-X is a much bigger, heavier vehicle than a Subaru Forester.

A car that’s left to sit for a length of time will often develop a flat battery as things like the clock and security system slowly drain the battery. But this should not happen in just three days.

If there’s absolutely no drain on the battery (as checked by your electrician) then suspicion turns to the battery itself. It may have done this since it was brand-new, but the battery could have a manufacturing flaw or internal damage that means it won’t hold a charge beyond three days. Borrow a different battery and see if the problem goes away.

What you’re experiencing is the transmission calibration that many modern vehicles use to increase fuel economy. By always trying to be in a higher gear, the vehicle will record a better fuel economy number on the official test that compares it with its competitors.

The downside is that the constant upshifting means the vehicle will sometimes find itself in a gear that’s slightly too tall, and that’s when you’ll start to get the symptoms of feeling like the engine is labouring or lugging.

As you’ve noted, when the car shifts down a gear, the sensation goes away. The solution is to manually pull the car back a gear when this happens. If t really bothers you, you could ask Isuzu if there’s a software update that makes the transmission a little less eager to be in top gear.