Engine Performance problem
2004 Oldsmobile Alero 6 cyl Front Wheel Drive Automatic 120000 miles
When I initially start the car, the car idles at about about 1500 rpm while it warms up. At the point the vehicle should idle down, it either continues to idle at 1500 rpms or it will idle up with in a few seconds to about 2000 rpm. It will sit and idle at that speed while in park for an extended period of time. When dropping it into reverse it will idle down to about 750 rpms, but almost kills the engine because it drops to such a low idle speed compared ot the 2000 rpm. When you put it back in drive, nuetral, or park, the idle speed goes back up to the 1500 to 2000 rpm range. As the car idles at that high rate, it pulls the car into doing anywhere between 25 and 40 mph. The car will drive itself at that speed while hardly having to give it any gas. This makes braking more difficult, but the vehicle can be stopped and held there.
In most cases, if you drive the car for a few blocks or a mile, shut if off at a stop sign or a stop light and restart it, it will start up and idle at 750 rpms and will idle normally. Starting and restarting without driving it does not generally bring the idle down. Any suggestion on the problem?
Need to take a look at the IAC idle air control system.
Have a system diagnosis done this adjusts idle speed via PCM ie computer. The valve maybe receiving idle up input due to another component.
Does the check engine light come on?
Hope this helps
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