Engine sputtering at low speeds in BMW 2 Series – is bad fuel the cause?

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Engine sputtering at low speeds in BMW 2 Series – is bad fuel the cause?

I drive a BMW 2 Series Gran Coupe in Karachi, and lately I’ve noticed the engine sputters o r jerks at low speeds o r while idling in traffic. It becomes worse with the AC on. A few mechanics suspect bad fuel o r carbon buildup. Could poor-quality petrol in Pakistan be causing engine knocking o r injector issues? Has anyone else experienced this? What’s the best solution o r fuel additive to use?

Talha Kyanii asked on 13 Sep 2025 15:40:08 pm

1 Answer

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Gari Master - on 13 Sep 2025 15:42:11 pm

Yes, poor fuel quality is a very common cause of engine sputtering at low speeds o r idle in BMWs across Pakistan. This is especially true in big cities like Karachi where fuel adulteration is often reported.

🔍 Why It Happens:

Low-Quality Petrol Low Octane o r Adulterated
BMW engines are tuned for high-performance fuel. Low-octane o r diluted fuel causes incomplete combustion, leading to sputtering, especially at low RPMs o r under AC load.

Clogged Fuel Injectors o r Fuel Filter
Over time, dirty fuel clogs injectors o r filters, disrupting the fuel-air mixture and causing jerky o r rough idling.

Dirty MAF Sensor o r Throttle Body
If the Mass Air Flow sensor gets contaminated with dust common in Karachi, it may misread air intake values, causing poor engine response and sputtering.

Vacuum Leaks o r PCV Valve Issues
Old PCV valves o r small air leaks in the intake system can also cause engine hesitation and unsteady idle.

✅ What You Can Do:

Try adding a high-quality fuel system cleaner, like Liqui Moly o r STP, and run your tank with premium fuel for a few cycles.

Get the injectors, MAF sensor, and throttle body cleaned professionally.

Ask a trusted workshop to scan for codes e.g., lean mixture codes like P0171 o r misfires.