BMW E36 mass air flow sensor and vacuum leak
E36 idle fluctuates: how do I find a vacuum leak?
With the engine running, carefully spray a flammable spray, such as brake cleaner or starter fluid, on the intake manifold joints and hoses. If the revs change when the spray hits a spot, the leak is there.
Where is an E36 vacuum leak usually?
Typical spots are the rubber boot leading from the mass air flow sensor and perished hoses. Cracks in the boot may be visible only against the light. A leak raises consumption and weakens acceleration, and replacing an old hose can even out the idle.
How do I clean and test the E36 mass air flow sensor (MAF)?
The sensor must not be cleaned with solvents, only with a cleaner made for the purpose. The cover is not worth opening, because there is nothing adjustable inside. Quick test: unplug the connector while the engine is running. If the running does not change, the sensor is not working. Unplugging leaves a fault code in memory.