H4D: MAP Sensor Cleaning

Written By: AntonioTwingo
  • Comments: 1
H4D: MAP Sensor Cleaning

Difficulty

Easy

Steps

5

Time Required

10 minutes

Introduction

Applicable only to the H4D engine.

The intake air pressure sensor (MAP Sensor) measures the air pressure in the intake. This allows the engine control unit (ECU), using specific formulas, to calculate the amount of air being drawn in and adjust the fuel injection accordingly.

A dirty MAP sensor can cause unpleasant jerking and an unstable idle.

If the sensor becomes faulty or is disconnected, the following symptoms may occur:

- ESP warning light on the dashboard with a key symbol.

- Cruise control and speed limiter inoperative.

- Very high idle, stuck at ~1150 RPM even when the engine is warm.

- Full throttle opening at the end of the pedal travel is impossible.

- Air conditioning not working.

- Engine power is limited.

A faulty sensor will trigger an OBD error code, which may not be readable by all diagnostic applications.

The OBD code and warning lights will disappear on their own after the engine has run for a short time following the replacement or cleaning of the sensor. It may be necessary to move the vehicle for the warning light to turn off by itself.

Once the warning light disappears, the idle speed should automatically drop back to 800 RPM as expected.

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    • Open the trunk.

    • Put aside the trunk carpets.

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    • Unscrew the 6 T50 screws by hand or using a wrench and a socket.

    • Lift and put aside the engine hood.

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    • Disconnect the pressure sensor connector.

    • Gently remove the pressure sensor by pulling it upwards. The sensor must be rotated in a specific way to be removed.

    • The sensor is difficult to extract, even with slim fingers. Those with thicker fingers may not be able to perform this operation without using a tool.

    • Breaking the MAP sensor during removal would require removing the intake manifold, which is a complex procedure.

    • Gently spray contact cleaner in short bursts into the pressure sensor's orifice.

    • Shake the sensor, allow the liquid to drain out, and repeat the process several times.

    • Let the sensor dry for a few minutes.

    • Certain products, or simply repeated cleaning combined with wear, will eventually lead to the inevitable replacement of the MAP sensor.

    • Bosch Motorsports recommends:

    • Lubricating the seals with a drop of engine oil (e.g., 5W40).

    • Avoid using silicone-based lubricants or grease.

    • Insert the pressure sensor into its position until it is fully seated.

    • Reconnect the pressure sensor connector.

Conclusion

Congratulations! You've just cleaned your intake pressure sensor!

Author

AntonioTwingo

Member since: 24/08/22

6467 Reputation

One comment

Attention , cette intervention a l’air facile à faire donc je me suis dit pourquoi pas …

En retirant le capteur, la tétine tenue par deux joints c’est cassé à l’intérieur du collecteur d’admission d’air 🤦‍♂️pourtant j’y suis allé doucement !

J’ai aussitôt commandé un nouveau capteur m.a.p

J’ai dû démonter le collecteur d’admission d’air pour retirer ce gros bout de plastique qui se baladait dedans car il risquait de finir dans une soupape et de faire de gros dégâts…

Pour démonter le collecteur d’admission d’air j’ai dû démonter :

Tuyau de boîte à air,boîtier papillon,rampe d’injection,pot d’échappement, catalyseur, tuyaux de liquide de refroidissement, câble électrique, mettre la voiture sur chandelles de chaque côté pour pouvoir dévisser les deux boulons de Silent bloc moteur et faire descendre le moteur de 20 cm environ à l’aide d’un cric car c’est la seul façon de retirer ce collecteur d’air

La voiture n’a pas roulé 1 semaines le temps que le nouveau capteur m.a.p arrive.

Donc faite attention !

Philippe -