The M133 Engine: A Powerplant Built for Performance

The Mercedes-Benz M133 turbocharged inline-4 engine, famously found in the CLA 45 AMG, GLA 45 AMG, and A 45 AMG, is a marvel of modern engineering. Producing up to 375 horsepower from just 2.0 liters, this engine relies on a high-pressure direct injection system and a twin-scroll turbocharger. However, like all forced-induction engines, its factory intake system is designed for a balance of noise suppression, cost, and packaging – not outright performance. The stock air box and intake ducting introduce unnecessary restriction, particularly as boost pressures rise. Replacing it with a purpose-built cold air intake such as the AWE Tuning unit is one of the most effective first steps toward unlocking the M133’s true potential.

AWE Tuning Cold Air Intake: Design and Engineering

AWE Tuning has earned a reputation for producing high-quality, dyno-verified induction systems for European performance cars. Their cold air intake for the M133 engine is no exception. It replaces the entire factory air pathway with a combination of a large, high-flow air filter (typically a dry or oiled cotton gauze element), a mandrel-bent aluminum intake tube, and heat-shielding that separates the filter from engine bay heat. The intake tube is carefully contoured to maintain laminar airflow and reduce turbulence, while the oversized filter element provides substantially more surface area than the stock paper filter. The result is a measurable reduction in intake restriction and a cooler, denser charge entering the turbocharger inlet.

Key design features include a full CNC-machined billet MAF (Mass Air Flow) sensor housing that maintains accurate airflow readings, and a carbon fiber or powder-coated aluminum heat shield that seals against the hood liner. The filter itself is positioned to draw air from a cooler region of the engine bay, often near the front grille or lower bumper area, ensuring that the temperature of the incoming air is as low as possible – critical for maximizing oxygen density and preventing knock.

Expected Performance Gains: Dyno-Verified Results

While butt-dyno impressions vary, independent dyno testing and owner reports consistently show gains of 10–15 horsepower and 12–18 lb-ft of torque at the wheels on a stock M133 vehicle. These numbers are not just peak gains; the AWE intake broadens the power curve across the mid-range, with particularly strong improvements from 3,000 to 5,500 rpm. The reduced restriction means the turbocharger can spool slightly faster, improving throttle response and reducing lag. On a stage 1 or stage 2 tuned car, the intake becomes even more beneficial, often allowing the turbo to hold boost more efficiently at higher RPMs.

It is important to note that gains can vary depending on ambient temperature, fuel quality, and the specific vehicle variant (e.g., A45 vs. CLA45). In warmer climates, the cold air intake’s heat shielding offers an even greater advantage over the factory system, which tends to heat-soak quickly during spirited driving. For precise before-and-after data, many owners have shared dyno sheets on enthusiast forums such as MBWorld and BenzWorld.

Beyond Horsepower: Throttle Response and Sound

Many drivers report a noticeably sharper throttle tip-in and a reduction in the “turbo lag” sensation typical of the M133’s stock calibration. The intake also dramatically improves intake noise: you’ll hear the whoosh of the turbo spooling and a distinct induction roar under full throttle. The sound is aggressive but not raspy, and many enthusiasts consider it one of the best aspects of the upgrade. For those who track or autocross their cars, the improved transient response can be worth more than the peak power gain.

Step-by-Step Installation Guide

The AWE Tuning cold air intake is designed for a direct bolt-on installation, requiring no cutting or permanent modifications to the vehicle. Most DIY owners with basic mechanical skills can complete the job in 1.5 to 2.5 hours. Below is a detailed walkthrough. Always refer to the official AWE installation instructions for torque specifications and any model-specific notes.

Tools and Materials Needed

  • 8mm, 10mm, and 13mm socket set
  • Flathead and Phillips screwdrivers
  • Torx T25 and T30 bits (for some M133 vehicles)
  • Pliers (for hose clamps)
  • Torque wrench (optional but recommended for hardware)
  • Clean rags and isopropyl alcohol (for cleaning surfaces)
  • Thread locker (if specified in instructions)

Preparation and Safety

  1. Disconnect the battery negative terminal using a 10mm wrench. This prevents any accidental airbag deployment or sensor issues.
  2. Remove the engine cover (if equipped) – typically held by a few push-clips or screws.
  3. Inspect the factory intake for any clips or brackets that may be hidden under the cabin air filter housing or around the radiator support.

Removing the Factory Air Intake System

  1. Unclip the electrical connector from the MAF sensor and carefully unseat the sensor from the intake tube using a T25 bit if bolted.
  2. Loosen the hose clamp connecting the intake tube to the turbocharger inlet using a flathead screwdriver or 8mm socket.
  3. Remove the bolts securing the factory air box to the engine bay (typically three or four 10mm bolts).
  4. Pull the entire factory intake assembly upward and out – it may require a slight twist to clear the strut tower brace or coolant reservoir.
  5. Clean any debris from the area where the new heat shield will mount.

Installing the AWE Tuning Cold Air Intake

  1. Position the heat shield in the factory air box location. Align the included brackets and hand-tighten the hardware. Do not fully torque until final alignment.
  2. Insert the new high-flow air filter into the heat shield housing. Ensure a tight seal with the included O-ring or gasket.
  3. Attach the intake tube to the turbo inlet using the provided silicone coupler and heavy-duty hose clamps. Tighten the clamp to 3–4 Nm (or as specified in instructions).
  4. Transfer the MAF sensor from the factory intake to the AWE billet housing. Use the provided Torx screws and apply a small amount of thread locker if recommended. Do not overtighten.
  5. Attach the intake tube to the MAF sensor housing using the additional silicone coupler. Ensure all connections are properly aligned – the tube should have no kinks or bending stress.
  6. Secure the MAF sensor electrical connector back in place and route the wiring harness away from any hot surfaces or moving belts.
  7. Torque all bracket and mounting bolts to the values listed in the AWE instructions (typically 8–12 Nm for M6 bolts).
  8. Double-check all hose clamps for tightness and ensure the filter is securely seated.

Final Checks and Testing

  1. Reconnect the battery negative terminal and verify that the terminal is tight.
  2. Start the engine and let it idle for 30 seconds to allow the ECU to adjust to the increased airflow.
  3. Inspect all connections for any signs of leaks – you can use a smoke machine or simply listen for unusual hissing sounds.
  4. Take a careful test drive, monitoring the vehicle for any check engine lights, abnormal noises, or loss of power. Most M133 ECUs will adapt without issues, but on rare occasions a “mass airflow plausibility” code can appear if the installation is not airtight. If this occurs, re-check all clamps and the MAF sensor orientation.

Cost Breakdown: Total Investment

The financial commitment for the AWE Tuning M133 cold air intake involves several components. Below is a realistic breakdown based on current market pricing (which can fluctuate).

ItemEstimated Cost
AWE Tuning Cold Air Intake Kit (includes filter, tube, heat shield, hardware)$349 – $429
Professional installation (if not DIY)$120 – $250
Optional: Replacement filter (dry type for maintenance)$40 – $70
Optional: Turbo inlet hose upgrade (for maximum flow)$100 – $180
Total DIY cost$349 – $499
Total with professional installation$469 – $749

Note that the AWE intake itself is available through many retailers and directly from AWE Tuning’s official website. If you are on a budget, consider looking for used kits on enthusiast forums, but be cautious of missing components.

Additional Costs to Consider

While the intake is a standalone upgrade, many owners combine it with a ECM tune (Stage 1) to fully exploit the improved airflow. A typical tune costs between $500 and $900. The combination often yields 40–60 wheel horsepower and transforms the car. If you plan to tune the car, the intake becomes a prerequisite rather than an optional upgrade. Also, if your M133 has high mileage (>60,000 miles), it is wise to replace the turbo inlet seal and clean the turbo inlet port while you have the intake off – these parts are low-cost but add labor savings.

Professional Installation vs. DIY

The installation is rated as moderate difficulty. Most mechanically inclined enthusiasts can handle it, but there are a few tricky points: removing the factory air box can be challenging on certain model years due to the tight fit around the sound generator tube and the coolant reservoir. Additionally, routing the AWE intake tube without rubbing against the power steering line requires patience. If you are not comfortable working on modern turbocharged engines, or if you lack a torque wrench, professional installation for $120–$250 is money well spent to avoid a costly mistake (such as a loose clamp that could allow un-metered air into the engine).

Potential Issues and Troubleshooting

Most installations are trouble-free, but a few common issues have been reported on forums:

  • Check Engine Light (P0101 or P0102): This is usually caused by a leak at the MAF sensor housing or a loose clamp. Verify that the MAF sensor is seated correctly and that all couplers are tight.
  • Whistling Noise at Idle: A slight whistle is normal due to the increased airflow, but a loud, high-pitched whistle often indicates a vacuum leak. Re-tighten all connections.
  • Heat Shield Rattle: If the heat shield contacts the hood liner or a bracket, you may hear a rattle at certain RPMs. Ensure that all mounting points are secure and add foam tape if necessary.
  • Intake Tube Contact: On some vehicles, the aftermarket intake tube may contact the coolant reservoir hose. A simple wrap with heat-resistant tape or a small adjustment to the clamp position solves this.

If you encounter persistent issues, consult the AWE Tuning support page or ask experienced owners on the AMG subreddit.

Conclusion

The AWE Tuning cold air intake is a premium, well-engineered upgrade for the Mercedes-Benz M133 engine. It delivers measurable horsepower and torque gains, sharper throttle response, and a more involving intake sound – all while retaining a clean, OEM+ appearance under the hood. The installation is straightforward for the prepared DIYer, and the cost is modest relative to the performance benefit. When paired with a custom tune, this intake becomes an essential building block for achieving significantly higher power levels safely. For any M133 owner looking to extract more excitement from their car, the AWE intake is a top-tier choice that has earned its reputation in the enthusiast community.