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Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

Mitsubishi Chariot (Grandis/Space Wagon) 2.4 4G64 (1998): Throttle Body Cleaning and Adjustment

The throttle body on the 4G64 engine gets dirty from crankcase gases and deposits from the exhaust gas recirculation (EGR) system. This causes a fluctuating idle speed, hesitation during acceleration, and increased fuel consumption. Regular cleaning and calibration of the throttle position sensor (TPS) restore stable engine operation.

Difficulty: Medium Time: 1.5-2 hours Steps: 16 Tools: 10/12/14 mm socket set, flat-head and Phillips screwdrivers, multimeter (for TPS adjustment), clean lint-free rags

Part

  • 🔩 Throttle body gasket (MD180361 or MD322990), carburetor or throttle body cleaner (free of harsh solvents), new throttle body mounting bolts if needed

Step by step

16 steps
  1. Disconnect the negative battery terminal and let the engine cool down completely (at least 30 minutes).
  2. Remove the air duct between the air filter housing and the throttle body: loosen the clamps and disconnect the mass airflow (MAF) sensor connector if it is mounted on the duct.
  3. Disconnect the electrical connectors of the TPS and the idle speed control (ISC) motor on the throttle body housing.
  4. Disconnect the vacuum hoses from the throttle body. Mark their positions for correct reassembly.
  5. Remove the 2-4 bolts securing the throttle body to the intake manifold (12-14 mm socket) and take off the throttle body together with the old gasket.
  6. Place the throttle body on a clean surface with the throttle plate facing up. Inspect the inner surface of the bore and the throttle plate itself. Black carbon buildup and oily deposits are normal.
  7. Dampen a clean lint-free rag with carburetor cleaner. IMPORTANT: Do NOT spray the cleaner directly onto the throttle plate. The liquid can get into the throttle shaft bearings or the TPS and damage them.
  8. Carefully wipe the inner surface of the bore and the edges of the throttle plate with the damp rag. Do NOT remove the molybdenum coating on the edges of the throttle plate (the dark gray layer). It is a factory seal that minimizes air leakage when the throttle is closed.
  9. Do not loosen the screws that secure the throttle plate to the shaft. Doing so disturbs the factory calibration and causes idle problems.
  10. Wipe the mating surfaces of the throttle body and the intake manifold with a dry rag and remove any remains of the old gasket.
  11. Place the new gasket onto the intake manifold studs, install the throttle body, and tighten the bolts evenly in a crisscross pattern (tightening torque 10-15 N·m (7-11 lb-ft)).
  12. Reconnect the vacuum hoses according to your marks, plug in the TPS and ISC connectors, and install the air duct.
  13. Connect the multimeter to the TPS connector: black probe to ground (terminal 4 or the body), red probe to the signal terminal (terminal 2). Reconnect the negative battery terminal and turn the ignition on (do NOT start the engine).
  14. Check the TPS voltage with the throttle fully closed. It should be 0.53-0.74 V. If it is out of range, loosen the 2 TPS mounting screws, rotate the sensor until you reach the optimal value of 0.69-0.72 V, tighten the screws, and check again.
  15. Turn the ignition off and disconnect the multimeter. Start the engine. The idle speed may be unstable for the first 2-3 minutes (the engine control unit (ECU) is adapting to the new throttle position).
  16. Warm the engine up to operating temperature and let it idle for 5-10 minutes so the ECU can learn the new parameters. If the idle remains unstable, check all vacuum connections for leaks and check for air leakage past the gasket.

Common mistakes and warnings

  • Do not use harsh solvents (acetone, lacquer thinner) or abrasive materials. They damage the protective coating of the throttle plate and housing. If the idle speed remains unstable after more than 15 minutes of engine operation following the cleaning, the idle speed control motor may be faulty or air may be leaking through a damaged gasket.