P0506 (Idle Control System RPM Lower Than Expected) - Chevy Colorado & GMC Canyon
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post #1 of 21 (permalink) Old 10-22-2008, 01:33 AM Thread Starter
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P0506 (Idle Control System RPM Lower Than Expected)

Anyone experienced this before ? The truck is throwing the code, even after clearing it twice. Seems to idle absolutely normally, and a friend of mine told me that it might be a problem with my intake air control valve, although he was unsure if our trucks are even equipped with one of them.

Only other things that i thought of was to clean the throttle body and the mass airflow sensor... and also i need to change the oil.

...just hoping that someone could point me in the right direction with this problem, and yes i know i should take it to the dealership, but i don't have a warranty

thanks in advance for any thoughts

-jason

http://www.canada355.com/
2005 Black LS Extd. I5 Z85/2WD
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post #2 of 21 (permalink) Old 10-22-2008, 02:36 AM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

Definitely clean the throttle body and MAF sensor. Then see if it still gives you the code after you clear it.


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post #3 of 21 (permalink) Old 10-23-2008, 07:37 PM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

Yea, my 2004 displayed the code this morning. Cool front came through texas this morning with some moisture. Autozone computer indicated, 1-vacumn leak on engine, 2-dirty throttle body, 3-iac motor defective, 4-poor electrical connection to te IAC valve. What the heck is a IAC motor?

I gonna assume cool front for now, cleared code and will see what happens in the morning.

Any other ideas?
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post #4 of 21 (permalink) Old 10-23-2008, 08:37 PM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

IAC stands for "Idle Air Control". I don't think our colorado's have an IAC motor. So you can eliminate #'s 3 and 4 in your post.
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post #5 of 21 (permalink) Old 10-24-2008, 12:51 AM Thread Starter
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Re: P0506 (Idle Control System RPM Lower Than Expected)

yep, first thing i heard to check for was the vacuum hoses.. and as we all know there are plenty of those, and it makes it difficult to pinpoint a leak unless you have a smoke machine. the least you can do is to check all the connections and visually inspect the hoses, worm clamps etc.

..i haven't had a chance to do anything yet, except reset the CEL... which has now came on again after a couple more warm up cycles.
I can notice the RMPs struggling a little bit now that i'm paying attention. never seems to dip under 500 though, but with my exhaust i can definitely notice a change of tone while idling

either way, when i have time.. i will clean the MAF sensor, throttle body, replace spark plugs, change fuel filter, and change my oil.

a combination of all these should eliminate the problem unless its a vacuum hose leaking... in which case it's most likely off to the mechanic.

also, i'm not sure if we have a IAC motor or not, but isn't the throttle plate in our throttle body controlled by some kind of motor?? possibly a malfunction with that... (shot in the dark)

-jason

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post #6 of 21 (permalink) Old 10-24-2008, 11:27 PM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

Actually, our engines don't have a lot of vacuum hoses. Check every connection on the air intake between the MAF sensor and the throttlebody. Spray some carb cleaner on each connection and see if the rpms change. If you still have the factory intake, check the plastic ducts and resonator for cracks. Don't forget to check the PCV hose from the top of the valve cover to the bottom of the resonator. Mine is showing signs of dry rot.

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post #7 of 21 (permalink) Old 10-27-2008, 09:59 AM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

Thanks for the threads. This site is awesome. Cleaned the MAF sensor and throuttle body butterfly, gained appx 100 RPM at warm idle and check engine light has not reappeared. For now anyway.
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post #8 of 21 (permalink) Old 10-27-2008, 08:07 PM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

I am having the same p0506 code with the check engine light. How would I go about cleaning the MAF sensor and the throttle body butterfly? At times I do notice a drop and bounce in rpms when idling.
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post #9 of 21 (permalink) Old 10-27-2008, 08:37 PM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

Here's the how-to for the throttle body: http://www.coloradofans.com/forums/view ... =8&t=54407

For the MAF sensor, pick up a can of CRC MAF Sensor Cleaner at a local auto parts store



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post #10 of 21 (permalink) Old 10-29-2008, 10:08 PM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

Thank You!!
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post #11 of 21 (permalink) Old 11-02-2008, 03:40 PM Thread Starter
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Re: P0506 (Idle Control System RPM Lower Than Expected)

Hey guys, finally got around to cleaning my throttle body and MAF sensor last week... No more CEL and it seems to idle steadily now. I also noticed that when shifting gears from neutral to drive, the engine speed stays constant, when before it would bounce around before slowing back down.

Thanks for the help!

-jason

http://www.canada355.com/
2005 Black LS Extd. I5 Z85/2WD
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post #12 of 21 (permalink) Old 11-03-2008, 02:04 PM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

Jason,

If you haven't replaced the fuel filter recently, do that too. You'll notice a difference - though not as much as cleaning the TB. I did both yesterday at 92,500 miles. It runs like day one, CEL is off, and the P0506 code is gone. Not bad for an hour's worth of work and $20 in parts and supplies. The amount of crap that runs out of a fuel filter that's been in the truck for a couple of years is amazing. I definitely need to to it more often.
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post #13 of 21 (permalink) Old 11-03-2008, 04:01 PM Thread Starter
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Re: P0506 (Idle Control System RPM Lower Than Expected)

yeahup, i've also been told to do that... next time i have a chance, i'm going to change the filter and replace the sparrkplugs, as well as checking all of the fluids.

-jason

http://www.canada355.com/
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post #14 of 21 (permalink) Old 11-18-2008, 11:00 PM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

i cleaned the TB also threw in plugs and a filter. fixed. probably just the TB
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post #15 of 21 (permalink) Old 09-07-2009, 12:37 AM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

ok the chevy colorado has the IAC valve it is located on the throttle body its the round cylinder on the body. and the reason everyone is having problems with them after they clean them is because there are little holes inside the body that go to the iac sensor once it gets wet you ruin your iac sensor thust ruining your throttle body i know this cuz i just cleaned mine and now im going to buy a new body. :( :( :(




I hope this helps evryone
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post #16 of 21 (permalink) Old 09-07-2009, 12:48 AM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

Quote:
Originally Posted by fire2maddog
ok the chevy colorado has the IAC valve it is located on the throttle body its the round cylinder on the body. and the reason everyone is having problems with them after they clean them is because there are little holes inside the body that go to the iac sensor once it gets wet you ruin your iac sensor thust ruining your throttle body i know this cuz i just cleaned mine and now im going to buy a new body. :( :( :(




I hope this helps evryone
Ummm......what you are thinking is the IAC valve is actually the motor to open/close the butterfly plate. We aren't having problems from cleaning the throttlebody, we clean it to eliminate problems like rough idle, low rpms, etc. Don't know how you cleaned yours but hundreds of us have done it without complications. If you took your truck to the dealer to get the TB cleaned, the tech would spray cleaner into the throttle body.

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post #17 of 21 (permalink) Old 09-09-2009, 05:44 PM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

i know were the motor is its in the same housing and i did my own so the little hole on the top inside of the butterfly there is a hole i didnt realize it but when i turned it up side down i got the fluid into the whole and i cleaned mine with choke and throttle body cleaner.
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post #18 of 21 (permalink) Old 09-09-2009, 07:05 PM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

Quote:
Originally Posted by fire2maddog
i know were the motor is its in the same housing and i did my own so the little hole on the top inside of the butterfly there is a hole i didnt realize it but when i turned it up side down i got the fluid into the whole and i cleaned mine with choke and throttle body cleaner.
The little hole on top is tied into the plastic purge hose on the front of the TB next to the wiring harness.

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post #19 of 21 (permalink) Old 05-10-2010, 07:25 PM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

check your fuel cap, it could be a vacum leak due to the fuel cap not sealing. an aftermarket fuel cap could cause it to not seal right

[><] PATRICK [><]
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post #20 of 21 (permalink) Old 12-15-2010, 10:34 PM
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Re: P0506 (Idle Control System RPM Lower Than Expected)

Quote:
Originally Posted by poqfisher
check your fuel cap, it could be a vacum leak due to the fuel cap not sealing. an aftermarket fuel cap could cause it to not seal right
The fuel cap that came on the truck broke, so i bought a new one from Auto Zone. This happened about six months ago. the service engine light has just come on in the past two weeks. If the fuel cap is the problem, if i buy a new factory type from the dealer, would this fix the problem or do you think damage has been done to the IAC valve?
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