Search



Go Back   MustangForums.com > Ford Mustang Tech > 4.6L (1996-2004 Modular) Mustang > 4.6L General Discussion
Sign in using an external account
Register Forgot Password?
Search

4.6L General Discussion This section is for non-tech specific information pertaining to 4.6L (Modular) Mustangs built from 1996 to 2004.

Welcome to Mustang Forums!
Welcome to Mustang Forums.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!


Reply
 
 
 
 
Thread Tools Search this Thread
Old 09-11-2014, 10:58 AM   #1
Thedunzelmon
 
Thedunzelmon's Avatar
 
Join Date: Sep 2014
Vehicle: 2004 Ford Mustang GT
Location: New Jersey
Posts: 6
Arrow 2004 Idling issues

Okay ill keep things short because i have been having issues posting to this forum cause im new here. But my 2004 GT is idling funky when warming up. It surges between 700 and 900 rpm. When driving everything is fine no spitting or missing. No engine codes. Just this unusual idle. The car has an aftermarket intake and throttle body which i have checked and everything is on nice and tight. Thottle position sensor is new. I ordered a new IAC valve and am having trouble to find a new PCV valve for my motor. My car has 82000 miles and never did this until recently and i want to fix it before it gets worse. Is there something i didnt check? Something else it could be? Please help
This ad is not displayed to registered or logged-in members.
Register your free account today and become a member on Mustang Forums!
Thedunzelmon is offline   Reply With Quote
Old 09-11-2014, 12:53 PM   #2
Z28KLR
3rd Gear Member
 
Z28KLR's Avatar
 
Join Date: Nov 2009
Vehicle: 2001 GT
Location: SoCal
Posts: 906
Default

What brand IAC did you get? I ask because that is one of the few parts where an oem Motorcraft replacement is generally recommended over the ones that parts stores sell. That may possibly be your issue though, so post back when you get the new one on.

As far as the pcv valve, in my experience they usually do not need to be replaced. Pull it out and spray it with some carb cleaner. If when you shake it the little ball inside rattles freely and there is otherwise no damage (cracks etc) to the outer casing then it's good and can be reinstalled. If you do need a new one, Autozone etc should have it, it's not an uncommon item. You can also check Rockauto.com if local parts stores don't pan out.

Is this idle issue only at warmup?
__________________
__________________________________________

2001 Pussy Slayer Red GT convertible; all of the usual bolt-ons.

1967 Notch; 200 I-6, C4 auto
Z28KLR is offline   Reply With Quote
Old 09-11-2014, 10:01 PM   #3
Thedunzelmon
 
Thedunzelmon's Avatar
 
Join Date: Sep 2014
Vehicle: 2004 Ford Mustang GT
Location: New Jersey
Posts: 6
Default

I did alot of reading around and yes i ordered the OEM motorcraft IAC valve. I got the part off of late model restoration. It should be here around monday or so. As far as the idle goes it does it when it is warming up from a cold start, and it will also do it if say i left it to sit for an hour or so then went to drive it. It won't be completely cooled off, but as it gets to temperature it will surge between 700 and 900 rpm, then smooth out after driving. I am also going to replace the spark plugs coils and injectors soon before they begin to misfire. Ill get back to you once i install the new unit on monday.
Thedunzelmon is offline   Reply With Quote
Old 09-13-2014, 12:47 PM   #4
Thedunzelmon
 
Thedunzelmon's Avatar
 
Join Date: Sep 2014
Vehicle: 2004 Ford Mustang GT
Location: New Jersey
Posts: 6
Default

Quote:
Originally Posted by Z28KLR View Post
What brand IAC did you get? I ask because that is one of the few parts where an oem Motorcraft replacement is generally recommended over the ones that parts stores sell. That may possibly be your issue though, so post back when you get the new one on.

As far as the pcv valve, in my experience they usually do not need to be replaced. Pull it out and spray it with some carb cleaner. If when you shake it the little ball inside rattles freely and there is otherwise no damage (cracks etc) to the outer casing then it's good and can be reinstalled. If you do need a new one, Autozone etc should have it, it's not an uncommon item. You can also check Rockauto.com if local parts stores don't pan out.

Is this idle issue only at warmup?
I just got the new IAC today and installed it. The initial start was back to normal. it runs up over a grand and then slowly begins to slow down to 1000. Once it fell under though the surge was still there. It wasnt as bad as before or as rapid but it was still noticeable. I read that it could also be the spark plugs and coils, which i already have ordered new plugs and just need a little extra money before i can order new coils. Is there anything else i should check?
Thedunzelmon is offline   Reply With Quote
Old 09-13-2014, 02:28 PM   #5
Z28KLR
3rd Gear Member
 
Z28KLR's Avatar
 
Join Date: Nov 2009
Vehicle: 2001 GT
Location: SoCal
Posts: 906
Default

I seriously doubt it's either plugs or coils. If it were misfiring, yes. But surging, I would look at things like a possible vacuum leak. Probably not your problem, but might also be worth investing $6 in a can of MAF cleaner and giving that a try.

Could also be the upstream O2 sensors, but without a check engine light to lead you in that direction or other diagnostic equipment so you could view the data they're producing, I'm not going to recommend just going out and buying new ones for the sake of throwing (expensive) parts at the car.

Could even be EGR related. But again, without the cel coming on to at least lead you in that direction it's pretty tough to make a reasonable conclusion or diagnosis of that.
__________________
__________________________________________

2001 Pussy Slayer Red GT convertible; all of the usual bolt-ons.

1967 Notch; 200 I-6, C4 auto

Last edited by Z28KLR; 09-13-2014 at 02:31 PM.
Z28KLR is offline   Reply With Quote
Old 09-16-2014, 11:28 AM   #6
Thedunzelmon
 
Thedunzelmon's Avatar
 
Join Date: Sep 2014
Vehicle: 2004 Ford Mustang GT
Location: New Jersey
Posts: 6
Default

Quote:
Originally Posted by Z28KLR View Post
I seriously doubt it's either plugs or coils. If it were misfiring, yes. But surging, I would look at things like a possible vacuum leak. Probably not your problem, but might also be worth investing $6 in a can of MAF cleaner and giving that a try.

Could also be the upstream O2 sensors, but without a check engine light to lead you in that direction or other diagnostic equipment so you could view the data they're producing, I'm not going to recommend just going out and buying new ones for the sake of throwing (expensive) parts at the car.

Could even be EGR related. But again, without the cel coming on to at least lead you in that direction it's pretty tough to make a reasonable conclusion or diagnosis of that.
Alright man I found the problem. It was for a fact the plugs getting ready to go. I was able to take the car to ford for a free full point inspection and they told me that they pulled half the plugs out, and they all looked worn out. But they also found out that my trans needs new internals which is a 1200 dollar fix through them:/ but it is not too serious and will be addressed when i get the extra money i want my car running its best. Thanks for all your help!
Thedunzelmon is offline   Reply With Quote
Old 09-16-2014, 11:30 AM   #7
Thedunzelmon
 
Thedunzelmon's Avatar
 
Join Date: Sep 2014
Vehicle: 2004 Ford Mustang GT
Location: New Jersey
Posts: 6
Default

The Transmission doesnt need all new internals just a new input shaft bearing but thats a huge job in itself. Goddam 3650's :/
Thedunzelmon is offline   Reply With Quote
Old 09-16-2014, 10:15 PM   #8
Z28KLR
3rd Gear Member
 
Z28KLR's Avatar
 
Join Date: Nov 2009
Vehicle: 2001 GT
Location: SoCal
Posts: 906
Default

Just find a used 3650 and swap it in. Or for the money Ford wanted to replace 1 bearing I'm sure you could find a fully rebuilt unit with a warranty.
__________________
__________________________________________

2001 Pussy Slayer Red GT convertible; all of the usual bolt-ons.

1967 Notch; 200 I-6, C4 auto
Z28KLR is offline   Reply With Quote
Old 09-16-2014, 10:15 PM
MustangForums
Ford Mustang




Paid Advertisement

 
 
 
Reply

Tags
ford, iac, idle issues, maintenance, mustang 04

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not 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 Off
Pingbacks are Off
Refbacks are Off

Forum Jump

Advertising

Featured Sponsors
Vendor Directory
New Sponsors
All times are GMT -5. The time now is 07:15 PM.

© Internet Brands, Inc.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.

This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. Ford® is a registered trademark of the Ford Motor Company
Emails Backup