96 Astro Rough idle

Old 07-19-02, 08:14 AM
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96 Astro Rough idle

Hi, I have a 96 chevy astro with 4.3 v6, it idles rough in park and in drive when stoped at lights, runs fine when driving. brought it down for testing awhile ago and they tell me they cant find anything wrong that these astros all have this rough idle, I have changed this list of parts in last 6 months EGR ,PCV, fuel filter,spark plugs,fuel pump, ? I have no idea why it idles so rough.
Old 07-19-02, 10:37 AM
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Bad fuel pressure regulator/CPI injector assembly. Have the fuel pressure checked.

These things are known for bad CPI injectors. Most common cause.
Old 07-19-02, 07:00 PM
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does the check engine light come on ever ?
most higher mileage astro vans do seem to have a bad vibration at idle but this is a gradual problem not something that happened overnight.
they are also known for the egr valve getting stuck open by a piece of carbon and will cause a rough idle but will set the check engine light in most cases.
if you install a fuel pressure guage and start engine when you shut the engine off it should hold the pressure for several minutes if it bleeds down it is likely leaking down under the intake at the injector assembly or the plastic gas lines going to it. causing a rich condition and will usually gas foul one bank of plugs depending on which side of the intake it is leaking on.
Old 07-28-02, 11:00 PM
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I had a 96 Safari, samething , also noticed it seemed to surge when driving on the hiway above 50 mph. From what I read and talking to my mechanic is that the computer leans the fuel mixture out for good fuel economy. This caused the surge or miss type systems. Could also be a computer thing with the idle. It drove me nuts at first but finally got used to it.

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