BMW's 2.0-litre engines are some of the most popular cars we tune at our Hertfordshire workshop. The 20d diesel and 20i petrol are fitted to a huge range of models, from the 1 Series to the X3, and both respond very well to a Stage 1 remap. This guide covers what a BMW remap does on these engines, typical gains, and what to expect on the day.
What does a BMW remap do?
Every BMW engine is controlled by an ECU (BMW calls it the DME or DDE) running software set at the factory. BMW sets boost, fuelling, timing and torque limits conservatively so one calibration suits every market and fuel. A remap adjusts that software to make better use of the engine you already have.
A Stage 1 remap is software only, on a standard car. Mac Tuning has developed its own software for most vehicles over years of testing and research, and every tune is custom-tweaked for the specific car in front of us rather than being a generic file. For more on how it works, read our guide to a Stage 1 remap in Hertfordshire.
BMW 20d remap (B47 diesel)
The B47 2.0 diesel is used in the 120d, 220d, 320d, 420d, 520d, X1 20d and X3 20d from around 2015 onwards. Most versions make about 190bhp and 400Nm as standard.
Typical Stage 1 gains (typical, varies by car): around 225–240bhp and 460–500Nm.
On a 20d the extra torque is what you notice most. The car pulls harder from low revs, overtakes take less effort, and it copes better with a full load or a trailer. Earlier cars use the N47 2.0 diesel, which also responds well; we'll confirm the figures for your car.
BMW 20i remap (B48 petrol)
The B48 2.0 turbo petrol comes in several outputs. The most common are the 184bhp version in the 120i, 320i, 420i and 520i, and the 258bhp version in the 330i, 430i and 530i (labelled 30i, but the same 2.0-litre B48 engine).
Typical Stage 1 gains (typical, varies by car):
184bhp 20i (120i, 320i, 520i): around 250–270bhp and 400–420Nm
258bhp 30i (330i, 430i, 530i): around 300–310bhp and 450–470Nm
The B48 is a strong engine with good headroom. Petrol figures at the top of these ranges assume 99 RON fuel, such as Shell V-Power or Tesco Momentum 99, which we recommend on every tuned petrol car.
Check the figures for your BMW
Outputs vary by model, year and variant, and the condition of the car and the fuel it runs on make a difference too. For the expected figures on your exact BMW, enter your registration on our power gains check.
Gearbox tuning for automatic BMWs
Most of these cars have the ZF 8-speed automatic. After a remap, gearbox (TCU) tuning can raise torque limits, sharpen shift times and help the gearbox make the most of the extra torque. It can be done in the same visit. See our gearbox tuning page for details.
Is a BMW remap safe?
On a healthy, well-maintained engine, yes. Problems after a remap usually come down to one of three things: an underlying engine fault that was already there, poor maintenance, or a sensitive engine that needs the power dialling back slightly. That's why we check every car over before tuning. If we find something that needs attention, we'll tell you before going any further.
A few things help keep a tuned BMW healthy:
keep up with servicing and oil changes
let the engine warm up before using full power
on petrols, use 99 RON fuel
We've answered the most common worries in our ECU remap myths post.
What to expect on the day
1. Pre-tune checks. We check the car over before anything is changed.
2. Read and save. We read your original software and save it, so the tune can always be reversed.
3. Write the new software. Your custom Stage 1 calibration is written to the ECU.
4. Final checks. We check for faults and make sure everything is running as it should.
A Stage 1 remap takes 60–90 minutes, though some newer BMW ECUs take a little longer to read. If your tune is ever wiped, for example by a dealer software update, our software warranty covers reinstalling it. Remember to tell your insurer, as a remap is a modification.
Going further: Stage 2
If you want more from a 20i in particular, a Stage 2 build with an uprated intercooler, intake and downpipe goes further than software alone. Read about Stage 2 tuning and the parts you need. For a wider look at what a remap offers, see the benefits of ECU remapping.
For 20d owners, we also offer DPF delete and other diesel software solutions, intended for off-road and motorsport use.
BMW remapping in Hertfordshire
We're based in Ardeley, Hertfordshire, a short drive from Stevenage, Hitchin, Letchworth, Hertford, Welwyn and St Albans, and we see BMWs from all over the UK. We've tuned over 5,000 cars and have over 300 five-star reviews, which you can read on our reviews page. You can spread the cost with Klarna or Clearpay. See all our performance tuning options.
BMW remap FAQs
How much power does a BMW 320d remap add?
On the 190bhp B47 320d, a Stage 1 remap typically takes it to around 225–240bhp and 460–500Nm. It varies by car.
Is a 330i worth remapping?
Yes. The 258bhp B48 typically reaches around 300–310bhp and 450–470Nm at Stage 1, with a big improvement in mid-range pull.
How long does a BMW remap take?
60–90 minutes for a Stage 1 remap in most cases. Allow a little longer if you're adding gearbox tuning.
Can a BMW remap be reversed?
Yes, always. We save your original software before writing anything.
Will a dealer know my BMW has been remapped?
It's possible. Check your warranty terms before tuning, and tell your insurer.
Book your BMW remap
Send us your registration and tell us what you want from the car. Book online or get in touch.
