Pontiac Grand am 98 Idle high

deb963April 2, 2013

When i start my car my Idle goes high for about 10 seconds then drops back to normal.... I can drive it cause the idle stays normal...It justs give me a a high idle when started... Please Help!

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jemdandy

That may be normal. Just how high is it? In cold weather, it might go to 1200 rpm at first start and then pull back to 900 rpm in the next few seconds. After a few minutes, it should settle to about 700 rpm.

If the engine hits 2000 rpm on startup and is too slow in reducing speed, it needs attention. This assumes it was started with your foot off the accelerator and allowing the engine controller to control the process.

Also, you may note this happening in cold weather: The idle speed increases slightly when the gear selector is moved from park or neutral to any gear. What's happening is this (for automatic transmissions): When the transmission is put into gear from neutral, the engine controller increases the idle speed a bit to compensate for the extra drag put on by the transmission. If the transmission is a little slow in engaging, the engine will speed up and then drop back in rpm as the transmission cluthes fully engage. This effect is less noticable after the transmission fluid warms and the shift from neutral to a gear quickens. The effect is more noticeable with transmissions that have accumulated wear on shifting valve seals and clutch facings.

    Bookmark   April 4, 2013 at 10:58PM
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