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How's it going guys.

Alright, I've been on this forum from top to bottom read and diagnosed everything within my capabilities.

What I need to know is what is the solution to a p0505 code.

My car: 99 civic si, b16a2.
Installed mods: aem short ram, yonaka header to a straight pipe and yonaka catback. (I had an aem v2 previously installed until I move to flordia, can't risk hydrolock). Also have a walbro 255 fuel pump installed when the stock one went out.

new plugs, wires, dizzy, rotor, had a fuel injector clean, new cam shaft oil seal (skunk 2) new distributor o ring. A few other seals.

Ok here's the problem like on other threads.

From the start: I start the car it idles at 1200rpm, when at running temp idles down to 1000rpm. Fine. Should be lower but it'll do. Im trying to make this clear cut and get a simple answer. Ok I get in my start it up and drive until temp is at operating temperature, come to a stop light and wait a few seconds and the CEL comes on I get the p0505. When trying to step on the gas the rpms will bounce between 1300-1500 until code is cleared (I drive with a pocket scanner plugged in to clear it while driving). Clear the code and im good until I shut the car off and start driving again. The cycle repeats.

I used my multimeter and checked the map sensor voltage, tps, iacv. Everything checks out.

Now I replaced my iacv 4 times already thinking it could of been a bad part off the shelf. I got it from advanced auto. It's almost identical to original its also a denso part.

I did an idle relearn twice to no beneficial result. I also covered the little hole in the throttle body and the car bogs down, pulled the plug out of the iacv when running rpms dont increase until I plug it back it. I've sprayed carb cleaner all over the engine bay looking for vacuum leaks, none. Hoses are great. I'm clueless as to what could be next. Ive read the ecu is going bad? Idk though.

Can anyone help give me a clear answer these forums get so cluttered with other questions within the OP.

Also my cruise control went out idk what that has to do with anything worked fine one day and then it doesnt. I checked the fuses and the connections on the clutch and brake all good and working properly. Just no cruise control lights come on and everything, just doesn't engage.

Thanks in advanced to whoever can help me figure this out.

Oh also replaced the air intake temp sensor and pcv valve

 
Rep Power: 518

P0505 generally means the computer can't get the idle speed down to it's liking. It doesn't have complete control of the idle speed.


High idle AND cruise quit? Could it be the same as this post?:

https://www.civicforums.com/forums/1...know-what.html

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Does the IAC get good and hot with coolant flow?

Crank the IAB screw (the big one on the throttle body, if equipped) down a turn or two?

 
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Right the iac gets good and hot, I did check the whole cruise control system today and didn't notice anything connecting to the intake manifold, ill have to double check that. Also its a b16a2, I was told by a friends mechanic that there is no idle control screw.. could be wrong I've personally looked and never seen one. Could of definitely overlooked it. Thanks for the help.

If anyone else has any input would greatly appreciate it.

 
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It was exactly that.... I always seen that hose disconnected though. Car is in the garage ill confirm if it was it tomorrow when I pull it out. Thank you.

 
Rep Power: 518

What, the cruise vacuum hose fell off?

 
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Yes the vacuum line fell off from behind the intake manifold

 
Rep Power: 518

Cool beans

 
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Ill start it up tomorrow to really see. I was on my last little hope. I was going to pull 10k and do a b20/b16 swap boosted lol.