How to fix BMW slow acceleration?

Some customers feedback their cars won’t accelerate when pressing the gas pedal, and we just had such case three weeks ago and will share in this post. Check below details.

Vehicle information

Model: BMW 320i

Engine: N46

Year: 2011


Fault symptom

During the test run, the speed cannot be improved after 80Km / h, the acceleration was slow, and appear drivetrain malfunction.


Repair process

1. Connect scanner with car, no fault code read.

2. Possible causes:

 A.The engine room has a thick ash layer, which means that the driving environment is harsh and may cause the air filter element to be blocked;

 B.The fuel quality is not good, resulting in blockage of the fuel injection nozzle or three-way catalytic blockage;

 C. Individual sensor failures make the vehicle enter emergency mode, speed or limit;

 D.Large vehicle mileage, carbon deposits in the intake duct, insufficient air intake, and insufficient combustion;

3. Check that the air filter element is really dirty, and the throttle valve is also dirty. Clean the throttle valve and replace the air filter element. Then test driving, the acceleration is better, but still feel that the acceleration is weak. Remove the front oxygen sensor and check the three-way catalytic converter with an endoscope, found it’s a little blocked.


4. After cleaning with a three-way catalytic cleaning machine, the attached crops are less.

5. Start to test driving, the acceleration tends to be normal, and the diagnose computer detects no relevant fault codes. After that, it is recommended that the customer remove the ternary catalyst for water gun flushing. After the flush, the test driving is normal. The car owner feedback the acceleration is good after two weeks of driving.


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