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ENGINEERING THE FUTURE OF PERFORMANCE ™
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M139 E-Performance ECU Tune
    M139 E-Performance ECU Tune
    Purchase M139 E-Performance ECU Tune
    • SKU: M139-E-Performance-ECU-Tune

      M139 E-Performance ECU Tune

    • Power gain Up To

      +100 HP

      Torque gain Up To

      +100 TQ

      Advertised gains are estimates of HP and Torque “at the engine” calculated from gains as measured on a Dynojet Dynamometer in ideal conditions and typically show the largest possible change.  Actual gains are dependent on the following: Learn More about Crank HP Vs Wheel HP

      Model – Manufacturers use the same engine in multiple model vehicles and often times they are in a different state of tune, for example: 2008 C63 and a 2008 CLK Black Series.  Both have the same engine, but the C63 has 451hp while the CLK63 has 500hp.  Naturally the C63 will show more gains as it starts at a lower level.

      Model Year – Similar to above, as time progresses, Manufacturers tend to slightly increase power output via software from one year to the next or offer “Performance Packages” with increased power.  The engines remain largely unaltered and as a result, final tuned output remains the same, while the gains are lower as the starting point is now higher.

      Fuel – Fuel quality is HIGHLY important with performance vehicles.  Low quality and/or low octane fuel will greatly impact engine output and potentially even engine health.  Top tier brand premium fuels should always be used to achieve the best results possible.

      Drivetrain – All wheel drive has higher drivetrain losses than rear wheel drive.  This results in lower numbers when testing on a chassis dyno.  Wheel/tire size and weight will also impact chassis dyno results

      Weather/Conditions – Temperature, humidity, altitude, and air density all impact engine performance.  Heat, high humidity, and thin air will all work towards reducing engine output

      Engine Health – Higher miles tends to result in increased build up and lower compression which can and will impact engine output.  Properly maintained engines will have better performance than abused or neglected engines.

      Supporting modifications – The highest power levels require supporting modifications.  Depending on the engine, this could mean forged internals, built transmission, upgraded fuel system, 110+ octane race fuel, etc.
    • Stage:
    • Choose from Recommended Products (Optional):

    • $1,500.00 $1,500.00

    • How To Tune
    • Prop 65 warning
      Warning

      This product can expose you to chemicals including carbon black, silica - crystalline, formaldehyde, and lead which are known to the State of California to cause cancer, and lead, which is known to the State of California to cause birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.
    Weistec Horsepower 771
    Weistec Torque 852
    Manufacturer Weistec
    Street legal in all the US States No
    Engine Family M139
    Stock Horsepower 671
    See more
    year make model trim engine
    2026 Mercedes-Benz C63 AMG S E-Performance Estate (S206) Turbocharged 2L I4 (M139)
    2025 Mercedes-Benz C63 AMG S E-Performance Estate (S206) Turbocharged 2L I4 (M139)
    2024 Mercedes-Benz C63 AMG S E-Performance Estate (S206) Turbocharged 2L I4 (M139)
    2023 Mercedes-Benz C63 AMG S E-Performance Estate (S206) Turbocharged 2L I4 (M139)
    2022 Mercedes-Benz C63 AMG S E-Performance Estate (S206) Turbocharged 2L I4 (M139)
    2026 Mercedes-Benz GLC63 AMG S E-Performance Coupe (C254) Turbocharged 2L I4 (M139)
    See more

    Product Description


    This longitudinally-mounted, electrically-assisted version of the M139 four-cylinder does something bold: it replaces AMG's traditional V8 as the combustion engine in the C63 S E-Performance and GLC63 S E-Performance, paired with a rear-axle electric motor and a small high-voltage battery. The combustion engine alone already makes well over 450 hp, and combined with the electric motor's contribution, total system output reaches deep into supercar territory. It's a genuinely different application of the M139 architecture than AMG's compact cars use, engineered from the ground up to work as one half of a hybrid drivetrain rather than stand alone.

    Weistec's calibration takes on the combustion half of that hybrid powertrain with an OEM-level ECU recalibration that works with the factory's turbo, timing, and boost management rather than around it, leaving the electric motor, battery, and every factory protection system exactly as engineered. It's calibrated specifically for this hybrid application, not carried over from the standalone M139 tune, because a car already reaching into supercar territory deserves a calibration built just for it. Factory output of 671 hp and 752 lb-ft climbs to 771 hp and 852 lb-ft with our recalibration.

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    How Do You Get Your M139 E-Performance ECU Tune Tuned?

    Follow these steps — this is what your specific vehicle needs and supports.

    1

    Unlock Check

    This ECU requires an unlock first

    Modern ECUs are often locked down, especially after a dealer software update, which can block bench flashing or OBD flashing. Our ECU Unlock Service removes those restrictions, is done per ECU, and stays active through most future dealer updates as long as the bootloader isn't overwritten.

    Read the full ECU Unlock breakdown →
    2

    Choose Your Tune Stage

    3

    Core Improvements

    Standard with this tune
    • Increased Horsepower
    • Increased Torque
    • Improved Throttle Response
    • Optimized Fuel and Spark
    • Increased Boost
    • Top Speed Limiter Removed
    4

    Free Add Ons

    Want it louder?

    Read more about Burble & Pops →

    This tune can have Burble/Pops added or increased on deceleration, at no additional charge. Select an intensity below and we'll add it to your order, or mention it when requesting your tune — through the Cypher+ app, your calibration request form, or when placing your order.

    5

    Pick Your Tuning Method

    See the full tuning process →
    1Selected

    Cypher Plus

    Order a Cypher Plus and tune your car yourself from your phone, entirely through the MyFlasher app. Watch how it works.

    2Selected — Pick return shipping at checkout

    Mail It In

    Remove your ECU or TCU and mail it to us for tuning. Required for some applications.

    3Selected — Pick Will call at checkout

    In Person

    Bring your vehicle, or just your ECU/TCU, to our Anaheim, CA headquarters. Call 714-202-0005 or email sales@weistec.com to schedule.

    4Selected — Order through your local dealer

    Cypher Pro Dealer

    Visit a certified Cypher Pro Dealer near you. Find one with our dealer locator.

    6

    Complete The Upgrade

    An ECU tune alone won't remove all factory limits or fix how power reaches the ground. Add these to round out the upgrade with no limitations.
    Read the full CPC & TCU breakdown →

    What is a CPC module?

    The CPC (Central Powertrain Control) is a separate control unit that manages things like the active exhaust valves, radiator fan, intercooler pumps, and speed limiter. On many newer Mercedes-Benz vehicles, it also houses torque limiters that can hold back an ECU tune from reaching its full potential.

    What is a TCU tune?

    A TCU (transmission control unit) tune delivers faster, firmer shifts with higher line pressure, reducing clutch slip and increasing the transmission's torque capacity. It's a worthwhile upgrade on its own, or paired with an ECU tune for a fully sorted powertrain.

    Your Total  

    Good to Know

    • This is a reflash of your original module, not a stand-alone unit.
    • Power gains vary by vehicle, modifications, fuel, and operating conditions (ambient temperature, altitude, etc.).
    • New or upgraded spark plugs are always recommended when tuning.
    • Product may not be emissions compliant. Check local laws prior to installation.
    • Always use a battery charger during programming.