The reasons for abnormal noises from the Tiguan's exhaust pipe are as follows: 1. Fuel system issues such as fuel line blockage, poor flow, or rail pressure problems. Abnormal electric fuel pump or fuel filter blockage due to various reasons, obstructed fuel delivery, etc.; abnormal fuel injectors: quality defects, blockages caused by foreign objects, poor sealing, aging O-rings, and other issues can all contribute. 2. Intake or idle control stepper motor issues, dirty or leaking throttle body. Abnormal sensors for atmospheric pressure, temperature, throttle position, etc., leading to incorrect data. 3. Ignition wires aging or cracking, causing leakage or insufficient ignition strength. 4. Cooling issues manifest as difficulty starting, exhaust pipe backfiring upon startup, similar to overly lean air-fuel mixture. 5. Ignition timing (distributor, ignition coil, etc.) too late: delayed ignition causes incomplete combustion of the air-fuel mixture. Recommendation: Rotate the distributor housing counter to the rotation direction of the rotor by an appropriate angle to resolve the issue. Misalignment: possibly due to incorrect or misplaced ignition wires, causing individual or multiple cylinders to malfunction or not work. 6. Distributor issues such as stuck centrifugal weights or other internal faults. Ignition timing not advanced properly, causing delayed ignition and exhaust pipe backfiring. 7. Spark plug issues: decreased ignition efficiency leads to unburned mixture entering the exhaust pipe and causing backfiring.
