Pros and cons
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of remaps
Are you ever tempted to remap your engine in search of better fuel economy and improved performance? If you are, read on
Words: David Wilcox Paul Busby, chief executive of Viezu Technologies, describes his company as a responsible tuner. Working in a sector that is usually linked to non-manufacturer-endorsed performance hikes, Viezu is different. A substantial part of its business is with leets seeking more mpg rather than more mph. Last year the company won two local Chamber of Commerce awards for innovation through technology and in February this year it was awarded ISO9001 accreditation for quality management systems.
Viezu’s stock-in-trade is remapping engine electronic control units (ECUs) to improve performance and/or fuel economy. With just 13 employees, Bromsgrove, Worcestershire-based Viezu is, nevertheless, a big player in its ield, carrying out 600 to 800 remaps each month. Customers take their vehicles to any of Viezu’s 375 dealers in 34 countries; the dealer copies the engine map data ile and emails it to Viezu’s technicians in Bromsgrove. They modify it according to the customer’s wishes and return it – within one hour – to the dealer who uploads it to the vehicle, overwriting the standard ile.
Why would vehicle manufacturers with multi-million pound R&D budgets write engine maps that leave scope for improvement? The view often expressed is that, in a nutshell, manufacturers leave slack in their maps to ensure that vehicles can work in any market where climate, fuel quality and maintenance regimes might conspire against them. Viezu claims it taps into that margin, merely uncovering hidden points on the standard maps, and remaining within the engine’s tolerances. Manufacturers do this when they offer higher power ratings or economy-oriented models, says Viezu, but aftermarket remapping costs less.
Fewer than 5% of Viezu’s remaps are for heavy trucks (although it is big business for Viezu’s Turkish dealer) but 40% are for vans, with Busby explaining that an increasing number of van and car leet managers are asking for improved mpg. The essence of Viezu’s economy-orientated remapping is boosting torque at low engine speeds. By modifying the curves, Viezu changes the engine’s response to data coming from its sensors, adjusting the air-fuel ratio, injection pressures and timing, boost pressure etc, thus delivering improved fuel eficiency. It also smooths the curves, removing minor irregularities, but still following their general shape, albeit just a little higher. Busby contrasts this with rival remapping companies that provide a power spike in search of a startling performance hike. “That is not what we are about,” he emphasises.
Speed-limiting
Economy remaps may be supplemented by top-speed limiting and engine-speed limiting. This work – remapping and speed-limiting – costs around £400 for a single vehicle and £250 to £350 per vehicle for a leet operator submitting multiple vehicles. Busby says the iles are modiied individually to achieve what vehicle owners request. “The majority of tuners have a library of iles,” says Busby. “We don’t operate like that. It’s very much based on an intelligent conversation about what you now want your vehicle to do.” Viezu claims its fuel-saving remaps increase fuel economy by 8% to 12%. “If we add speed-limiting, 15% is far more typical,” says Busby. Viezu refers to a major leet operator that “saw an 11.2% improvement in fuel economy and a reduction in carbon emissions of 30%” during track trials at Millbrook. Now, it is
indisputable science that CO2 emissions are
geared on a 1:1 ratio to fuel burnt, so CM asks Busby to clear the confusion. He explains that by ‘carbon reduction’, he is referring to a lower exhaust
smoke opacity reading. If its fuel economy claims are accurate, Viezu can rightfully claim to be reducing CO2 emissions by a similar margin.
CM asks Busby what happens to key regulated pollutants such as particulates and oxides of nitrogen (NOx). Viezu has never commissioned thorough emissions testing on a recognised drive cycle as performed in Millbrook’s variable temperature emissions chamber and thus Busby is unable to comment.
Busby says smoke opacity is the only emissions check in the MoT test for diesel-engined vehicles, so that is Viezu’s only measure. “We are responding to demand for better fuel economy,” he says, adding that the word ‘emissions’ never crops up in those intelligent conversations with customers. “Even leet managers never talk about emissions. Their mission is to save fuel.” Busby says much of Viezu’s leet work is covered by non-disclosure agreements and he is unable to provide formal leet testimonials.
The World Health Organisation recently conirmed that diesel exhaust is carcinogenic to humans: it is particulates that are doing the damage. Thus we ask Busby why Viezu is willing to remove diesel particulate ilters (DPF) from exhaust systems. He says DPF removal is “something we question internally, asking ourselves should we do it?” The answer, so far, is yes. “There is very strong demand for it,” he says, mentioning motorists whose cars’ DPFs are clogging because they fail to reach the operating temperature needed to regenerate them. “It is not unusual for customers to be on their fourth DPF in under 30,000 miles. Something has to be done,” says Busby. “We get asked to reduce AdBlue, but it’s something we don’t do, even though there is huge demand,” continues Busby. “Fleet customers are desperate to get this done and there are tuning companies that will do it.” Although Viezu declines to turn down AdBlue dosage in NOx-reduction SCR systems, its remapping is almost certainly having a similar effect. Remapping to improve performance and fuel consumption suggests combustion temperatures are higher, producing fewer particulates. The inevitable consequence is more NOx, linked to the formation of acid rain, respiratory problems and climate change.
The manufacturers’ view
What some claim is ‘slack’ in the engine maps for different market conditions is in fact performance and economy balanced with the need to control emissions. While vehicle makers comply with stringent emission limits to meet type approval, remappers are up against nothing tougher than an MoT smoke test. Remapping thrives in the gap between tough type approval emissions standards and weak in-service emission tests.
So what do vehicle manufacturers think about aftermarket remapping, even that aimed at improving fuel economy? CM asked Mercedes-Benz and Iveco, both big players, who gave short shrift to the idea that aftermarket remapping is a harmless way of taking advantage of the slack in their engine maps. “That’s nonsense,” says Nick Blake, sales engineering manager for CVs at MercedesBenz UK. “Vehicle manufacturers walk a tightrope, balancing engine performance and economy with emissions. We spend a phenomenal amount of money on emissions work. Companies doing remapping have no idea about regulated emissions.
“I feel very strongly about what’s going on. My understanding is that to modify a vehicle in such a way may cause its emissions to exceed the legal limits that applied when it was new [Road Vehicles (Construction and Use) (Amendment) (No3) Regulations 2000 – Regulation 61A (3)]. There is no doubt that remapping changes the emissions. If you are getting more power and torque, it’s almost certain that the injection timing has been advanced and combustion temperatures are higher. That in itself will increase NOx emissions. It also effect engine cooling, raising piston and valve temperatures.
“Any margin we leave in a map is there to make sure that the engine continues to perform within the legal emissions limits, even when there is wear in the injectors.
“I have no problem with engine remapping per se providing it meets the same rules as when the vehicle was built.” Blake adds that vans and trucks that go into franchised dealers for maintenance might have their ECU (engine control unit) ‘relashed’ to upload the latest software ixes or improvements. “This will overwrite the remapping, putting it back to the manufacturer’s speciications.” Martin Flach, product director at Iveco UK, is equally scathing, rejecting the notion that aftermarket remappers are simply doing what vehicle manufacturers do when they offer higher power ratings, but charging far less for increasing output or improving fuel economy. “If we offer several power ratings, it’s fairly rare the engine mapping is the only thing that changes on the more powerful versions,” says Flach. “They may have a different turbocharger, there will be piston-cooling jets on the oil circuit, which you don’t have on the lower power ones, and we put in different valve seats.” As far as remapping for fuel economy is concerned, Flach outlines how Iveco created the EcoStralis, the economyoriented version of the Stralis unit. “Yes, we remapped the engine, but that was a very small part. The real gains came from working on the gear-shifting logic, dropping the speed-limiter setting to 85km/h, using a taller rear-axle ratio, improving the aerodynamics and putting on Michelin SaverGreen tyres. That lot gave us a 7% fuel saving.” Is it possible that remapping alone could achieve 10% better economy and yet keep emissions within the type approval limits?
“Not credible,” says Flach. He suggests remappers should have to go through precisely the same type approval emissions testing procedures as vehicle manufacturers.
We passed these manufacturers’ views on to Viezu. Busby comments: “Responsible remapping undoubtedly has an important role to play in improving leet economy, and it genuinely is possible to achieve some signiicant gains without any detrimental effect on emissions. Proven techniques such as electronic speed, throttle or rev-limiting, which are requested by many leet customers, simply encourage and ensure drivers only operate the vehicle within its optimum range. This type of approach does not provide any additional access to the maps already developed by the manufacturers and consequently does not affect emissions output in any way.” ■