- Use unleaded petrol only.
- When installing the catalytic converter later, fill up with unleaded fuel at least twice before installing it. In addition, on engines that require super gasoline, the ignition should be set to a later time, since unleaded super gasoline has an octane rating of only 95. How many degrees to set the ignition depends on the model.
- It is forbidden to start the engine by towing or "push starting". Unburned fuel would cause overheating when ignited in the catalytic converter. If the battery is discharged, do not start the engine from the battery of another car.
- Avoid frequent cold engine starts in a row. In this case, unburned fuel accumulates in the catalytic converter, and when heated, it burns out and the catalytic converter fails.
- If you have difficulty starting the engine, do not turn on the starter for a long time unless necessary. When the starter is running, fuel is constantly injected. Determine and eliminate the source of the malfunction.
- If ignition problems occur, remove the fuel pump relay connector until the cause is determined. This prevents fuel injection when starting the engine. The fuel pump relay is located in the front passenger's feet in front of the front pillar under the side trim.
- Do not check for spark with the spark plug caps removed.
- Comparison of cylinders cannot be performed (balance test) by turning off the ignition of one of the cylinders. When turning off the ignition of one of the cylinders - even with the help of an engine tester - unburned fuel gets into the catalytic converter.
- If ignition failures occur, avoid running the engine at high speeds and immediately eliminate the malfunction.
- Install only spark plugs recommended for vehicles with a catalytic converter.
(The original text of the article is available on the resource BMWMAN)