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New IACV High Idling Problem


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JakeSK
Novice

Apr 15, 2015, 10:17 PM

Post #1 of 14 (1633 views)
  post locked   New IACV High Idling Problem  

Hi Everyone, I'm new so forgive me if I make any mistakes. I have a Mitsubishi Lancer Sedan 2.0L 2005 and I was having some Low idling problems so I imported a new IACV but now when I start the car cold it idles at 2000 - 2100 Rpm's. I've tried disconnecting the battery for 30 mins to restart the ECU but it hasn't changed anything. It runs high when cold but once it heats up its fine. Any help would be much appreciated.

Cheers, Jake


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Apr 16, 2015, 4:39 AM

Post #2 of 14 (1616 views)
  post locked   Re: New IACV High Idling Problem  

Imported a new IAC valve from what?

How did you come to the conclusion that it needed a valve? What kind of testing was done to prove this?

Is the check engine light on? If so, what trouble codes are stored?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 16, 2015, 6:31 AM

Post #3 of 14 (1613 views)
  post locked   Re: New IACV High Idling Problem  

Jake - Same questions and some more:
Just basics that it changed something by doing this and "why" is still the question. I would quit disconnecting the battery as IDK for these at all but you may be forcing it to "relearn" itself. I can't think of any engine that would be normal to run at over ~1,800 RPMs cold and not for that long totally dependent on HOW COLD.


Is it 100% normal now when warmed up and do you mean totally warmed up or what and how long of a run time?


Post any code #s for better help not YOUR interpretation of them,


T



JakeSK
Novice

Apr 25, 2015, 11:12 PM

Post #4 of 14 (1563 views)
  post locked   Re: New IACV High Idling Problem  

Hi, sorry for the late reply. I've been having some login issues. Anyway the 'check engine light' is not on and I've imported the new IACV valve from the US over eBay. I saw that whenever I unplugged the valve it did nothing whatsoever, I did the same on a few other cars and they all shot up in RPM's or went down in RPM's

Cheers, Jake


JakeSK
Novice

Apr 25, 2015, 11:16 PM

Post #5 of 14 (1561 views)
  post locked   Re: New IACV High Idling Problem  

Once again sorry for the late reply. Yeh it runs perfect when it has heated up, it slowly comes down after a while of running, as in when the car starts to heat up the revs come down. I'm thinking that the car is now overcompensating for the drop from my old IACV because my old one made the car stall because of how low it dropped the Rpm's but now the new one does the opposite.

Cheers, Jake


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Apr 25, 2015, 11:36 PM

Post #6 of 14 (1558 views)
  post locked   Re: New IACV High Idling Problem  

Code #s Jake! Stop unplugging things as that alone now sets a code to confuse this and would need a reset and new reading if already done doesn't count now,


T


* Log-in problems? I forget but it may only give you a temporary password if you don't choose one yourself that will expire? Been a while and not sure on site's settings for that. If an error message site is down and hasn't been for quite some time.........



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Apr 26, 2015, 4:20 AM

Post #7 of 14 (1552 views)
  post locked   Re: New IACV High Idling Problem  

The IAC is a stepper motor. Nothing is going to change if it's unplugged. All that's going to happen is you're going to set a false code as Tom pointed out.

You need to clean the throttle body is you haven't done that already.

First eliminate all vacuum or air leaks in the system.

Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle.



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JakeSK
Novice

Apr 29, 2015, 9:35 AM

Post #8 of 14 (1532 views)
  post locked   Re: New IACV High Idling Problem  

Hi Tom
I only unplugged the old one as a last resort, have not done that to the new one as I know it could damage it. I've cleaned the throttle body and checked the whole intake system for leaks many times! But I've found nothing. I'm selling the car so want it fixed ASAP.
Cheers, Jake


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Apr 29, 2015, 10:00 AM

Post #9 of 14 (1528 views)
  post locked   Re: New IACV High Idling Problem  

Just didn't want you to confuse it with codes that may not be pertinent in the mix. How are you checking for vacuum leaks? Sorry if you said but you claim none and may be none. All intake items, hoses, gaskets etc.


Some elusive. Easy if using the carb cleaner on spots way as it is flammable. I usually find them with just that but there's smoke testing, propane, wiggle tests on hoses, vacuum leak down on certain diaphragms and on and on.


I'll plead IDK for sure on this car if a reasonable incorrect idle just needs some time to self acclimate to after anything reset or fixed.


Understand you want this over with and sell it off.


Another wild though > Does throttle plate close all the way and properly?


T



Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Apr 29, 2015, 1:53 PM

Post #10 of 14 (1522 views)
  post locked   Re: New IACV High Idling Problem  

Seems that if the idle is high when cold and normal when warmed up the ECU is able to control the idle air control motor. Another thing to consider too is that if there is a vacuum leak, it should be flagging a lean code P0171. This vehicle is equipped with an air flow meter. Usually on air flow metered vehicles, vacuum leaks usually don't make them idle high, but will make them idle rough. If the leak is large enough it could cause a high idle, but 2100 you would definitely be hearing a hissing sucking noise from the leak.

How long has it been doing this? Has anyone messed with the speed adjusting screw?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Apr 29, 2015, 2:03 PM)


JakeSK
Novice

May 12, 2015, 11:36 PM

Post #11 of 14 (1446 views)
  post locked   Re: New IACV High Idling Problem  

My apologies again, I really do appreciate the time you all put it to replying and trying to help me. I've posted this problem on several other websites so it gets mixed up and the last 2 weeks were exam weeks for Uni students in Australia. I checked the Throttle plate and found it did close properly so I can rule that one out. The thing that bothers me is that it ran perfectly before it started to idle low. And when I changed it, it started the opposite problem, too high of an idle. I checked the other forums and found that most people do think it is an air leak. I checked the intake system again and found that the one side of the clips at the bottom of the 'Intake box' (where the Air Filter sits) was broken, possibly from when I changed the IACV originally and that it was not sitting properly. I put the other side in properly and fitted it as best I could to its original position and I am now waiting for it to cool down to check again. I'll repost again within the hour.

Cheers, Jake


JakeSK
Novice

May 12, 2015, 11:39 PM

Post #12 of 14 (1445 views)
  post locked   Re: New IACV High Idling Problem  

Hi Discretesignals
It has been doing this for about 3 months. Ever since I changed the old IACV to a new one because it was Idling to low and now the new one seems to 'over-compensate' and Idle to high. I am the only one who works on it and I haven't adjusted the speed adjusting screw.

Cheers, Jake


JakeSK
Novice

May 13, 2015, 11:49 PM

Post #13 of 14 (1428 views)
  post locked   Re: New IACV High Idling Problem  

Hello again, just to let everyone know I found the problem. When I was putting in the new IACV it appears that I broke one of the two hooks at the bottom of the Intake box and that caused it to not sit properly. Once I had put it in as best I could it sealed of the Intake box alot better than it had previously and sealed off any leaks. The Intake system was the problem, so for anyone having a similar problem, make sure to triple and quadruple check your Intake system because that is most likely the culprit!

Cheers, Jake


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

May 14, 2015, 7:21 AM

Post #14 of 14 (1418 views)
  post locked   Re: New IACV High Idling Problem  

Glad you found and solved it. Closing thread as solved and YOU can ask any moderator to reopen it at your request,


T







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