Idle surge with a/c or heat on only - Mustang Evolution

Go Back   Mustang Evolution > 1979-2015 Mustang GT || Tech and Talk > 1996-2004 Mustang GT



Reply
 
Thread Tools Search this Thread
Please support our sponsors and let them know you heard about them here!
Old 11-24-2010, 11:47 AM   #1
Registered User
Newbie
 
Join Date: Feb 2010
Region: Kentucky
Posts: 18
Idle surge with a/c or heat on only

Need help:
I have a 2002 mustang gt i replaced the iac the egr valve and sensors 02 sensors maf throttle position sensor spark plugs checked for vac leaks and nothing helped. The car idles fine unless i have the a/c on when i come to a stop the idle will jump up to 1000rpm and back down to 650 700 and continue going up and down until i continue driving again also the car is an automatic and when it shifts into overdrive it will hesaitate and then buck into gear. The car also tends to hesitate when I really step on it you can hear the air being sucked in but takes a min to get going any ideas would be a great help im running out.
roush727 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 11-24-2010, 12:15 PM   #2
Registered Member
Regular
 
GUDNEVL's Avatar
 
Join Date: Nov 2010
Region: North Carolina
Posts: 84
Re: Idle surge with a/c or heat on only

i would think(of course i may think wrong),that the a/c high idle is pretty normal,the air sound when you get on it,do you have a cold air intake?
__________________
1989 mustang gt,short headers,3.08 gears,off road h pipe,flows,cold air intake,smog pump delete,fresh tune up,push button start,gt fog light fix ,everything else pretty much stock
most recent mod:blown head gasket
GUDNEVL is offline   Reply With Quote
Old 11-25-2010, 12:32 PM   #3
Registered User
Newbie
 
Join Date: Feb 2010
Region: Kentucky
Posts: 18
Re: Idle surge with a/c or heat on only

yeah i know the idle should raise a little bit with the a/c on but it is surging it spikes up to about 1000 rpm and the drops to about 650 at a complete stop then right back up to 1000 a sec later and back down to 650 this continues until i resume driving
roush727 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 11-27-2010, 01:34 PM   #4
Registered Member
Regular
 
Tape's Avatar
 
Join Date: Apr 2007
Posts: 273
Re: Idle surge with a/c or heat on only

Quote:
Originally Posted by roush727 View Post
yeah i know the idle should raise a little bit with the a/c on but it is surging it spikes up to about 1000 rpm and the drops to about 650 at a complete stop then right back up to 1000 a sec later and back down to 650 this continues until i resume driving
when your low on refrigerant it will do this like you explain "650 at a complete stop then right back up to 1000 a sec later and back down to 650" I would bet your a couple of ounces low. when everything is serviced it will do it but just not every second.
Tape is offline   Reply With Quote
Old 12-09-2010, 10:11 AM   #5
Registered User
Newbie
 
Join Date: Dec 2010
Posts: 1
Exclamation Re: Idle surge with a/c or heat on only

Hello to everyone, I'm from Guadalajara Mexico and I own a 00 GT, I just have a similar problem, but mine goes down to even 250rpm, then goes up to 1500 and back to 650 when A/C is on, I'd just like to know whta could be wrong.

Thanks for your replies!!!!
Wakarimasen_san is offline   Reply With Quote
Old 12-09-2010, 10:35 AM   #6
Moderator Emeritus
Legacy
Regular
 
SpectorV's Avatar
 
Join Date: May 2003
Region: Alabama
Posts: 26,049
Send a message via AIM to SpectorV
Re: Idle surge with a/c or heat on only

yea as said get the system checked to see if its low and add if it needs it then check it out.
__________________
2003 Cobra Vert (Redfire) #3938 of 5082 @ 05/27/2003
472rwhp/493rwtq -Modification List - Dyno Sheet
2012 Mustang 3.7L M6 (Kona Blue)
2011 Ford Edge Sport (Red Metallic)
SpectorV is offline   Reply With Quote
Old 12-12-2010, 06:24 AM   #7
Registered User
Newbie
 
dshaley77's Avatar
 
Join Date: Dec 2010
Region: Florida
Posts: 10
Mine does this too...I added refrigerant and it fixed the problem. Then about a month went by and it started again. I'm almost 100% sure there is a leak somewhere....just havnt gotn around to get it checked out yet.
dshaley77 is offline   Reply With Quote
Old 12-14-2010, 02:50 AM   #8
Registered Member
Regular
 
Join Date: Dec 2010
Posts: 21
Quote:
Originally Posted by roush727
Need help:
I have a 2002 mustang gt i replaced the iac the egr valve and sensors 02 sensors maf throttle position sensor spark plugs checked for vac leaks and nothing helped. The car idles fine unless i have the a/c on when i come to a stop the idle will jump up to 1000rpm and back down to 650 700 and continue going up and down until i continue driving again also the car is an automatic and when it shifts into overdrive it will hesaitate and then buck into gear. The car also tends to hesitate when I really step on it you can hear the air being sucked in but takes a min to get going any ideas would be a great help im running out.
I would try cleaning the throttle body first. The iac may be compensating for your idle already, and may not have enough when ya kick the a/c on. You may also want to check your ground wires. When you turn the heat on, is the a/c light still on? Basically are you just turning the knob from blue to red? If so the compressor will still be turning.
__________________
2004 Cobra...

Mods: Kenne Bell 2.2H, Fore return system, SCT tuned, 26 spline input shaft, and DSS Pro-level axles.

http://www.facebook.com/LangsStangs
lxlaw is offline   Reply With Quote
Reply

Lower Navigation
Go Back   Mustang Evolution > 1979-2015 Mustang GT || Tech and Talk > 1996-2004 Mustang GT

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 On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
heat shield Senorjizzy Pre-2005 V6 Mustang 2 10-10-2009 12:50 PM
TF Track heat GOTGREENS 1996-2004 Mustang GT 4 03-09-2008 02:33 PM

» Like Us On Facebook



09:59 AM


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0

MustangEvolution.com is in no way associated with or endorsed by Ford Motor Company.