HELP P0505 & P0511 on New IAC!
 

I've never had trouble fixing anything on this vehicle and not been on the forum in a long time, but this is getting on my nerves LOL. Hoping someone's still out there that can give me some insight. Box has been sitting mostly since I got another vehicle, and it's got 244k on her. Looking to sell it and boom, start it up and the idle is erratic and pops a code, originally just the P0511. Do some googling, try to do a quick fix by shooting some cleaner and WD40 into the IAC opening in the throttle body, seems to help a little but still can't clear the code so I pulled the throttle body and cleaned it, couldn't get the IAC off, the screw heads stripped so did the best I could and buttoned it back up... idles better but now constantly high around 1400 and now I get 2 codes that won't clear P0505 & P0511. OK, so I rip it all back off, drill out the stripped screws and put a new IAC on it thinking that's got to do the trick... now the idle is 1800 - 2000 and still can't get rid of the codes. If I turn on the AC idle is about 1000. If you're wondering, I did replace the TB and IAC gaskets during all this also.

Any help is welcome, it also has a new TPS and MAF and I've tried multiple code clearing and relearning methods, code reader, fuse, battery, to no success. Checked for vacuum leaks but any time I force a leak the idle goes down not up, what should the normal vacuum be at idle, didn't put gauges on it but torque was reporting around 24 at idle. Wondering if in cleaning the old TB it now doesn't close properly? Other than the high idle and codes it's running awesome.

https://cimg0.ibsrv.net/gimg/www.sci...9f086cb5a5.jpg

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https://cimg0.ibsrv.net/gimg/www.sci...217d6ee5ea.jpg
This is all I can find on your 2-Codes P0505 & P0511

Hope it Helps!

MR LUV

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Yep, read those several times but thanks for the reply. IAC is new, so it can't be stuck! The is the MAF, and TPS are also new tho shouldn't be related to the code. All hoses seem to be fine and vacuum is great, maybe even too high hence the very high idle, which makes me wonder about the TB not closing properly after cleaning it. Don't think it's the A/C switch it seems to be functioning just fine. If the ventilation valve mentioned above is the PCV valve, I'll be replacing that cheap item in a day or so. All that's left on the list would be a short in the circuit or the ECM. I found this online and will test the wiring tomorrow but not sure how you test resistance on a harness when you can't reach both ends. https://my.prostreetonline.com/2016/...-xb-iac-valve/ I've also ordered a new VSV but read that should throw a different code if it were the problem, figured what the heck.

While reading the TB removal instructions yet again it dawned on me that just maybe I didn't install the TPS back in correctly so that the throttle valve isn't fully closed at idle position? This would kind of explain what I feel is happening, idle is steady just very high! One more thing for me to check tonight. Man I really hope that's all it is :crazy:

https://cimg0.ibsrv.net/gimg/www.sci...b29827c0b5.jpg

EUREKA!... found the power wire on the IAC harness severed.
https://cimg0.ibsrv.net/gimg/www.sci...8d7d73065a.jpg
Cut IAC Power Wire, caused high idle and P0505 & 0511 codes.

Patched it up, put it back together again, idle came down perfectly, but then got too low, kept bouncing around 450 RPM. Seems somehow in cleaning and/or removing several time the Throttle Stop Screw clearance changed, after getting to operating temperature I adjusted the screw till idle was in the 800 RPM range with no accessories running and tightened back down.
https://cimg0.ibsrv.net/gimg/www.sci...cc2eb03018.jpg
Adjusted this screw to dial in the idle

The box is happily idling again, properly adjusts on cold starts, when the A/C is ON/OFF and all codes cleared! Maybe this will help someone in the future, if you're going to tear into it and to properly troubleshoot always check your wiring to be sure or you'll have to do things multiple times like I did lol. Center Pin on the IAC harness is the power.

https://cimg7.ibsrv.net/gimg/www.sci...c82db682de.jpg

Nice find!

Thank you! This helped me too. I also had a broken wire at the IAC connector that I patched using twist Posi connectors.