Engine Mapping Pros and Cons

Engine Mapping

What is Engine Mapping?

You might be tempted to pimp your ride by engine mapping the onboard computer. But is it worth it?

All modern cars are controlled by computers. These are set up with algorithms which calculate the optimum average responses for each part of the vehicle using engine mapping.

The onboard computer detects certain driving conditions and then optimises the way different parts of your car function accordingly. Manufacturers programme the car’s computer to automatically adjust things like:

  • The amount of fuel supplied to the engine
  • Increase or decrease the boost pressure of the turbo
  • The air intake
  • The way the exhaust functions

For example, the car’s computer can detect when you are going up hill towing extra weight, say a caravan, and optimise the car’s resources accordingly to give you more pulling power.

Default and Driver Selected Engine Mapping Settings

My current car has 32 separate engine mapping processes and 6 driver settings including economic, comfort, dynamic and sporty to select depending on the mood! These are prebuilt mapping settings. Some, but not all, modern cars have these driver selection options.

Here’s what some of the processes do:

  • 4 processes monitor emissions and tunes the engine accordingly and alters the amount of fuel and air. Load, acceleration, speed, even the altitude
  • 4 adjust the steering, suspension and handling
  • 4 control the heating, ventilation and aircon
  • 2 control the exhaust systems
  • 2 monitor the air mass meter (the air intake)

Other processes cover the braking and antilock systems, vehicle security and locking mechanisms, miles per gallon, fuel range, and everything else besides. As you’re probably gathering, the way these processes work together is pretty crucial to having the vehicle function efficiently!

Good Engine Remaps and Bad Engine Remaps

The manufacturer includes a compromise or average setting for each engine mapping process as it comes out of the factory. These settings can be altered at a reputable garage to make your car run to your own specifications. This includes making the vehicle faster and more sporty.

This is not to be undertaken lightly! All the processes still need to work in harmony to ensure your car continues to function efficiently. For example, we have seen a vehicle in the workshop which has had an engine burnout which made a hole the piston because the process to control the fuel injection had been mapped to over supply fuel, causing excess heat in the engine thus causing mechanical failure to the piston in the form of hole. Unfortunately, this is not a cheap fix so it’s important to choose your garage carefully if you’re planning to have your engine’s computer remapped.

Another example of a bad remap we’ve seen is a car which had been mapped to make it accelerate faster (traffic light derby winner!). This vehicle was again, over-fuelling which created more carbon which in turn blocked EGR (Exhaust Gas Recirculation) valve. This caused the car to produce excessive smoke from the exhaust every time the vehicle accelerated and needed replacing. Less expensive than a piston, but still an unnecessary expense and all down to bad engine mapping.

The Engine Mapping Moral

Manufacturers spend millions working out the best average driving responses from their engine mappings. Therefore, a thorough and well thought out engine remap is not going to be a quick and easy cheap job, and it will certainly cost you a few hundred GBP.

As with anything in life, you get what you pay for so beware of a cheap remap. This may well cost you much more down the line if there is a mechanical failure.

We don’t offer engine remapping at VFR Motors, largely due to the complexity and because we’ve seen so many vehicle failures lately due to badly remapped engines. If you’ve had your engine remapped and you think it’s been done poorly then it may be worth getting it reset.

If you’re finding your car has issues after a remap and needs to be looked at, you can get in touch via the contact form or give us a call on either of these numbers: 0116 3190 118 or mobile 07850 881 911.

Here’s our our Leicester garage on Google Maps if you don’t already know where we are.

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