MS43 MAP Sensor Conversion

Why Convert MS43 to MAP?

On a boosted M54, manifold pressure gives the ECU a direct measurement of the pressure actually being seen by the engine.

Our MAP-enabled MS43 calibration uses this manifold pressure signal as the ECU's main engine load input, making it particularly well suited to turbocharged and supercharged applications where airflow and boost levels may be far outside the factory operating range.

You retain the factory MS43 ECU and its normal diagnostics, VANOS control, idle control and vehicle integration, while using a load strategy designed specifically for a boosted engine.

Suitable For

• Turbocharged M54 engines
• Supercharged M54 engines
• Stock-internal boost builds
• Forged engine builds
• Large turbo installations
• Cars requiring wideband datalogging
• Cars using ECU-controlled boost solenoids

Pre-Terminated Adapter Harness

The harness is supplied with the correct ECU terminals already fitted. There is no need to crimp your own ECU pins or build a loom from scratch.

MAP Sensor

The harness is designed for the Bosch MAP sensor:

The sensor should be securely mounted using its built-in mounting eyelet and connected to a reliable inlet-manifold vacuum / boost source.

Inlet-Manifold Pressure Source

The MAP sensor must be connected to a reliable inlet-manifold pressure source downstream of the throttle body.

A dedicated manifold take-off is preferred to T-piecing into another vacuum line wherever possible.

The rear of the M54 inlet manifold has several vacuum take-offs. On many cars, one of these is unused and simply blanked off. This makes an excellent dedicated MAP sensor pressure source.

Important: The MAP sensor is the ECU's primary engine-load signal. Do not connect it to intake pipework or charge pipework before the throttle body.

Example of a blanked-off vacuum take-off on the rear of the M54 inlet manifold.

Wideband Datalogging

The harness includes an optional wideband input connection.

Connect the 0–5 V linear analogue output from a suitable wideband controller and the ECU can log lambda / AFR alongside the normal MS43 engine data.

Electronic Boost Control

An optional switched-ground output is included for control of a MAC valve or similar boost-control solenoid.

This allows boost-control strategies to be incorporated into the MS43 calibration without requiring a separate standalone boost controller.

Installation

Installation involves opening the relevant MS43 connector, moving the existing +5 V supply terminal, and inserting the supplied MAP power, ground and signal wires into the specified positions.

Full step-by-step instructions, ECU connector diagrams and installation photographs are provided in our guide.

What We Need From You

For the calibration, we will normally need details of your engine and hardware:

• Engine size and specification
• Turbo or supercharger type
• Injector size
• Fuel type
• Boost target
• Wideband controller, if fitted
• Boost-control hardware, if fitted

Worldwide Remote Mapping

Customers worldwide can use the fantastic MS4X Flasher and a suitable K+DCan cable to read and write the factory MS43 ECU.

We can review logs and revise the calibration remotely, allowing the MAP conversion to be tuned without the vehicle being physically present with us in Manchester, UK.