Mercedes CLK Engine Trouble Resolved

It sounds like you are experiencing a few issues that could be related to your injection system. The symptoms you describe—increased fuel consumption, reduced engine power, stalling, and smoke—do suggest a problem with air or fuel delivery. A defective cable or plug connection is a plausible cause. Before jumping to conclusions, it would be beneficial to check the mass air flow (MAF) sensor. A faulty MAF sensor can cause the engine to miscalculate the amount of fuel needed, leading to a rich or lean mixture, which in turn causes those symptoms. Has the MAF sensor been checked or cleaned recently?

Thank you for your reply. I have not checked the MAF sensor. Can you please explain how that could impact the engine's power? I admit that I am not very knowledgeable about these things.

Certainly. The MAF sensor measures the amount of air entering the engine. This data is crucial for the engine control unit (ECU) to calculate the correct amount of fuel to inject. If the MAF sensor is sending incorrect data – for instance, reporting less air than is actually entering – the ECU will inject too much fuel, leading to a rich mixture. This can cause reduced power, poor fuel economy, stalling, and smoke. Given your symptoms, it's worth investigating. However, considering the potential complexity and your description of the symptoms, it might be wise to have a workshop take a look. They can perform a proper diagnostic scan and pinpoint the issue, potentially saving you time and money in the long run. The cost should be around 95€.

Thank you for your detailed explanation and advice. I took your advice and brought the car to a workshop. As you suggested, they ran diagnostics and found a faulty connection in the injection system. They repaired the connection for 95€. The car now runs perfectly, and the engine power is back. I appreciate your help!