Recently, I came across the webpage of a tuning shop where the shop claims that by doing chip tuning they can simultaneously achieve superior performance and less fuel consumption (based on how they framed the description on their site).

Main question: is the above combination doable? They claim that this is possible because higher performance (torque) comes sooner (at lower RPM), so I don't have to whirl the engine that much. (Note: please, do not misunderstand me, I'm not saying they are fake or something, just want to understand whether this double effect is actually possible, and if so, how exactly.)

Additionally, they also say that one should expect the same engine lifetime (they are tweaking the ECU settings within the manufacturer's limits/suggestions). Opinion? (The condition of the engine is what I'd be worried about the most.)

I did take a look at the Wikipedia page here, however, it doesn't seem to say anything about simultaneous positive effects (still, the potential outcomes are combined with an "or" in the leading sentence).

A couple of additional, minor questions:

  • does chip tuning also imply modifications for the turbocharger, or only the engine itself?
  • could chip tuning result in a smaller number of transmissions (on the long term)?
  • could chip tuning mean that I may not have to switch gears (that often) on slopes?
  • if I end up visiting the place and asking them to upgrade the engine settings, can/should I ask for a copy (in any form) of the implemented changes (like a list of parameters they changed, either in digital/paper format)? Maybe it would come in handy in the future (e.g., if I want to revert the changes for any reason at another place).

Additional details:

  • the car in question is an Opel Astra (series J) with a turbocharged petrol engine (1.4L, 140 HP);
  • is a bit heavy and does not have a good performance on slopes (primarily, this is the reason why I'm considering this upgrade);
  • the performance gain "promised" by the shop is +20HP and +50Nm.
  • I think this question is too broad — too many topics — and needs more focus. I voted to close. Jan 7 at 18:16
  • I’m happy to reduce the number of questions, if that helps, and keep only the main one. Let me know whether that is acceptable and please consider keeping the question open.
    – mindthegap
    Jan 7 at 18:21
  • Thanks for paying attention! There's still five questions, and a lot of requests for discussion. Still, IMO, much too broad. We'll see if others agree. Know that you can edit your question using the "edit" button that appears below your question's text. Jan 7 at 18:24
  • Sure, thank you.
    – mindthegap
    Jan 7 at 18:25
  • There's no such thing as improving engine performance while decreasing fuel consumption. Power requires fuel. More power, more fuel consumed. Every hypermiler knows this, using the least power to lower fuel consumption. The most important consideration to tuning was mentioned - will this pass emissions inspection in your state (if required)? A 20hp gain means additional fuel needed. How much is anyone's guess but it will be more than what you're getting before tuning. A 14% gain in hp simply means anywhere from a little to moderate fuel consumption, depending on your right foot.
    – F Dryer
    Jan 9 at 3:40

2 Answers 2


In very general terms, across most mainstream manufacturers the tune out of the factory has to be conservative to cover a range of gas quality, altitude, weather conditions, driving styles, emissions regulations etc... plus to protect engine components from additional strain. Note that some changes will have an effect on the ingredients of exhaust gas, hence for emissions reasons California is now bans non-approved engine tunes.

It's no doubt possible for an aftermarket tune to advance spark plug timing for better combustion efficiency and output although many tuners also inject more fuel under load to control cylinder temps with higher timing. After that depending on the engine there's fuelling, turbo boost, VVT, EGR, DBW and many other parameters for them to tweak. One way that some basic commercial tuning solutions work is just to change the sensitivity of the accelerator pedal so that the throttle plate is opened earlier but would use more fuel depending on how the driver adapts to this change.

You could ask them exactly what they change but may get an approximate answer as much work on stock ECU's is done through time consuming reverse engineering so these details would be seen as a business advantage. However it all depends on how the many thousand lines of computer code, maps and variables are configured in the cars computers. Some similar model cars have different stock programming just depending on which model year or region is applicable. It's unlikely that the entire ECU is fully understood by anyone outside of the manufacturer and there are complex dynamics between the engine, transmission and other modules. With that said it's theoretically possible to modify one area of the computer but another area not to know of, or be ready for the change which could cause issues.

Bear in mind that pro tuning is usually done on a dyno with test runs between each change to measure torque and power at the wheels and to asses air fuel ratios, trims, knock, internal temperatures, amongst many other variables. An off the shelf after-market chip tune would be a standard recipe that doesn't account for mechanical differences between even identical looking cars. Goes without saying that trying to tune a car with poor maintenance or existing faults can cause issues. So sure there is risk in chip tuning, the chances are that if you can quantitatively measure before and after power, torque and MPG it wouldn't be as much as promised but could make an improvement.


It’s a fairly broad question so I’ll give a fairly broad answer: chip tuning, as the name suggests, means reprogramming the ECU and may or may not be done alongside other modifications. Typically an increase in performance will result in a loss somewhere - most likely engine life and fuel consumption. For an aftermarket tuner to add 20hp without compromising anything else they would need to know something that Opel don’t. That’s possible but unlikely. As with any vehicle, the design is settled upon by choosing the ‘sweet spot’ among a sea of compromises; the manufacturers know this and put a lot of effort into getting it right, since good ECU firmware adds nothing to the build cost but results in a better and thus more competitive end product.

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