BMW E36 spark plugs and ignition coils
Which spark plugs belong in an E36?
In the M50 engine the original is Bosch F7LDCR or NGK BKR6EK. The BMW part numbers are Bosch 12129063428 and NGK 12129064619. If the engine runs well, keep the same brand and type, because changing can cause running problems.
How often are E36 spark plugs replaced?
The interval depends on the plugs and the model. With BMW's own plugs the interval is usually 50000 or even 100000 km. Worn or loose plugs can cause idle hesitation, so replace them as a set and also check the earth straps.
How do I find a faulty ignition coil?
Each cylinder has its own coil. Remove the coils one at a time and listen for a change in running. Hairline cracks or torn rubber on the coil cause hesitation and sputtering. A good coil has a primary resistance of 0.5 ohms and a secondary resistance of 5000-6000 ohms.
What does oil or moisture in the spark plug wells tell me?
A wet plug points to a coil fault. If there is oil in the plug wells, the valve cover gasket is leaking. Replace the gasket first and only then assess whether new coils are needed.