How to Clean the Throttle Body on a Mitsubishi Evo X

Introduction to the Mitsubishi Evo X Throttle Body

The Mitsubishi Evo X is an iconic high performance sports sedan known for its rally racing heritage. Under the hood sits a powerful, turbocharged 4B11T 2.0L engine putting out nearly 300 horsepower in stock form. Ensuring optimal airflow into this forced induction powerplant is critical for delivering strong acceleration and throttle response.

Like all modern vehicles, the Evo X utilizes electronic throttle control rather than a traditional cable-actuated butterfly valve. This electronically controlled throttle body carefully meters incoming air and allows the engine computer to precisely govern power output.

Symptoms of a Dirty Evo X Throttle Body

Over time, oil, fuel, and carbon deposits can accumulate on the throttle plate and bore of the Evo X throttle body. This buildup restricts airflow into the intake, potentially causing numerous symptoms including:

• Rough idle
• Hesitation or stumbling on acceleration
• Reduced power and throttle response
• Increased emissions and fouled spark plugs

When to Clean the Throttle Body

Mitsubishi recommends cleaning the Evo X throttle body every 45,000 miles. However, more frequent cleaning may be necessary if you notice any symptoms of restricted airflow. Cleaning the throttle body is also recommended whenever installing a new air filter, upgrading the intake system, or tuning the ECU.

How to Clean the Evo X Throttle Body

Cleaning the throttle body on an Evo X is straightforward project you can tackle in under an hour with basic hand tools. Here is a step-by-step guide:

Materials and Tools Needed

• Throttle body cleaner
• Shop rags
• Wire brush
• Flashlight
• Hex socket set

Step 1: Disconnect the Battery

Start by locating the battery in the trunk and disconnecting the negative terminal. This will prevent any errant sparks during the service.

Step 2: Detach Components for Access

There are several engine components limiting access to the throttle body assembly. Remove the intake piping, air filter housing, battery tray, and all associated hoses/wiring.

Step 3: Remove the Throttle Body

With better access obtained, locate the 4 bolts fastening the throttle body to the intake manifold. Loosen them slowly and evenly to avoid damage. Carefully maneuver the throttle body out of the engine bay.

Step 4: Clean Exterior Surfaces

Spray throttle body cleaner liberally on all accessible surfaces of the throttle body and plate. Allow it sit for a few minutes before wiping clean with a shop rag.

Step 5: Brush Interior Passages

Use a thin wire brush dipped in cleaner to gently remove any stubborn deposits inside the throttle bore and passages. Take care avoid damaging any internal electrical components.

Step 6: Rinse Components with Cleaner

Give the throttle body one final spray down with throttle body cleaner and let it drain off. Double check that all passages are debris free and wipe off any fluid puddles or drips.

Step 7: Reinstall Throttle Body

Carefully insert the freshly cleaned throttle body back into the intake manifold. Reinstall the 4 mounting bolts and torque them to the factory specification.

Step 8: Reconnect Components

Finish up by reconnecting all hoses, wiring, and accessories detached for access. Don't forget to also reconnect the negative battery terminal once complete.

FAQ

Is throttle body cleaner safe for sensors?

Yes, high quality throttle body cleaners are specially formulated to be sensor safe for use on modern electronic throttle bodies.

How often should I clean the throttle body?

Mitsubishi recommends cleaning it every 45,000 miles, but performing the service more often can't hurt, especially if acceleration issues are noticed.

Can a dirty throttle body cause a check engine light?

It's possible. A severely restricted throttle body can set various air flow related fault codes and trigger the check engine light.

What happens if I don't clean the Evo X throttle body?

Performance and fuel economy will slowly degrade. More severe accumulation may cause drivability issues, hesitation, power loss, stalling, or failed emissions tests.

Get Your Evo Running Smoothly Again!

Overlooking routine maintenance like throttle body cleaning can allow once negligible buildup turn to troublesome deposits in the intake. Fortunately, servicing the unit is straightforward DIY project for any Mitsubishi enthusiast. Follow the steps above to have your Evo X running cleanly again!

FAQs

Can I use carburetor cleaner instead of throttle body cleaner?

No, carburetor cleaner is much too harsh and may damage sensors or plastic components. Always use a high quality throttle body cleaner specifically designed for modern fuel injected engines.

How do I reset the ECU after cleaning the throttle body?

Resetting or recalibrating the ECU after throttle body cleaning is not necessary on the Evo X. The engine computer will automatically adjust fuel trim to account for any changes in airflow.

Will cleaning the throttle body improve gas mileage?

Possibly. Eliminating restrictions that negatively impact airflow can help optimize fuel economy. However many factors affect MPG so gains will vary.

What causes the throttle body to get so dirty?

Oil vapors, fuel residue, airborne debris, blow-by gasses, and other contaminants accumulate over time. Turbocharged and direct injection engines tend to build heavier deposits faster.