Chasing an IACV Issue

CDsDontBurn

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As the title says, I'm chasing an IACV issue. I have already:
  • Replaced IAC valve with new
  • Fixed a leak at the plate where brake booster hose meets intake manifold
  • Ensured IM is torqued properly
Despite having done the above, I still have high RPMs (stopped and in gear, like at a red light) and RPM bounce while in Park or neutral.

What else can I check and more importantly, HOW can I check or test other potential failure points which would allow extra air entering the intake system?
 

Sil2DrV6

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Not so sure if the symptom I had is exactly the same as yours, but I remember my RPM used to fluctuate a little bit, while at a stop light. When I searched for a solution up here, I ended up suspecting the air leakage by the stock air intake box. I had one of the corner sections, where the top box meats the bottom box, was cracked a bit, and loosing air. I duct taped the cracked section to make sure it was meeting firmly, and the RPM fluctuation was completely gone.

I hope yours is a simple cause like mine. Good luck with the solution!
 

CDsDontBurn

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I did the air silencer delete mod years ago and this issue has only popped up within the last two years. You reminded me that my intake tube from the box to the TB was cracked, but I replaced that as well.

I've recently learned about a smoke test, but I don't have a smoke machine. If I were a smoker, I'd smoke it myself, lol. However, I'm not a smoker and the couple of times I have tried smoking all I've done was cough and cough on that first hit. Nothing that would help me be a "biological smoke machine", lol.

Since I'm in California, I need to do smog check this year (every other year thing) and it won't pass with a CEL turned on so I need to get this fixed.
 
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