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Stumbling idle

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#1
BlueJay73

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  • Location:Baton Rouge, La.
  • Car Year:1999
  • Car Number:27

Any of you knowledgeable minds out there have any ideas why my '99 has acquired a stumbling idle?

It runs smooth and seemingly fine at higher RPM's, not missing or anything.

Do Idle air control valves go bad? I checked all the electrical connectors and rubber hoses in the area and they all seem secure. Anyone know any likely culprits to look for?

 

Thanks,

Jim



#2
FTodaro

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Yes the AICV goes bad and it also can get dirty. Try cleaning it first then replace. Also check TPS.


Frank
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#3
tynor

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I had a chronic problem with my '99 -- very rough idle when cold, but once it came up to temperature, would idle normally.  We tried everything - cleaned the IAC, cleaned the throttle body, replaced both with known good spares, replaced the TPS.  Nothing seemed to work.  Disconnecting the TPS would solve the problem.   

 

I had to  have the engine torn down for a different reason and in the process, Mike Rossini recommended replacing the C valve (not PCV).  I've not had idle problems since.  I can't be sure the new C valve was the cause of the fix, but it may have been.   

 

I've tried to find the valve on a parts diagram and can't find it -- as I recall it lives under the intake manifold on the passenger side of the engine.


Steve Tynor

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#4
Steve Scheifler

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Is that the little green & white 1-way in the middle of a vacuum line? If so, when it fails you may also have faulty actuation of the intake butterfies. The actuator will still move them but not hold them correctly..
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#5
tynor

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Is that the little green & white 1-way in the middle of a vacuum line? If so, when it fails you may also have faulty actuation of the intake butterfies. The actuator will still move them but not hold them correctly..

 

I believe so, but I never actually saw the valve - Mike described it to me and pointed in its general direction, but I don't believe I ever actually saw the part.


Steve Tynor

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#6
Steve Scheifler

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I believe there are at least two of them but the one buried about the middle of the intake near the injectors sounds like what you described. You can't even see it without pulling the top half of the intake.
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