Why are ECU / Engine Remaps and Tuning Boxes so Effective?

by Andy Published on Thursday, April 30th, 2015

When one purchases a vehicle, they likely expect engine ECUs to be optimally mapped prior to sale. While they are typically very well mapped, it is subjective whether or not it is done optimally.

In this article, I will look at engine/ECU remapping and chipping and the use of tuning boxes. I will explain why remapping works and, in most cases, why it is safe.

With most manufacturing, compromises have to be made. ECU maps are no different. Yes, manufacturers invest a great deal of time in engine tuning and testing in the harshest climates. However, tuning criteria are designed around extremes that do not necessarily fit the requirements of the average customer or where the vehicle will be used.

Manufacturers must adhere to and comply with various legislative constraints surrounding emissions and other parameters set by the different governing bodies. As a result, this may affect the quality of factory ECU maps regarding available performance and/or MPG.

Many manufacturers produce vehicles in their range that, to some degree, compete with each other and, in some cases, even share the same engine. For example, a VW Golf may share the same engine as a VW Polo or a Porsche Boxter competing with the Porsche 911. The point is that it would be marketing suicide for a Porsche 911 to be considered slower than its younger brother. As a result, some engines are intentionally detuned or, let’s say, not tuned to their full potential.

Furthermore, manufacturers are obligated to tune vehicles for wildly varying conditions, i.e., -40 to +130 degrees or very high altitudes where the air is much thinner. This is one of the reasons why engines run rich from the factory. It accommodates dramatic climatic conditions that the average driver will never see. Even with the latest technology in fuel and ignition control, compromises on engine tune still have to be made just in case the vehicle is used in such conditions.

Vehicles need to survive the factory warranty period without fault. For example, it’s not uncommon to find an engine that is detuned for torque output to ensure that the drivetrain doesn’t fail. This begs the question: Why would anyone want to remap/chip their vehicle if there is an increased risk of a component failure?

Well, here is the point I am trying to make here. Car manufacturers must tune vehicles to cater to mechanically unsympathetic customers! This is very important. Drivetrains or engines (as an example) can fail when they are abused or raced from cold. It is this type of customer and not your average enthusiast that manufacturers are trying to protect themselves against, at least within the factory warranty period.

Furthermore, fuel quality is not guaranteed. Customers embracing remaps are more inclined to use higher-quality branded fuels and/or fuel conditioners, unlike the average user. Manufacturers have little control over this, so engines are tuned accordingly and with a little to spare regarding turbo pressure, air/fuel ratio, ignition timing, etc.

A combination of the above is why we see so many forced induction engines running rich from the factory. This and all of the above give reputable tuners the opportunity to liberate additional performance safely and improve MPG from engines under certain conditions.

If in doubt, stick with reputable tuners and tuning box manufacturers, as this helps ensure you receive a well-developed tune.

Also, bear in mind that even though normally aspirated engines can be remapped, the gains are minimal when compared to forced induction engines. It would also be prudent to notify your car insurance provider.

UPDATE: We were asked how ECU remaps, or Tuning Boxes can improve MPG?

With naturally aspirated petrol engines, mpg gains are marginal at best. Minor adjustments can be made to ignition timing and air/fuel ratios, but both power and mpg gains are minimal. This is the case with virtually all non-forced induction engines.

With turbo or supercharged petrol engines, power gains are usually very good with tangible but small MPG gains. MPG gains are two-fold on forced induction petrol engines. Many turbocharged engines run very rich from the factory under acceleration (open loop lambda). By carefully leaning out the air/fuel mixture under open loop conditions, fuel consumption can be reduced. This is more difficult with more modern engines that utilise wideband lambda technology. That said, most gains (if any) are achieved by improving the spread of torque across the rev range or, in particular, lowering it. If more torque is available lower in the rev range, less throttle is required to achieve the same level of accelerative effort. Of course, more fuel may be required to achieve the additional torque but lowering engine RPM more than compensates for this. And this is where diesel engines excel…

Turbo diesel engines – excellent power (torque) gains and potential mpg gains. Most mpg gains are achieved in turbo diesel engines by using the principle described above – making more torque available lower in the rev range. If you used to use 40% throttle but now only have to use 35% throttle to achieve the same accelerative effort, then you will most likely save fuel once the novelty of the extra power has worn off!

I hope that helps.

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10 thoughts on “Why are ECU / Engine Remaps and Tuning Boxes so Effective?”

Tim says:

September 28, 2017 at 10:02 am

Ok so I’d like to know how changing the physical/measured values affect the predicted states of the engine i.e what is the impact on a Gaussian process regression control strategy as used in many current production vehicles? Would the expected vs the monitored not produce constant implausible values therefore raising error flags?

Reply
1. Andy says:
  
  October 1, 2017 at 11:39 am
  
  Your question is too generic. Most remaps retain the built-in control and safety parameters and will, therefore, still operate within the set parameters. For the benefit of the readers, one example would be increasing the torque limit and another, raising the engine knock limit. The first example is common practice and the second a foolish compensation for poor quality tuning. It is acceptable to tune “around” control points that would raise error flags but the tuner must know what they are doing.
  
  Reply
Frot says:

July 10, 2017 at 4:56 am

Good day Andy
I’m an off-road enthusiast but I also like to look after my vehicle, I service it regularly and hope to get many years use out of it. Not surprisingly, the more one reads on this subject the more one wonders where the truth lies.
I would like to remap my Toyota Hilux turbo diesel in the hope of better torque and power for off-road driving. The guy who has just run a diagnostics check on my engine fuel system owns the same type of vehicle and would not commit when I asked whether he thought a tune/remap would compromise the reliability of the engine. (He has not remapped his engine but could easily do so given his expertise and contacts).
Here is an extract from an article from what I would consider to be a fairly reputable website:
One of our mates chipped his diesel manual to give him more flexibility and economy when towing, letting the vehicle run in top gear, rather than needing a downshift on hills. There are at least four downsides to this procedure. Firstly, the engine is operating at lower than designed revs for the torque/power figures it’s producing and that loads the pistons, rods and bearings with forces that were never forseen by the engine designer; secondly, combustion pressure and heat rise (check your pyrometer if you don’t believe us); thirdly, loads on the overdrive gears in the box are also outside design expectations and, fourthly, water and oil pump (and mechanical fan) speeds are lower.
Another concern I have is that some Hilux owners have reported cracked pistons. How does one deduce whether that was caused by faulty injectors, lack of servicing, bad engineering/design or maybe………………an engine tune or remap.
I don’t dispute anything you have written, I wish only to make the point that it is never an easy decision based on all the articles on the subject.

Reply
1. Andy says:
  
  July 10, 2017 at 12:39 pm
  
  Hi, common sense will conclude that any engine tuning that increase torque/HP will increase wear and the probability of failure. However, the question is if the additional wear will be noticed or in any way significant within the usable life of the vehicle. Save for aggressive tunes such as stage 2 and above the answer is generally no due to over engineering normally factored into manufacturing to help accommodate the less sympathetic of owners. That said it is by no means unreasonable to expect exceptions to this rule and the Hilux may very well be one of those exceptions.
  
  How the vehicle is treated and used is key which is why we hear of low mileage, standard vehicles failing and tuned, higher mileage vehicles of the same model continue on without fault. Also, a remap plus towing can take its toll.
  
  I don’t have any particular experience on that vehicle to comment further but I would certainly heed the advice of existing owners and tuners of those vehicles to understand the actual weaknesses to determine if the risks are genuine.
  
  Reply
Driver says:

May 1, 2015 at 5:53 pm

Sorry, Im not having this remap tosh. Most cars are specifically ordered nowadays. They know the customer’s location or at least where the car will be bought. They even know which country the car is being delivered to.

So, its absolute tosh that a car built for the British market is going to be mapped to take account of temperature variations from -40 to +130 degrees! Neither will the british intended car be mapped for driving at 8000 feet or above sea level.

To suggest car manufacturers are not able to take account of the cars intended market location is utter naivety.

Reply
1. Andy Archer says:
  
  May 4, 2015 at 11:35 am
  
  It is difficult to take your response seriously because I can’t tell if you are serious or just trolling?
  
  Yes, there are mapping differences between continents, mainly due to fuel variations more than anything. However, if you genuinely believe that UK delivered cars are only mapped for the UK then you are either incredibly ignorant or just looking to attack me for whatever reason?
  
  You may or may not have noticed that we form part of the EU? Car manufacturers share a long list of regulatory constraints relating to engine emissions, vehicle safety etc. Therefore, any UK vehicle must operate efficiently AND safely in other EU member states. An EU manufactured car needs to operate in the south of Spain in the warmest season as well as the north of Finland in the coldest season.
  
  Similarly, most vehicles destined for the US market will be mapped to work in Florida (or even South American countries) AS WELL AS the coldest parts of Canada. Engine sensors that monitor air flow, air density and temperature go a long way to facilitate real-time mapping adjustments but much more safety is actually written into standard mapping. Speak to any engine tuner – the evidence is irrefutable. We have standard turbocharged cars turn up with black exhausts and deposits all around the rear bumper because they run VERY rich due to some of the aforementioned constraints outlined in the article.
  
  On a final note, this article isn’t an opinion. It is based on actual experience and information supplied by manufactures themselves.
  
  Reply
  1. DJF says:
    
    May 6, 2015 at 9:50 am
    
    An interesting post on ECU remaps.
    I purchased a Skoda Octavia 1.4 TSI DSG 4 weeks ago and live in Lanzarote.
    As you have stated the engine would be optimised for the EU, Finland to the Mediterranean Spanish coast.
    Of course, we are further south than that, off the coast of Africa.
    I am thinking that because we do not go below 12*c and could rise to 45*c a remap would be advantages.
    In your experience would the local VAG service centre on the island carry out the remap if requested or would it invalidate the warranty?
    
    Any advise will be gratefully received,
    
    David
    
    Reply
    1. Andy Archer says:
      
      May 6, 2015 at 10:06 am
      
      Hi David, I would recommend finding a reputable VAG tuner in your country and carefully discussing your requirements with them. Where and how the vehicle would be used, fuel you will likely be using, if you are looking for additional power and/or mpg gains etc?
      
      Reply
      1. David says:
        
        May 8, 2015 at 11:13 pm
        
        Thanks Andy, not sure there will be a dearth of VAG tuners on the island, hence the reason to ask if in your experience the local VAG service centre would take on the task without invalidating the warranty.
        I suppose it won’t do any harm to ask them and they might know of an independent tuner who they can recommend,
        
        Cheers
      2. Andy Archer says:
        
        May 11, 2015 at 8:16 am
        
        Hi, I think it is unlikely but they may be more flexible than over here.

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