Our platform: AutoDX Pro — root-cause diagnostics & shop software autodxpro.com ↗
ECU · DME · TCU software

Tuned for your car.
Not just your model.

Engine and transmission calibrations built around the hardware you actually have — engine wear, fuel system, boost, altitude and the fuel in your tank.

91 · 93 · E40Maps for your fuel
LoggedEvery tune verified
$0Log reviews & seasonal fixes
Bayrabbit rabbit emblem Bayrabbit rabbit emblem

Find your tune

Pick your car — reasonable, engine-safe numbers. SUVs keep extra margin for towing and altitude.
What we do

Software first.
Wrenches coming soon.

ECU

ECU & DME tuning

Engine calibrations: boost, timing, fueling, torque limits. Ready or custom, delivered online.

Engine tunes

TCU tuning

Transmission software: faster, smoother shifts and torque limits that match your engine tune.

Transmission tunes

Custom performance

Tuned on your datalogs for your mods, your fuel and your altitude — as far as your hardware safely goes.

Why custom
Soon

Auto repair & service

Diagnostics, maintenance, repair and installs in our own shop. Opening soon.

Get notified
Two ways to tune

Ready tune or custom tune?

A Ready Tune is a proven map with moderate gains and a safety margin built in — it has to be safe for every healthy car of your model. A Custom Tune is calibrated for one car: yours.

Off the shelfFlash right away

Ready Tune

Safe, proven, mid-level settings for a healthy stock car. Buy, download, flash.

Power gain
Fit to your car
  • Moderate power and torque gains
  • Conservative timing and boost targets with a built-in safety margin
  • Pick your fuel: 91 or 93 octane
  • For stock cars or light bolt-ons
  • Flash it with the dongle right after checkout
  • Tune Care included: free log reviews + season check
Online$700+ dongle
Buy Ready Tune

At our shop: $700 — no dongle needed

Locked BMW DME? Unlock with your tune: +$100

Built for your hardwareMost power

Custom Tune

We tune your actual car. Your datalogs show what your engine, fuel system and turbo can really do — and we calibrate right up to that, safely.

Power gain
Fit to your car
  • The most power your setup can safely make
  • Calibrated on your datalogs — revision after revision
  • Any fuel: 91, 92, 93 or ethanol blends like E40
  • Accounts for engine wear, fuel pump limits, boost and altitude
  • Stock, bolt-ons or big-turbo builds
  • Towing or mountain driving? We tune for your load and altitude
  • Built for the hardware you declare — later hardware or fuel changes are a paid revision
  • Tune Care included: free log reviews + seasonal revisions
Online · from$1,000+ dongle
Start Custom Tune

At our shop: from $1,000 — no dongle needed

Locked BMW DME? Unlock with your tune: +$100

Add a TCU (transmission) tune to either one: +$300. Not sure which one? Tell us about your car — we'll tell you honestly if a Ready Tune is enough.

Bayrabbit Tune Care · included

We don't flash
and forget.

Every tune is verified on your car's real datalogs — on day one, after it settles in, and again when the season turns. Logs are required. Reviewing them costs you nothing, and so do the changes they lead to.

$0Every log review
$0Revisions from our checks
3Required checkpoints
24hEvery log read by a real tuner within 24 hours
$0
Check 01
Day 1

Flash-day log

Before you drive it hard, record a log. We confirm boost, fueling, timing and knock are right where they should be.

$0
Check 02
500–1,000 mi

Settled-in check · 2–4 weeks

By now your ECU's fuel trims and knock learning have adapted, and you've burned a few tanks of fuel. We look again with fresh logs.

$0
Check 03
Next season

Season check

Tuned in winterLog again on the first 85°F+ (30°C+) days. Heat soak and hot intake air bring out knock that cold weather hides.
Tuned in summerLog again in the first cold snap, below 40°F (5°C). Dense air pushes airflow and boost up; ethanol blends start harder.
Same car. Same map. 55°F apart.That's why one log is never enough.
Tuned in January35°F · cool, dense air
Re-checked in July90°F · heat soak, hot intake air
0°F32°F60°F110°F
Logs are required

Every dongle tune — ready or custom — comes with mandatory datalogs. No logs, no guesswork. It's how we stand behind your engine.

Changes from our checks: $0

If a check shows your car needs a change — summer heat, winter cold, a pump that can't keep up — we revise the map at no extra cost. New hardware or a different fuel is a new, paid revision.

Flashed at our shop?

No dongle needed — we flash it and log it ourselves.

Tune PassportBR-1042
2020 BMW M340i
B58 3.0T · DME Custom · Rev 2
Fuel93 + E30
TunedOct 2026 · 48°F
Logs reviewed3
Revisions cost$0
Next check~1,000 mi
Season checkFirst 85°F+ days
✓ Log-verifiedEmail reminder before every check
Why custom

Same model.
Different car.

Two identical cars leave the factory the same — and stop being the same a few thousand miles later. A ready map has to stay safe for all of them. A custom map is written for one.

Datalog: fuel rail pressure
TargetYour car
350300250200 2k3k4k5k6k7k RPM BAR Pump falls behind here → custom map limits load, not your engine

Illustrative example. A ready map can't see this — it assumes a healthy pump. A custom tune is built from your logs, so we tune around it.

Engine wear

Mileage, compression and carbon build-up change how much timing an engine tolerates.

Fuel pump (HPFP)

Some pumps can't hold rail pressure at high RPM. We see it in your logs and tune around it.

Boost & air

Turbo health, boost leaks, intake and intercooler all change what's safe.

Octane & ethanol

91, 92, 93 or E-blends like E40 — each fuel needs its own timing and fueling.

Altitude & climate

In thin mountain air the turbo spins faster for the same boost, and hot days bring knock. Your map should know where you drive.

Your mods

Intake, downpipe, intercooler, injectors, turbo — tuned together as one system.

Shop

Popular ready tunes

DMEEngine

B58 3.0T Ready Tune

BMW G-series 340i · 540i · X3 M40i

91 oct93 oct
$700+ dongleAdd to cart
TCUTransmission

ZF 8HP TCU Tune

8-speed automatic · faster shifts, raised torque limits

ComfortSport
+$300with engine tuneAdd to cart
ECUEngine

EA888 2.0T Ready Tune

VW GTI · Golf R · Audi A3 / S3

91 oct93 oct
$700+ dongleAdd to cart
Don't see your car, or want more than a ready map? Request a custom tune
How a custom tune works

From stock file to dialed in

01

Tell us about your car

VIN, mods, fuel, altitude and what you want from it.

02

Send your stock file

Read it with the dongle and upload it to your account. We keep a copy, always.

03

Get revision 1

A base calibration for your exact hardware and fuel.

04

Log & revise

Upload datalogs — required, and every review is free. We refine timing, boost and fueling.

05

Dialed in — then re-checked

Final map in your account. Tune Care checks it again at 500–1,000 miles and next season.

ECU & DME unlock · in shop or by mail

Locked DME?
We unlock it.

Since mid-2020, most BMW DMEs leave the factory locked against tuning. We unlock supported DMEs right here in our shop — bring the car in, or mail us the DME.

With a Bayrabbit tune $100

Per DME, when you tune with us — ready or custom.

Unlock only $200

Per DME. Not tuning with us? We unlock your BMW DME and you're done.

Mercedes, Audi & send-outs Quote

Newer Mercedes-Benz, Audi and other ECUs — and DMEs we have to send out for unlock. Price on request.

Heads up: unlocking returns the DME to stock — any tune already on it is erased.

Not near us? Mail it in

Ship us your DME — same price: $100 with a tune, $200 unlock only. You cover shipping both ways.

Two DMEs? ×2

V8 and V12 engines with two DMEs — the price is per DME.

Can't unlock it in our shop?

Some units, like the S68 DME9, have to be sent out for unlock. We handle it — price on request.

BMW DME compatibility

We identify your DME on the bench first — you'll know before we start.
EngineExample modelsStatus
B46 / B48 2.0T · Bosch230i · 330i · 430i · X3 30i · MINI · Supra 2.0Unlock in shop
B58 3.0T Gen 1–2 · BoschM240i · M340i · M440i · 540i · X3 M40i · X5 40i · Z4 · Supra 3.0Unlock in shop
S58 3.0TM2 · M3 · M4 · X3 M · X4 MUnlock in shop
N63 / S63 4.4T V8M550i · X5 M50i · M5 (F90) · X5 M · X6 M · M8Unlock in shop
S68 4.4T V8 · DME9M5 (G90) · XM · X5 M60i · 760iSent out · on request
B58 Gen 3 · Vitesco DME92025–2026 M340iNot yet
S58 latest production2025–2026 M3 · M4Not yet

Supported cars: through model year 2024. 2025+ cars — we check your DME first. “Vitesco” printed on the DME case means Gen 3: not unlockable yet. The list changes as new unlocks are released — ask us about your car.

Your account

Your garage.
Every file.

  • All your purchased tunes and downloads in one place
  • Custom tune progress, revision by revision
  • Upload datalogs and message your tuner
  • Your stock file, saved — return to stock anytime
  • Tune Passport with your next check date and email reminders
bayrabbit.com/account
2020 BMW M340iB58 3.0T · ZF 8HP · 93 + E30
Rev 2 — log it
Ordered
Stock file
Rev 1
Logs
Rev 2
Final
M340i_DME_rev2_93-E30.binOct 12Download
M340i_DME_stock_backup.binSep 28Download
Service bay

Our shop is coming soon

Diagnostics, maintenance, repair and performance installs — done in-house by the same people who write your tune.

DiagnosticsMaintenanceRepairInstallsDyno & logging
Bayrabbit Engineering shop sign concept Coming soon
Our diagnostics platform

Diagnose first.
Then tune.

Check engine light, misfire or a weak pull? Find the cause before you add power. AutoDX is our own diagnostics platform: enter a VIN, fault codes and symptoms — three independent expert assessments are checked against factory repair manuals and reconciled into one root-cause verdict, with the exact parts to fix it.

  • Root cause, not guesses — factory manuals for Audi, VW, BMW, Mercedes & Porsche
  • Any scanner works — even a photo of its screen
  • For shops: repair orders, estimates approved by link, inspections, parts and payments
Open AutoDX Pro ↗
Consensus verdict · example
2019 Audi Q5 · 2.0 TFSIVIN ✓
P0301 · Misfire, cylinder 1
✓ Ignition coil #1 — root cause confirmed
Assessments agree: 3/3Parts: ignition coil (1) · spark plugs (4)
Bayrabbit tipTune a healthy engine. A misfire under boost only gets worse — find the cause on AutoDX, fix it, then tune.
FAQ

Good questions

What's the difference between ECU, DME and TCU?

ECU and DME both control the engine — DME is simply BMW's name for it. The TCU controls the automatic or dual-clutch transmission: shift speed, shift points and torque limits.

Is a Ready Tune safe?

Ready Tunes use moderate targets with a safety margin, for healthy cars on the fuel you select. If your car is modified, high-mileage, or you want more power, go Custom.

Can I tow or drive in the mountains with a tuned SUV?

Yes — that's how we tune SUVs. They get extra margin: torque is held in check under heavy load, and boost is pulled back at altitude, where thin air makes the turbo spin faster for the same boost. Towing often or living up high? Go Custom and tell us your trailer weight and where you drive.

Why are datalogs required?

Because every car is different — and a log is the only way to see yours. We check your logs on flash day, after 500–1,000 miles and again next season. We review every log within 24 hours. Changing fuel or adding mods? Send a log before you push it.

Do I pay for log reviews or seasonal changes?

No. Log reviews are always free, and if a Tune Care check shows your map needs a change, the revision is free too. A Custom Tune is built for the hardware and fuel you told us about — if you change them later (new turbo, intake, injectors, a different fuel), that's a new, paid revision.

What if my car can't be flashed?

You get your money back for the tune. If something else goes wrong, we refund up to the price of the tune — that's the maximum. See our Terms & Disclaimer.

Is there a warranty?

No. Tuning is a modification of your car's software and every tune is custom work, so we can't give a warranty or take responsibility for the engine, transmission or other parts. In any case, the most we refund is the price of the tune. Tuning may also affect your factory warranty.

What is the dongle?

A small device that plugs into your car's OBD port. You use it to flash your tune and record datalogs for us. Getting flashed at our shop? You don't need one.

My BMW DME is locked. Can you unlock it?

Most supported Bosch DMEs — yes: $100 per DME with a Bayrabbit tune, $200 per DME for unlock only. Bring the car in, or mail us the DME (you cover shipping both ways). Unlocking returns the DME to stock, so any tune already on it is erased. Two DMEs (V8 / V12) cost ×2. 2025–2026 M340i (Gen 3 B58, Vitesco DME) and the newest 2025–2026 M3/M4 can't be unlocked yet. Mercedes, Audi, other brands and DMEs we have to send out — price on request.

Which fuel should I choose?

The fuel you actually buy. A 93 map on 91 fuel isn't safe. Running ethanol blends like E40? That's a Custom Tune — we tune for your exact blend.

Can I go back to stock?

Yes. Your stock file is saved in your account and can be flashed back anytime.

Do I need to visit the shop?

No — buy online and flash with the dongle. Prefer in person? We can flash and log it at our shop, no dongle needed. Full repair service is coming soon.

Design