Oldsmobile Silhouette RPM Drops Low At Idle

2001 Oldsmobile Silhouette 3.4 V6. Replaced fuel Pressure Regulator, thermostat at 200,000 miles, new spark plugs at 190,000 Miles, fuel pump at 175,000. Just started to research this problem and have not found any real answers. My van dies out most oif the time.

Question: Car Starts then will die. If started and the throttle is slightly pressed down it will stay running. If I release on the pedal the RPM drops to 500 then lower and dies. While driving and coming to a stoplight at 20mph the RPM again will drop below 500 and die. Slowly releasing the pedal below 1000 rpm and above 500 rpm. Trying to hold it steady the idle will start to search and surge. With the amount of miles on my van I am guessing it might be the TPI or some other electronic part. Any help would be great.

oldsmobile silhouette

ANSWER:

Thank you for the tip / donation. A couple of things to look for. Make sure the air duct between the air filter and the engine throttle body are tight. If loose, this can cause your problem. Also check the breather tube from the top of the duct to were it attach to the top of the rear valve cover under the ignition coils assembly. Never real tight in the valve cover, but snug. Also check for vacuum leaks.

These things could cause this problem, as well as possibly setting a lean oxygen sensor code. The other possibility is the Idle Air Control (IAC) valve is carboned up. It is on the back side if the throttle body- -4 wire connector, 2 TORX screws hold it on. As the name states, it controls the idle speed. These almost never give a check engine light or store a trouble code.

Suggest remove the valve and clean carbon from valve and its bore, as well as cleaning the throttle body plate and bore. Do not move the IAC valve in and out as this may cause it to bind and not function, just clean it. Low speed coolant fan wont come on until about 226 degrees.I will send a resistance chart in a few moments for the coolant sensor.


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