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A bad tune can hurt more than just your wallet

You don’t need to look too far back to realise diesel performance tuning in Australia has had a dramatic change. Even in the last 5 years it’s gone from a niche modification off-roaders make to something every man and his dual cab ute wants for family work, the 9-5 grind, and serious outback travel. After all, it’s one of those modifications with no negatives, if it’s done right. That last point is the key, and something we’ve come across more than a few times here at Roo HQ. There’s more tuners than ever, many of them are good, many more aren’t.

There’s a few reasons behind this too. The most obvious is with the Commodore and Falcon dying out more and more people are flocking to dual cab utes, the other is that with the birth of electronically controlled diesels it’s never been easier to tune a diesel, but those same tools that make it a simple process also make it simple to stuff up. Any old numpty can download a tune off the internet, throw your pride and joy on a 2nd hand dyno and call it good. The problem is, with dodgy tuners paying for the work isn’t where the credit card swiping ends, in many cases you’ll be paying for it for years in excessive fuel consumption and replacing components way before their use-by-date, and in most cases the tuner won’t have a clue why. Sound complicated? Well it is, and it isn’t, but that’s why we’re here today.

Excessive soot might make for great photos, but it can lead to costly damage


When it comes to chasing power out of your 4WD the actual figures are essentially irrelevant, with just about every other consideration coming in to play before them. We’ll look at what potential limitations the vehicle has like torque limiters, substandard injectors, and turbochargers only just up to the task and then work in those parameters with the end goal for usable power at the speeds you need them. If at the end of the process the numbers are large, that’s fantastic, but we really couldn’t care less. For some tuners those numbers are the one and only goal. They’ll throw driveability to the wind giving you a 4WD that potentially runs hot, damages components, and feels everywhere you’re driving it, except flat stick on the dyno. Rather than chasing efficiencies in little places here and there these tunes are often the 4WD equivalent of a sledge hammer. Throwing boost and fuel into your engine with no regard for anything else, as long as it doesn’t go bang while they have the keys.

A DPF failure from poor tuning can see you out of pocket thousands of dollars



So what does all this mean apart from slightly higher fuel consumption making all that power? The big factor is your 4WDs Diesel Particulate Filter (DPF), a vital piece of emissions equipment designed to reduce harmful diesel particulates from entering the atmosphere. It works like a giant sponge with a couple of sensors inside. As your engine runs, the DPF simply captures the particulates, eventually choking up and letting the ECU know it’s time to do a burn, or regeneration cycle. To achieve this the engine will dump huge amounts of fuel into the engine, raising exhaust gas temperatures through the roof literally burning the build-up into finer, less harmful particles.

Now when these dodgy tuners start throwing around keyboards like they know which end of an exhaust to put the engine on they’ll often do what we call a dirty tune. A performance tune that basically dumps fuel into the engine for maximum power. It’s an incredibly basic setup with little thought put into creating usable power. It was a very common way to tune a diesel engine when we were still spinning spanners on mechanical injection pumps and even many performance chips, but it doesn’t cut the mustard now engines and our tuning methods have advanced. Y’see, the big problem isn’t necessarily jamming fuel into the engine, it’s excessive diesel soot finding its way into your DPF, sometimes up to twice the amount. That means the DPF is filling twice as fast, requiring twice the burn cycles, and twice the fuel used to do the burn as a result. When you consider that some models can suck in an extra 3L to do the burn, and are doing them every few hundred kays it starts seriously adding up over the life of the vehicle, even if your instant fuel usage looks great. Not only this, but most DPFs will also have a limited service life. Over time the ceramic material inside can become brittle, breaking down and clogging the filter requiring a full replacement. Twice the soot going through, half the DPFs life. When you budget in a replacement DPF from Toyota for an N80 HiLux right now will run you $4,000 it’s something you probably want to keep in working order.

You won’t find much overlap between usable power and a dyno queen


In Facebook land where facts don’t matter and the info is made up anyway the solution is often seen as simply removing the DPF. The logic is basic enough, no DPF, no regeneration cycle using fuel, no filter to clog up and require replacing. The problem is it’s kind of like yanking your exhaust off because you bought an eBay mild steel special and it rusted away, rather than a quality stainless jobby. Making bad decisions to cover bad decisions rarely leads to good results.

When it comes to removing emissions gear the Environmental Protection Agency takes things pretty bloody seriously too, to the tune of a $250,000 fine for the vehicle owner, and $1,000,000 to the workshop doing the work if they want to throw their weight around. That eBay DPF delete pipe isn’t looking too crash hot now is it?

Like it or not, high-tech 4WDs are the way of the future. If you like things like capability, good fuel consumption, and being able to breathe when someone starts the engine it’s a damn good thing too. Sooner or later every diesel workshop will either be forced to get with the times and start working with technology, or they can keep bringing a knife to a gun fight till they find themselves not having a clue how to work on a new 4WD, we’re just ahead of the curve like usual. By setting your vehicle up to comply and work within the factory systems you’re often not only working within the factory warranties, you’re saving yourself from the potential risk of life-changing fines, decreased air quality, and a whole lot of negative side effects in your 4WD. When things are done right, they just work better, and that’s something you can’t download off the internet.


Contact us now or call 1300 305 709 (Mon-Fri) and let us show you what we can do for your 4WD or contact one of our 60 nationwide dealers directly.