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P0506 Idle Air Ctrl Sys and Failed smog test
Dear All,
I hooked up my code reader which revealed the following code: P0506, idle air control system failure. The engine has a stable idle when cold, ~800, when it warms up it goes a bit over 1000 and fluctuates between ~1100-1200. I`ll look into this tomorrow but I thought I ask the Community first if there`s anything obvious to look at with these symptoms. Intake plenums and throttle housing are cleaned, the whole engine has just been freshly put together. Not sure if related, but the car failed the smog test yesterday. Emission is fine, I was told the reader could not reveal the fault code history because the battery was disconnected for too long, for 13 years actually. So I was told to put a couple hundred miles into the car and go back and it would pass... Thanks for any insight. |
P0506 code is for idle speed too low, common issues is the IAC valve sticking or a blocked air filter element.
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That does not sound correct.
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Update: I fixed the code issue, it was indeed the IAC valve, thanks for the suggestion. It wasn`t really dirty, but I think it was stuck. I disassembled and cleaned it out and now idling is stable and the code s gone.
http://986forum.com/forums/uploads02...1604258790.jpg I made a video of the intakes expanding, uploaded it here: https://www.youtube.com/watch?v=8C2ZBcO4WZY&feature=youtu.be Perhaps the new rings need to wear in and not seating perfectly yet..:confused: |
My 98 "breathes" exactly as yours does. At first I was concerned until I realized what is happening. With throttle closed and max vacuum in intake plenums, everything is drawn together. When the throttle is opened intake manifold vacuum drops and the intake manifolds relax appearing to expand. I may be wrong.
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Dealing with the same issue. I cleaned my TB and ICV with cleaner. The idle issues persisted, then I went through 4 aftermarket ones, one of which wasn't too bad but the rest either didn't fit or wouldn't run. I finally got fed up and put the original Bosch unit in after fill/drain with rubbing alcohol then seafoam. Still having the same symptoms. Would opening it up and cleaning it do the truck, or should I get another new one?
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