Symptom:
    A Passat B4 sedan engine low speed go bad, rapid acceleration is not OK, slow acceleration can, the speed of running up and very good.
    Fault diagnosis analysis and processing:
    Maintenance personnel first check to start the engine, I feel bad start, start after the rapid acceleration speed can not lift up, slow speed can be raised up. Judging by experience should be low oil pressure failure. Out of the road test, low speed driving a meal, as if the feeling of poor fuel supply; speed up after all improved, decided to return to plant to detect electric petrol pump pressure.
    Check the system with hydraulic pressure, normal. And then use the gold Pentium public / Audi - Chinese 1552 car computer decoder to detect the engine to detect the throttle fault code, eliminate the code after the match, the fault code disappears, but the test engine failure still.
    Because the fault is very obvious in the oil field, start difficult, low speed bad, rapid bad, coupled with sometimes can detect the throttle fault code, then decided to replace a new throttle assembly try, put on after the re-match the test , The fault remains the same. Had to restore the old throttle.
    It seems not the oil side of the problems, had to turn to check the circuit, did not find the problem, a similar motorcycle failure, change the ignition coil on the line. After the analysis to determine the ignition coil may be caused by poor work, the car ignition coil and ignition module assembled into a whole, in the engine compartment.
    Troubleshooting
    After the car changes the ignition coil, the engine immediately returned to normal.