Why does my MINI Cooper have reduced engine power?

You bought your MINI Cooper because you wanted a fun and fuel-efficient, daily driver. MINI’s offer sporty handling and zippy acceleration, so when your car has reduced engine power, it’s easy to notice. There are several common causes for reduced power in a MINI Cooper, and we are going to cover them here.

Timing chains

Timing chains keep the bottom end of the engine and the cylinder head in time with each other, allowing the valves to open and close at the correct time. Over time, timing chains will stretch out and become loose, resulting in incorrect timing. Behind the wheel, you might notice sluggish acceleration and rough running, as well as a check engine light. When engine timing is incorrect, the valves are not opening and closing at the correct time, causing the engine to run rough.

In the event of total timing chain failure, the pistons and valves can collide with each other. If this happens a complete motor rebuild, or a brand-new engine is required. Do not ignore the symptoms of timing chain problems, it can lead you to very expensive and time-consuming repairs.

Mini chargepipe

Boost leak

Some MINI models are turbocharged. As with most turbocharged vehicles, a boost leak can result in significant power loss. Boost leaks occur when pressurized air between the turbo and intake manifold can escape the system, preventing the engine from making the boost pressure requested by the engine computer. Oftentimes, a boost leak is as simple as a loose hose clamp or disconnected charge pipe, and the problem is fixed once the system is sealed again.

Bad Turbo

Turbos live rough lives. The turbine and compressor wheels spin at extremely high speeds (80,000-200,000 RPMs) nearly constantly. This generates a lot of heat and puts immense stress on the bearings in the turbo. Infrequent oil changes, poor quality oil, hard acceleration on a cold engine, and general wear and tear from thousands of kilometers of driving can lead to turbo failure.

A failed turbo will result in reduced engine power and can omit a whining “spaceship” noise under acceleration. A failed turbo on a MINI will need to be replaced to restore proper operation and engine power.

Mini turbo

Vacuum leak

Your MINI’s engine, and all engines for that matter, are essentially giant air pumps. The intake stroke of the piston creates a vacuum, measure in inches of mercury, as it sucks in a mixture of air and fuel for combustion. The engine computer monitors the amount of air entering the engine with a MAF (mass airflow) or MAP (manifold absolute pressure) sensor and precisely calculates the amount of fuel needed for combustion. A vacuum leak introduces “unmetered” air into the system and can result in the computer not requesting enough fuel.

A vacuum leak can cause a hissing noise, rough running, high idle, and reduced power from the engine.

Limp mode

Limp mode is a safety default your car can enter when it senses something is not right. Typically, limp mode will restrict the speed at which you can drive, the RPMs the engine can rev to, and in the case of automatic transmission vehicles, the gears the car can shift into. There are a wide variety of reasons limp mode can activate.

Bring your MINI to Motor Werke!

If you’ve noticed your MINI doesn’t have the zip it used to, stop in at Motor Werke. Our skilled technicians have a passion for European vehicles, including MINI, and will quickly get to the bottom of the problem. Give us a call or schedule an appointment at our Kelowna repair shop today!