What causes a vacuum leak in a MAF system?
This kind of constant leak in a MAF system is the classic “vacuum leak” where a gasket, coupler or piece of tubing in between the MAF and the engine does not seal properly. In this case, air can enter the engine without passing through the MAF.
What happens when there is a vacuum leak?
If there is a vacuum leak anywhere between the engine and the mass air flow sensor, it causes “unmetered” air to enter the system. This causes the actual air flow to be higher than the mass air flow sensor measures.
What causes a mass air flow sensor to fail?
Most of the time, a mass air flow sensor will fail because it loses its sensitivity over time due to a build up of dirt or grease. It will also be affected by the high temperature of the engine. Due to its location in the engine, the mass airflow sensor can regularly be exposed to a wide range of temperatures from freezing to well over 100 degrees.
What does ECM do in a vacuum leak?
Using the manifold absolute pressure (MAP) sensor or mass air flow (MAF) sensor, among others, the ECM modulates fuel injector pulse, spark timing, and valve timing. If there is a vacuum leak, the ECM may be unable to compensate.
What causes a vacuum leak on a manifold?
Vacuum leaks on individual cylinders commonly occur around intake port gaskets or vacuum hose connections. Insufficient valve lash, a broken piston ring or a leaking cylinder head gasket can cause a partial loss of compression. Depending on where the vacuum leak is on the manifold, it can generate random or specific cylinder misfire codes.
If there is a vacuum leak anywhere between the engine and the mass air flow sensor, it causes “unmetered” air to enter the system. This causes the actual air flow to be higher than the mass air flow sensor measures.
Why does a vacuum leak cause a check engine light?
Because, it allows “unmetered” air to enter the engine and upset the air/fuel ratio. Also, a vacuum leak can trigger a “check engine” light. Because, the fuel system is running too “lean,” meaning it has a greater mix of air than is ideal. For most people a vacuum leak repair is not that hard to do.
Where does the vacuum leak sound come from?
Often, a vacuum leak makes an audible hissing sound, which makes it easy to find; other times, though, you won’t hear anything. Vacuum leaks can develop in many locations; including the intake manifold, throttle body, emissions system and power brake booster.