Audi A1 Stalling & Jerking Points to Rich Fuel Mix

Having dealt with nearly identical symptoms on my Audi A3 2018, this strongly points to a fuel injection system issue. The check engine light repeatedly illuminated, and the engine showed the same behavior, rough idle, poor acceleration, and inconsistent power delivery. After proper diagnosis, the problem was traced to a defective fuel injector. The faulty injector was causing uneven fuel distribution, leading to a rich fuel mixture. While the oxygen sensor and throttle body were initially suspected, testing revealed the injector was not maintaining proper spray patterns. This is considered a serious issue that requires prompt attention, as continued operation can damage the catalytic converter due to unburned fuel. The symptoms worsen over time, and waiting typically leads to more extensive repairs. The correct diagnosis requires specific diagnostic equipment to test injector spray patterns and fuel pressure. A mechanic should perform: Fuel pressure testing, Individual injector electrical testing, Spray pattern analysis, Full system scan for fuel trim values The repair involves removing and either cleaning or replacing the affected injector, followed by a complete fuel system cleaning to prevent future issues.

Thanks for the detailed breakdown of the fuel injector problem. Similar situation with my A1, though initially the mechanic focused on the throttle body and oxygen sensor before finding the real culprit. Mind sharing how much the injector replacement and system cleaning cost you? Also curious if youve had any issues since the repair, especially with the check engine light?

Since replacing the faulty injector, my A3 has been running perfectly with no check engine light issues. The repair cost came to 515 Euro total, which covered the new injector and a thorough fuel system cleaning. The air-fuel ratio is now spot on, and the engine runs smoothly at all speeds. The mechanic confirmed it was definitely a defective injection valve causing the rich mixture problem. They also checked the intake manifold and spark plugs while doing the work, but those components were fine. It was worth every cent to have it properly diagnosed and fixed rather than continuing to chase other potential causes. The car now accelerates cleanly with no hesitation or rough running. If your symptoms match what I experienced, getting the injector replaced should solve your issues completely.

After reading through the replies, I finally got my A1 properly diagnosed and fixed. The mass airflow sensor readings were showing normal, but the mechanic found two faulty fuel injectors causing the rich mixture. Total repair came to 780 Euro including parts and labor. The mechanic showed me the old injectors, they were badly clogged and not spraying properly. This explained the rough idle and power issues. They also did a complete fuel system cleaning while everything was apart. Been driving for two weeks now and the difference is night and day. No more check engine light, smooth acceleration, and proper idle. The air-fuel ratio is now correct according to the scan tool readings. Really glad I pushed for a thorough diagnosis instead of just accepting the initial throttle body theory.