Idle control, Dodge truck - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> General Rodding Tech
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 06-18-2010, 12:59 PM
Member
 
Last photo:
Join Date: Jan 2003
Location: tennessee
Posts: 5,912
Wiki Edits: 0

Thanks: 0
Thanked 7 Times in 7 Posts
Idle control, Dodge truck

Maybe a bit off topic since it is not a hotrod but I just bought a 1999 Dodge 1500 4x4 to use on my farm and it has an idle problem I can't figure out. When first started or dropping down from running at a higher RPM it idles just fine, smooth and not rough at all, but after 30 to 45 seconds it starts to idle really rough and making a loud hissing noise form the idle air intake in the throttle body, this is accompanied by the normal exhaust fumes associated with an extremely lean mixture but the fumes are not present until the hissing starts. The engine is obviously experiencing a severe vacuum leak apparently caused by an improperly operating idle control but would these symptoms indicate a bad idle controller (idle control motor?) or would the circuit be to blame? Any ideas on where to start to diagnose this problem?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 06-18-2010, 01:58 PM
Race The Truck
 

Last journal entry: Son's Truck
Last photo:
Join Date: Mar 2006
Location: Arizona
Age: 58
Posts: 645
Wiki Edits: 0

Thanks: 4
Thanked 1 Time in 1 Post
Do you have any trouble codes? Next do you have a scanner? I had to break down and buy one for my truck just to work on it. Second I would look at getting a shop manual off of ebay 25-30 bucks make a big difference in trouble shooting.

Craig
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 06-18-2010, 02:56 PM
Member
 
Last photo:
Join Date: Jan 2003
Location: tennessee
Posts: 5,912
Wiki Edits: 0

Thanks: 0
Thanked 7 Times in 7 Posts
I guess I forgot to mention an important part of the problem, No there are no codes, when I run a scan it just comes up no codes found.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 06-18-2010, 04:27 PM
Registered User
 

Last journal entry: Some More Roll Cage Fabrication
Last photo:
Join Date: Apr 2010
Location: Ohio
Age: 31
Posts: 233
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
How does the truck run down the highway? IAC carbon buildup is an issue on these vehicles. The carbon buildup blocks the IAC from turning properly and the "threads" get messed up. Usually when that happens the Idle acts up when coming down from a higher RPM. When the engine is at highway speed the IAC is fully opened and should have no effect on engine performance. When the truck returns to Idle it closes and opens in order to achieve the correct Idle rpm.
It is not something silly like a purge valve for the EVAP is it? What happens if you shut the truck off and then restart it? Is the noise still there? Pull the vacuum line from the brake booster and induce a vacuum leak. Does the noise go away? Also, is this a V10 by chance?

Last edited by ethn_bert; 06-18-2010 at 04:36 PM.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 06-18-2010, 05:00 PM
Member
 
Last photo:
Join Date: Jan 2003
Location: tennessee
Posts: 5,912
Wiki Edits: 0

Thanks: 0
Thanked 7 Times in 7 Posts
360 engine, when first started or coming down from high RPM it will idle just fine for about 30 to 45 seconds or sometimes it takes longer than a minute for the problem to start. After the problem starts and the idle becomes rough I can shut the engine off and immediately restart it and the cycle starts all over again, that is it will idle ok for a short time but then it starts running rough again. The hissing sound is definitely coming from the idle air port in the throttle body so it is definitely the idle control. I can take the air filter housing off and start the engine and everything starts out normal but after about half a minute or so, sometimes a bit longer than a full minute, the hissing sound starts in the idle air port. This hissing or sucking sound starts out gradually then increases in intensity until it gets quite loud and the engine will hardly idle at all, open the throttle slightly and it runs fine however so it is definitely the idle circuit. After revving up the engine or driving the truck it will idle ok for the short time it takes for the problem to start but after it starts to run rough it will continue to idle rough until the engine is revved up or shut off and restarted.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 06-18-2010, 05:26 PM
Registered User
 

Last journal entry: Some More Roll Cage Fabrication
Last photo:
Join Date: Apr 2010
Location: Ohio
Age: 31
Posts: 233
Wiki Edits: 0

Thanks: 0
Thanked 3 Times in 3 Posts
What happens if you induce a vacuum leak?
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 06-19-2010, 08:26 AM
Race The Truck
 

Last journal entry: Son's Truck
Last photo:
Join Date: Mar 2006
Location: Arizona
Age: 58
Posts: 645
Wiki Edits: 0

Thanks: 4
Thanked 1 Time in 1 Post
OK, Not just a code reader a scanner to see the values the truck should be running at. With that you can find the area that need looking at. I have a 300 buck cheap one from autozone does obd1-2 You may want to try one of the Dodge forums also. Tell I got the shop manual and the scanner I was shooting in the dark.

Craig
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 06-19-2010, 11:13 AM
Registered User
 
Last wiki edit: Hand cleaner Last photo:
Join Date: Jun 2008
Location: Houston
Posts: 170
Wiki Edits: 3

Thanks: 0
Thanked 2 Times in 2 Posts
a few things that come to mind, a weak O2 sensor could cause the ECM to think the motor is running rich/lean when its not. the ECM leans/richens the mixture out and the RPM drops, then the ECM opens the IAC more to bring the RPM back into the target range.

an internal vacuum leak, the gasket on the plate on the bottom of the intake is a pretty common problem. pull the PCV valve from the valve cover and block the hole, then check for vacuum at the breather hose.
i've seen both of these cause the symptoms you describe.
of course there are other things that can do it, fuel problems, the MAP sensor shifting range, EGR problems.
other than an intake leak, you really need a scanner to check it.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 06-19-2010, 03:11 PM
Member
 
Last photo:
Join Date: Jan 2003
Location: tennessee
Posts: 5,912
Wiki Edits: 0

Thanks: 0
Thanked 7 Times in 7 Posts
Thanks I will do those checks. I have already replaced the O2 sensor but that was for another problem, I will check it again anyway because I realize being new is no 100% guarantee that it's working properly. I have a scanner but that's another puzzle because it checks out ok and does not pull up any trouble codes.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 06-19-2010, 04:58 PM
Race The Truck
 

Last journal entry: Son's Truck
Last photo:
Join Date: Mar 2006
Location: Arizona
Age: 58
Posts: 645
Wiki Edits: 0

Thanks: 4
Thanked 1 Time in 1 Post
I'm confused your scanner only reads trouble codes? If so it not going to help you. you need one the will read the value coming from each component in mv's that way you know if the part is working right. Still from there you need a meter to measure value from point a-b with is in the shop manuals Only other way to do it is start replacing parts!

Craig
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 06-19-2010, 06:55 PM
Member
 
Last photo:
Join Date: Jan 2003
Location: tennessee
Posts: 5,912
Wiki Edits: 0

Thanks: 0
Thanked 7 Times in 7 Posts
Quote:
Originally Posted by ChevyTruckGuy
I'm confused your scanner only reads trouble codes? If so it not going to help you. you need one the will read the value coming from each component in mv's that way you know if the part is working right. Still from there you need a meter to measure value from point a-b with is in the shop manuals Only other way to do it is start replacing parts!Craig

I mean according to the scanner everything is ok and nothing changes when the problem starts except the RPM and a lean mixture. As far as the computer is concerned (apparently anyway) there is just a large vacuum leak which in effect it is but it is originating at the idle air port in the throttle body.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 06-20-2010, 04:55 AM
Race The Truck
 

Last journal entry: Son's Truck
Last photo:
Join Date: Mar 2006
Location: Arizona
Age: 58
Posts: 645
Wiki Edits: 0

Thanks: 4
Thanked 1 Time in 1 Post
Ok, Weird you should be showing something! did you try the Dodge fourms? You might try looking in one of the cheap manuals at the auto parts store in the trouble shooting section may get lucky. My truck was having some of the same problems but mine was a big old list of thing including electrical problem where thing where wire up wrong. good luck

Craig
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 06-20-2010, 07:25 AM
1ownerT's Avatar
Home School Valedictorian
 
Last wiki edit: Health and safety in the shop or garage Last photo:
Join Date: Dec 2004
Location: Iowa
Age: 53
Posts: 1,645
Wiki Edits: 4

Thanks: 0
Thanked 3 Times in 3 Posts
As mentioned before the the bottom of the intake manifold has stamped tin plate on it, they are notorious for the gasket to leak. The idle can be crappy, it will use oil, and will rattle like it has a tank of bad gas.
A quick check is to open the butterflies and look into the bottom of the intake with a flashlight, if the gasket is bad it will be covered with a oil film. It is thought that the aluminum intake and stamped sheet metal pan expand and contract at different rates and shreds the gasket.
It takes me about four hours to change one out, taking time to thoroughly clean everything.
This: http://www.hughesengines.com/Index/p...p?partid=22220 is what I used on my Dodge.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 06-20-2010, 02:33 PM
Member
 
Last photo:
Join Date: Jan 2003
Location: tennessee
Posts: 5,912
Wiki Edits: 0

Thanks: 0
Thanked 7 Times in 7 Posts
Fixed it, it was the idle control motor that was malfunctioning. Replaced it with a new one and it idles fine now.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 06-21-2010, 03:47 PM
cranky1's Avatar
Just stuck
 
Last photo:
Join Date: Apr 2008
Location: Pasagetdowndena, TX
Age: 63
Posts: 434
Wiki Edits: 0

Thanks: 14
Thanked 0 Times in 0 Posts
Is the idle air control similar to the ones that were used on the eariler engines, like on a 1990? I got fed up with the one that was on a V6 and just took it off. The throttle body had an adjustment screw that kept the idle from going so low that it would die...kinda surprised me that it was there.
Reply With Quote Quick reply to this message

Recent General Rodding Tech posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
acceleration flat spot in carb. corvettetonybone Engine 17 04-13-2013 08:31 PM
dodge truck question...... skylark65 Suspension - Brakes - Steering 4 08-24-2009 01:40 PM
I'm going to make a bonfire out of my car blown69stang Engine 36 08-22-2005 03:36 PM
73 dodge truck Rodder318 Body - Exterior 2 04-05-2003 08:48 AM
Dodge show truck 5.0Towncar Hotrodders' Lounge 4 03-09-2003 09:45 AM


All times are GMT -6. The time now is 06:11 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.