ECU Remapping 101: Introduce More Power and Torque
Jake currently owns two N54 powered BMW’s – an E60 535i and E82 135i. Jake has 10 years of experience maintaining, repairing, and upgrading his BMW’s. The 135i features a single turbo Precision 6266 conversion capable of 700+whp; Jake completed the entire project on his own. With over 200 automotive articles published, Jake brings a balance of writing skill, hands-on BMW experience, and technical knowledge to the table.
Most engine and car performance upgrades begin (and often end) with an ECU tune or remap. This is considered a cost-effective method of gaining horsepower and torque. What’s more, the same procedure also helps to increase fuel economy.
The good news is that this is perfectly legal and only takes about half an hour to transform your car. Here’s everything you need to know about remapping.
What Exactly Is an ECU Remap?
An Engine Control Unit remap alters or replaces the software that controls the car’s ECU. This, in turn, is tasked to control various engine systems, such as the fueling and ignition or boost pressures in turbines. It also maintains the smooth functioning of other basic vehicle systems, such as the ABS or the air-conditioning, and more complex systems like adaptive suspension or the slew of independent safety tech.
Where performance is a concern, aftermarket parts for remapping help overcome stock manufacturer limitations that hinder available power. These are there for several reasons, with emissions regulations and longevity cited as the main hurdles.
How Is Engine Remapping Done?
An ECU remap involves connecting the OBD port (the same connection used to diagnose engine and car faults) to an external computer and first scanning the engine’s preset software or ‘maps’. After a complete scan, you can tweak individual parameters such as fuel injection pressure or ignition timing to your intentions.
If the vehicle was tuned or remapped operators can retrieve the original file and return the engine to stock settings. This, in effect, deletes previous remaps, something to consider if unsatisfied with work done elsewhere. Cars can then be tested on the road or put on a dyno and tweaked until the ECU reads values that best suit customers’ needs and wants.
What Are the Remapping Stages?
Engine remaps are done in 3 stages. The work carried out can vary among car makes and models, as well as the tuner doing the remap.
Stage 1 generally involves no parts mods but gets the most out of the vehicle with a simple software tune. And this is the most frequent and affordable type of remap.
All engines have some scope for additional power and torque straight out of the factory. This is one reason we see slight power and torque differences in the same car model for different markets. Rules, regulations, and standards are some of the main factors choking engines of their real potential.
With a remap, the low-down torque increases, meaning drivers don’t need to rev the engine as hard to produce the same power. This means lower consumption by default and the ability to lug the car in higher gears. It also helps with towing performance. How much extra bhp and torque is seen on the dyno depends on the stock engine.
Stage two usually means swapping out stock parts involved in airflow for something beefier. The first to go are the air intakes and catalytic converters and changes to the exhaust manifold and downpipes. Improving airflow is done with different exhaust configurations and layouts, depending on the type of engine. To get optimal performance once the changes are in, an ECU remap balances everything out.
During stage 3 more parts are swapped out. And in this stage things get serious. This builds on all done in previous stages and starts toying with cam timing, fuelling and boost pressures in turbos. Then there’s going for forged or billet internals, with pistons, conrods and cranks getting a makeover. And revisions to intercoolers, piping and turbines welcome drivers with a heap of untapped power low in the rev range.
Why Get an Engine Remap?
All newer cars can get engine remaps, even daily runabouts. There’s the increase in torque or pulling power, varying in different engines but ranging about 20 to 25 per cent in turbocharged petrol and diesel or 5 to 10 per cent in naturally aspirated cars. And this is available earlier on, so lower down in the rev range. You won’t be pushing the engine as hard. And this is a huge benefit when getting off the lights or towing.
The torque at a given engine speed or RPM is called horsepower. The more torque at higher revs the more the horsepower. This provides faster acceleration and is something required for safe overtaking. The way that power is delivered, or the engine’s powerband, is also improved to remove any dead spots for smoother operation.
Lower Fuel Consumption
Remapping the engine does not only benefit performance, but also fuel use. With more available pulling power lower down, the engine doesn’t need as much fuel to get going. This is one reason why engine remaps are popular with smaller displacement diesel cars and bigger V6 and V8 petrol cars.
Cost and Time-Effective
Getting a stage 1 remap will set you back a few hundred pounds. This is one of the cheaper, if not the cheapest ways, to upgrade performance. Stages 2 and 3 might be costly since additional parts are involved, but there are instances of doubling power without affecting longevity. Stage one is also quick, usually taking about 30 to 60 minutes.
You can order remote remaps or ones carefully calibrated by tuners online. This is something you can do on your own – good if you lack time to drive to the workshop.
ECU remapping has some cons. But these can usually be avoided. Being hard on the right foot and keeping the engine at higher revs longer will affect fuel consumption. But you get rewarded with more fun.
Also, insurance premiums may rise with significant increases in power. Another thing to look for is finding a good tuner. Changes that aren’t thought out carefully can have the opposite effect, with parts placed under more stress. This reduces reliability and can lead to engine damage.
Engine remaps are one of the most widespread vehicle modifications. They bring in more power higher up and more torque lower in the rev range, effectively improving acceleration times and top speeds.
All of this is helpful in different daily driving conditions. Owners get a more responsive vehicle, linear acceleration in all gears, lower fuel use, better towing ability, and can safely overtake without the engine hesitating.
Stage 1 tunes and remaps are affordable and can be done in under an hour (at home or the local garage), and revamp your love for a car you might have listed for sale. For performance cars, consider shelling out more in stage 2 and 3 remaps to get that competitive edge, either on the track or the street.