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2006 CTS-V
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Discussion Starter #1
2006 CTS-V (6.0 LS2) The other day I noticed some surging at cruising. Then it threw a check engine light and the code showed Lean condition. Checked under the hood and found that the air intake had backed off of the air filter box. (All air was still going through the MAF sensor though. Just not the air filter.) I figured it's a good time to clean the MAF. So I bought a can of MAF cleaner, removed the MAF, cleaned it per instructions. While I was in there, also pulled the Throttle body and cleaned it also. Reassembled, started. All seemed fine, until I touched the throttle. RPM's jumped up and stayed up. Now it's idling at 1,750 RPM instead of the normal 800. Tried resetting the computer by disconnecting the battery. No improvement. Drove it for about 20 minutes at 65 mph (10 minutes to next highway exit and back) Still no change.

I've searched all over. Found some folks saying there's a learning process it needs to go through. (I figured the 20 minute drive would do that. Do I need to drive more or differently?) I've also found folks saying if you touch the blades on a fly-by-wire throttle body "you've ruined it". (With the TB off, I opened and held open the blades to clean it, but I don't see how that would "ruin" it.)

Any guidance would be greatly appreciated. Thanks in advance.
 

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This exact same thing happened to me. It takes a while...at least mine did. Like 3-4 days of it. It also threw a code but after the several days the check engine light went off and the idle went back to normal. I will admit I was starting to panic a little cuz it was taking so long but I waited it out and now its all good.
 

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2006 CTS-V
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Discussion Starter #5
I'm just going to take it out for a drive cycle each evening and see what happens. I looked up the "GM drive cycle" and found it here: http://www.obdii.com/drivecycle.html. It's kinda hard to do the deceleration (to 20 MPH) when the damn car now IDLES at 25 MPH (in 4th gear).

Question for you guys who had this issue: Do you remember if, as you were driving, it gradually improved (idle RPM came down a little each day) or just one day you started up and idle was back at 800 RPM?

Thanks, Steve
 

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I'm just going to take it out for a drive cycle each evening and see what happens. I looked up the "GM drive cycle" and found it here: http://www.obdii.com/drivecycle.html. It's kinda hard to do the deceleration (to 20 MPH) when the damn car now IDLES at 25 MPH (in 4th gear).

Question for you guys who had this issue: Do you remember if, as you were driving, it gradually improved (idle RPM came down a little each day) or just one day you started up and idle was back at 800 RPM?

Thanks, Steve
Mine was at high idle then the next day it wasn't. I least that is how I remember it... :suspect:
 

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Discussion Starter #7
I've been taking it for drives every evening, encompassing all of the conditions to meet the GM Drive Cycle definition. Still no change yet. Tonight will be the 5th cycle. Becoming doubtful this will correct itself.
 

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The throttle body could be worn out. This wear didn't manifest itself when it was dirty because the dirt helped seal it up. Now that its clean, it can pull more air around the worn throttle blade causing a high idle condition.

Sounds crazy but I've seen it happen. To combat it on my MR2, I plugged the idle air port....worked like a champ for 7 years of driving. I left the IAC motor plugged in and the car never knew the difference but it was a good bit dumber than this car is.

Based on that, I haven't cleaned mine and it runs fine.
 

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2005 CTS-V
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The service manual for the 2005 CTS-V (I don't have a 2006-07 manual) does not provide a idle relearn procedure even though it contains them for other CTS engines. It does say to disconnect the battery for 30 minutes to address idling issues. This has worked for me on a couple occasions.

The CTS-V FAQs contains a relearn procedure as follows: If the battery is disconnected, the electronic throttle control (ETC) may forget the zero throttle position too. If you find that your CTS runs poorly, you will have to have the re-learn the position.

To do this, turn the key to the run position with the engine off for at least three minutes. Then turn the key to the off position. Start the engine and let it idle for 30 seconds. Turn the engine off and restart.

Recheck the under hood components to make sure you do not have a vacuum leak, perhaps away from the area of the original issue. For example, check the hoses at the MAP on the rear of intake manifold passenger side, the PCV hoses, etc.
 

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Discussion Starter #11
I've checked thoroughly for leaks and found none. I've only touched items between the air filter housing and the throttle body. The one small vac hose that goes from the intake tube to the passenger side valve cover I checked also. Strange thing is every time I start it cold, the idle is perfect at 800...UNTIL I touch the accelerator pedal. Then it shoots up and stays up (at about 1750). If there was a vac leak, I wouldn't think it would ever idle steady at 800. Agree?

This thing's been really frustrating, but I really appreciate everyone's input. Thanks!
 

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2005 CTS-V
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I agree that a vacuum leak would be constant - I did not pick up on the fact that cold idle was 800 rpm until the throttle was touched. That would seem to limit the issue to a throttle position circuit issue.
 

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Discussion Starter #13
Update: I drive it every night for 6 days, completing the "drive cycle" each time. On the 6th day, it still idled at about 1750 when I first come to a stop, then in 20-25 seconds settled down to 1,200. This past Monday, I decided to try to drive it to work (64 miles round-trip) about half back roads, half stop and go city. After two days of that, still no further improvement. I'd estimate I've driven 230 miles and still it's not back to normal. Tonight I tried swapping out with a rebuilt throttle body and absolutely no change. So I put the original back on. This is ridiculous. I can't believe it can take this long to "learn". Any other thoughts?

Starting to think it'd be easier to take it to a shop to have the idle learn reset.

Anyone in the MD/DC/N VA area have a tech 2 or diagnostic tool and want to make a few bucks doing a reset?
 

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Im in Maryland. Work at andrews afb and have a reader you can use. Im actually about to do a throttle body/maf/fuel injector cleaner soon.
 
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