BMW N46 Engine Workshop Manual. Wiring Diagram
BMW N46 B20 / N46 B18 Engine Workshop Manual & Wiring Diagram, detailed repair and maintenance guide for the BMW N46B20 / N46B18 . Includes specifications, step-by-step repair instructions, and electrical diagrams for diagnostics and maintenance. The manual will be useful to owners, auto mechanics, and repair specialists for accurate restoration of engine performance and maintenance of engine reliability.
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| N45/N46 System functions DME ME 9.2/MEV 9.2 | Download |
The main problem areas of N46:
Valvetronic system
Worn eccentric shaft and Valvetronic sensor.
Symptoms: unstable speed, system errors, loss of traction.
Timing chain
Stretched chain and worn tensioner are common, especially after 120-150 thousand km.
Symptoms: metallic noise when starting, valve timing errors.
Oil consumption (increased oil consumption)
Reason: coking of oil scraper caps, wear of piston rings.
The problem can appear already by 100-120 thousand km.
Ignition coils and spark plugs
Bosch/Delphi coils often fail, causing triple and errors in cylinders.
Cooling system
Plastic elements (thermostat housing, pipes) are prone to cracking.
Overheating is possible if not replaced in a timely manner.
Crankcase ventilation (CVV)
The membrane in the ventilation valve breaks over time, which increases oil consumption and causes mixture errors.
Sensors
The camshaft, crankshaft, and mass air flow (MAF) sensors often fail.