Rep Power: 0

Hey Everyone
I’ve been chasing a P0505 Idle Air Control code on my 2000 Civic EX (D16Y8). I ran a smoke test and the only place smoke comes out is along the entire top edge where the intake manifold meets the cylinder head (right where the gasket seals). It’s not coming from hoses, the throttle body gasket, or the IACV itself — it’s literally the gasket line on the top side

So far I’ve,

• Replaced the intake manifold gasket (torqued bolts properly, surfaces cleaned).
  
• Replaced the throttle body gasket as well just to rule it out.
  
• Ran the smoke test again → still leaks right away along the same spot. CEL comes back within 5-10 minutes
  

Symptoms:

• With the CEL cleared, car drives okay but feels kind of “rough” or like it’s not breathing right.
  
• Once CEL sets, idle surges up and down.
  
• Bogs and Hesitates to drive when CEL is on
  

Has anyone run into this before where a new gasket still doesn’t fix the leak?

What’s the best next step? Machine/resurface the intake manifold? Try OEM gasket instead of aftermarket?

What Should I do?

Appreciate any advice — I just want to get rid of this leak and the P0505 for good.

 
Rep Power: 222

Check the intake manifold and head surfaces for flatness, try with an oem gasket