H4D: Cleaning throttle body without dismantling

Introduzione

Applies to H4D engine only.

This is a simple method of cleaning the throttle body without removing it. It is sufficient in most cases and offers remarkable results. Because of its simplicity and the short time it takes, it is advisable to carry out this operation every time the air filter is changed.

The vehicle must be on a slight upward slope or slightly elevated so that the front is tilted upwards and the rear (engine) is tilted downwards.

The aim is to allow fluid and impurities to drain naturally from the throttle body.

Cosa ti serve

Passo 1 Accessing the engine hood

H4D: Cleaning throttle body without dismantling, Accessing the engine hood: passo 1, immagine 1 di 1

Open the trunk.
Put aside the trunk carpets.

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Passo 2 Acessing the engine compartment

H4D: Cleaning throttle body without dismantling, Acessing the engine compartment: passo 2, immagine 1 di 1

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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Passo 3 Remove the air filter housing

H4D: Cleaning throttle body without dismantling, Remove the air filter housing: passo 3, immagine 1 di 2

H4D: Cleaning throttle body without dismantling, Remove the air filter housing: passo 3, immagine 2 di 2

Using a screwdriver, loosen the two Torx T25 screws on the air filter cover.
Remove the cover by moving it forward and then lifting it.

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Passo 4 Clear the air duct

H4D: Cleaning throttle body without dismantling, Clear the air duct: passo 4, immagine 1 di 2

H4D: Cleaning throttle body without dismantling, Clear the air duct: passo 4, immagine 2 di 2

Disconnect the oil vapour breather.
Loosen the hose clamp on the pipe leading to the throttle body using a flathead screwdriver.
Remove the pipe and airbox cover. Set the filter aside if it is to be used again later.

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Passo 5 Cleaning the throttle valve

H4D: Cleaning throttle body without dismantling, Cleaning the throttle valve: passo 5, immagine 1 di 3

H4D: Cleaning throttle body without dismantling, Cleaning the throttle valve: passo 5, immagine 2 di 3

H4D: Cleaning throttle body without dismantling, Cleaning the throttle valve: passo 5, immagine 3 di 3

Spray brake or contact cleaner on the throttle and use a soaked paper towel to clean it until the body and edges are clean.
It is recommended to wear gloves while handling the break cleaner.
Allow to dry for a few minutes before refitting the airbox.
When the ignition is switched on, the throttle valve defaults to the idle position, but it can be opened fully by holding the accelerator pedal to the stop.
If the accelerator pedal is released, even slightly, the throttle will close, risking cuts to fingers and damage to the gearbox motor!

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Passo 6 Refitting the airbox

Replace the pipe as far as it will go.
Tighten the clamp screw with a flathead screwdriver while holding the pipe in its correct position.
Reinstall the air filter.
Replace the cover by sliding it towards the notches.
Re-tighten the two Torx T25 screws while maintaining slight pressure on the cover.

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Passo 7 First restart

The throttle position sensor is set when the ignition is switched off (you will hear a click/click sequence from the throttle). Using an OBD tool is not necessary. The only function available fully resets all parameters, and requires the following step in any case.
Turn it on and off a few times in a row, letting the learning sequence unfold entirely each time.
Depending on how dirty the throttle body initially was, the first restart after cleaning is very likely to fail, even if the engine was warm. This is completely normal.
Once the engine has started, allow some time for the computer to find its new idle position. Help the engine with the throttle pedal if it verges on stalling.