Hello everyone, I recently bought a 99 Honda Accord 2.3l F23A manual with 264k miles. I didn’t care about the condition at the time as it was my first manual car and I was ecstatic to learn and drive one. Unfortunately yet inevitably I am facing the repercussions, I work on it myself and have done the following;
•Spark plugs and Coils/Wires
•Valve Cover Gasket
•Motor and Transmission Mounts
•Idle Air Control Valve
•EGR Valve

I have more parts on the way such as drive belt, power steering belt, distributor, and fuel injectors and plan on installing them myself.

The most recent thing I have done on my car was the Idle Air Control Valve and I took off the entire upper intake manifold off and did my best to clean the egr passageway, throttle body, and inside the upper air intake manifold (extreme grime and buildup) as I didn’t want to risk trying to clean the lower intake manifold and getting grime all in the engine. Anyways I installed the new IAC valve, put in a new gasket, double checked to make sure I plugged everything back in, and went to start the car and it started but immediately died. I can keep the engine alive if i use the throttle and it actually gets better once I start driving, and next time I come to a stop it has a low idle (around 500rpms even with cold engine) but every time on startup it either dies or tries to die and sits at around 50-100 rpm’s. I’ve just recently gotten the CEL and the P0505 code popped up which everywhere I see, means the Idle Air Control Valve is faulty.

Please help any information will be helpful and much appreciated. Keep in mind It happened only after I took apart pretty much my whole air intake system, I triple checked to make sure everything was plugged in, wires, hoses, etc. and put in a brand new gasket. the only things I can think of is I either damaged hoses along the way and now have a leak, Wiring or Connectors are toast (264k mile engine) Or the IAC valve I got is a dud.

 

Why did you replace the IACV?

 

Because the car was idling low prior and I had no clue when it was last replaced, only a $30 dollar part so i decided replace it instead of trying to just clean it.

 

Not a good idea. Cheap replacement parts are rarely as good as an OEM one.

 

Haha, thanks luke! 👍 Hopefully this turbo kit I got off of Temu treats me a bit better. 😀

 

I’d look and listen for a vacuum leak around your intake manifold I had done my iac and although it didn’t fix my idle I still had a leak making it worse.

 

Does sound like a vacuum leak. Check everything you took off that is part of the intake system. EGR Valve not seated properly, or without a good gasket. is a vacuum leak every time. Same with IACV. If no vacuum leak, maybe unplug the electrical wire on the IACV while the engine is running. The idle should go very low, but engine should keep running. If you took off the throttle body, reinstalling it and its gasket requires precise work. If you do have a vacuum leak in that area, you have your work cut out for you. If all else fails, put the old IACV back on as previously suggested, or find a seller on eBay or other that sells refurbished Denso IACV's and has good ratings. The cheap no name or unknown name "new" ones are risky.