This kind of stalling problem often means the engine is not getting enough fuel and/or too much air. A cold engine needs a fairly rich fuel mixture to start, and to idle smoothly while it warms up. Any of the following could cause or contribute to this kind of stalling problem:
First make sure bad gas is not causing the problem.
Add dry gas and fill up the tank with next higher octane.
Check for vacuum leak around the intake manifold
gasket or throttle body, leaks around the PCV valve and EGR valve
Check for dirty or defective airflow sensor. A sensor that has been contaminated by fuel varnish or dirt will under report airflow and be slow to react to changes in airflow. This can upset the air/fuel mixture causing idle, stalling and hesitation problems. Cleaning the airflow sensor wire with aerosol electronics cleaner can often restore normal operation and cure the problem.
Check for a defective idle speed control
system. Idle speed on a fuel injected engine is controlled by allowing a small amount of air to bypass the throttle. If the idle air bypass circuit is plugged with dirt or fuel varnish, or the solenoid valve is sticking or broken, the engine may not get enough air to idle normally causing it to stall. Cleaning the idle air bypass circuit in the throttle body with aerosol throttle cleaner will often remove the gunk and solve your stalling problem. If a good soaking with cleaner fails to fix the stalling problem, check the wiring connector
. It might be loose or corroded. If no wiring faults are found, you may have to replace the idle speed control
Also, when the engine is running slowly, there is less momentum to keep it going, so a bad misfire may cause it to stall. If the spark plugs have not been changed in a long time, a new set of plugs and/or plug wires can restore a good hot spark and eliminate the misfire. A weak ignition coil or a faulty crankshaft position sensor may also cause a stalling problem.
Saturday, January 16th, 2010 AT 2:10 PM