What Causes the Jittering During Cold Start of a Volkswagen Sagitar?
1 Answers
Severe jittering during cold start of a Volkswagen Sagitar is generally related to the fuel injection system, ignition system, and idle control system. Below are relevant explanations regarding cold start issues: 1. The primary cause of cold start jittering is low temperature. Insufficient engine temperature requires additional fuel injection during cold starts to meet power demands. 2. Larger spark plug gaps result in weaker ignition energy. Poor fuel atomization at low temperatures demands higher ignition energy. Prolonged vehicle use can enlarge spark plug gaps, reducing ignition energy and consequently affecting performance, leading to vehicle jittering. Additionally, aging ignition coils, high-voltage wires, or electrical leaks can also diminish ignition energy. 3. Inaccurate air-fuel mixture ratios occur in both open-loop and closed-loop control systems. If the vehicle's ECU makes incorrect judgments, errors in controlling the air-fuel mixture and ignition timing through actuators may reduce power output, causing jittering. 4. Carbon deposits. Excessive carbon buildup on valves and intake manifolds can make cold starts difficult, as carbon deposits absorb fuel, leading to ECU miscalculations.