Why does the old Jetta have trouble accelerating when cold but runs normally when warm?
2 Answers
There may be an issue with the throttle. Below is relevant information: 1. Overview: Jetta is an automobile brand under FAW-Volkswagen Automotive Company, a joint venture of the German Volkswagen Group in China. Its first product, the Jetta-MK1, was launched in Europe in 1979. 2. Other: On February 26, 2019, Volkswagen's first-ever sub-brand, the Jetta brand, was officially unveiled at Volkswagen's headquarters in Wolfsburg, Germany. This new brand is scheduled to enter the Chinese market in March of this year, becoming the third brand under the long-term cooperation between Volkswagen and FAW-Volkswagen.
I've encountered this issue quite a few times. The old Jetta struggles to accelerate during cold starts, but runs smoothly once warmed up—it's quite a headache. When the engine is cold, possible causes include: an aging fuel pump causing unstable fuel supply, excessive carbon buildup in the injectors leading to poor atomization and affecting fuel injection volume; a faulty coolant temperature sensor misleading the ECU into not providing sufficient fuel; or a dirty throttle body in the intake system restricting airflow. Older cars are prone to such problems. I recommend starting with simple checks—clean the air filter and replace the fuel filter. If that doesn't help, visit a professional shop to test the sensors and circuits. Regular maintenance and timely carbon cleaning can prevent this. In short, poor acceleration when cold is dangerous—prioritize repairs for safety.
