Mazda Problems

You say the battery is okay, and it’s possible for it to show 12 volts on a multi-meter, yet still be ready to be replaced. The trick is to load test the battery. That is, measure the voltage across the terminals while the battery is trying to crank the engine. Sometimes, a battery that seems okay with no load will turn to jelly once you apply the starter-motor load.

Cars (and batteries) don’t like sitting around doing nothing. The car’s alarm and even things like the clock in the dashboard will all continue to run, slowly draining the battery. A drained battery, if sat long enough, will often not recover even if you try to recharge it. Beyond that, an auto electrician will be your best first stop.

This behaviour is probably a function of the way Mazda has calibrated the cruise control. In order for the car to initiate a downshift to regain some lost speed on a hill, it needs to recognise that it has, in fact, slowed down. But if it shifted down after losing just a single kilometre per hour, you’d find it would be constantly shifting gears in even slightly hilly terrain. And that would probably be even more annoying. The fact that it then overruns the set speed is probably the tall gearing (and physics) letting the car momentarily push through your 111km/h setting before it settles back to that speed.

But it’s worth keeping an eye on the speedometer even when using cruise-control, as this behaviour won’t work as an excuse during any roadside chats with the Highway Patrol.

A car like this shouldn’t frighten too many mechanics, largely because this is a fairly simple machine using well-understood technologies. In a situation like this one, most workshops will go back to first principles. That is: Air, fuel and spark.

On the surface, it sounds like a fuelling problem that is causing the engine to run out of fuel when it needs it most (when accelerating). So a check of the fuel filters, the fuel pump delivery pressure and volume and the injectors would be a good place to start. However, stumbling under load can also be caused by poor ignition, so the spark plugs, leads and coil(s) and charging system should also be checked out. Don’t forget things like a dirty air filter which also cause a case of the stumbles.

If all that checks out, then you need to start looking for a dud sensor somewhere in the engine bay. An electronic scan is a must for any electronically-injected car.

The smart money here suggests that there’s something your car’s electrical system and body computer don’t like about replacement LED lights. That’s assuming you’ve installed them correctly, of course. The first thing you should do is replace the standard globes and see if that restores the lights’ operation. If it does, you can be reasonably sure there’s a problem with the way the car reacts to the LED replacements.

Not all cars appreciate the conversion to LEDs. These newer lights draw a lot less current than conventional globes and, while that sounds like a good thing, the lack of current-draw detected by the body computer can cause problems. Another common problem with LEDs is that the low current-draw makes the car’s computer think that there’s a blown globe at which point it can trigger a warning light on the dashboard.

Proper maintenance is overlooked by many car owners, and it’s a real problem. Modern engines work very hard and have lots of intricate oilways and mechanical clearances that simply won’t tolerate dirty oil. On paper, the car you’re looking at hasn’t had clean oil or a filter change in 20,000km and that’s an awfully long time between drinks. In fact, it’s enough to perhaps give Mazda cause to void any new-car warranty remaining on it, should something mechanical go wrong.

Your best option would be to find another CX-5 with the options and in the colour you want, but with an up to date and complete service record. That’s the best way to prevent any major disasters down the track. The good news is the CX-5 was a popular model, so there should be lots to choose from.

That seems odd, but there might be a really simple explanation. I’d love to know whether you’re calculating your fuel consumption by working out how far each tank is taking you, or whether you’re relying on the trip computer in the car’s dashboard. If it’s the latter, the reason for your higher figure after a service could be very simple.

It could easily be that the mechanic test drives the car after each service to make sure everything is working as it should be. To do this, the tester is very likely to give the engine a couple (or more) acceleration runs with lots of throttle. It’s also possible the car is left to idle for a time for the engine to come up to temperature while the mechanic gets on with other things. Both these activities will lead to higher fuel consumption than you might experience in normal driving with no harsh acceleration or extended idling periods. Because the car’s trip-computer works out fuel consumption based on recent use, this treatment at the workshop will lead it to deliver a higher reading on the dashboard. That it happens only after a trip to the workshop is the big clue here.

To test this theory, drive the car normally for a week and see if the fuel consumption number drops. If so, you’ve solved the mystery. If not, you need to return the car to the workshop because something is not right and is causing the car to use more fuel.

A second-hand engine from a wreck is often a good an option, but only if you can find one that has been tested and comes with a warranty, otherwise you could be replacing your worn engine with an even more worn one. But with a diagnosis estimate of $5000 (and any actual repairs on top of that) I reckon a different workshop would be your best option. Frankly that seems (on the surface) a ridiculous figure and suggests that the workshop in question either doesn’t want your business or is assuming you’re a sucker.

Low oil pressure can be caused by various problems, and a good workshop should be able to check it out and give you a definitive answer on whether it could be fixed or the whole engine replaced. The good news is that the CX-5 is a popular model, so a replacement engine shouldn’t be too hard to track down.

Without knowing more, your problem could be caused by quite a few different things, including wheel bearings, driveshafts, brake rotors and even worn suspension components. But a really common cause of a vibration at a particular speed is a wheel that has shed one or more of its little balancing weights.

Given the parlous state of this nation’s roads at the moment, hitting a big pothole is a pretty good bet right now. And the shock of that impact is a typical way for the wheel to shed its balance weights. These small, lead weights are added to the wheel when a tyre shop fits new tyres. The idea is to use the lead to balance the wheel so it spins smoothly. Lose the weight and you suddenly have an out-of-balance wheel and tyre and a vibration is a likely consequence. A good tyre shop will be able to check this for you.

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.