What happens when there is a vacuum leak in an engine?
The engine computer (PCM) calculates how much fuel to inject based on the mass air flow sensor measurements. 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 my PCV leak from the intake manifold?
The hoses and lines that connect the PCV system to the intake manifold are especially prone to failures. This happens because crankcase vapors contain oil, that damages the rubber or plastic, causing hoses and lines to swell and crack.
When to remove an idle air control valve?
Because of the nature of this valve (large air volume processed) it should be serviced when a tune up is performed to remove “coking” which will hinder the valve’s performance. To perform a rough check of the idle air control, remove the valve while reconnecting the wiring harness.
Why does my car idle at high idle?
If this tube becomes loose or broken it can leak un-metered air into the engine effectively causing an unbalance (via the mass air flow MAF sensor) in the computer system which can produce fast or slow idle.
Because of the nature of this valve (large air volume processed) it should be serviced when a tune up is performed to remove “coking” which will hinder the valve’s performance. To perform a rough check of the idle air control, remove the valve while reconnecting the wiring harness.
How can I check the idle air control?
To perform a rough check of the idle air control, remove the valve while reconnecting the wiring harness. While observing the valve with a flashlight, turn the key to the “ON” position, (DO NOT START ENGINE.) the valve should move slightly.
How to troubleshoot an automotive engine high idle?
The troubleshooting procedure for high and low idle conditions are similar, which are included in the following: Step 1 – If the check engine or service engine light soon has illuminated retrieving the diagnostic trouble codes could lead you in the right direction of what the problem is, or is related too.
Can a bad mass air flow sensor trigger a check engine light?
Bad mass air flow sensor with no check engine light? Sometimes a mass airflow sensor can start to fail and even trigger engine error codes such as P0101 and P0102, without triggering a check engine light. There must be a problem with the mass airflow sensor circuit for the check engine light to illuminate.