Idle control valve

M

miser143

New Member

Oct 2, 2024

19

1

3

New york

Saturday at 9:40 PM

#1

• Saturday at 9:40 PM

• #1

Hello everyone. I have a 1991 mustang gt that had several idle problems. Today I took it for a drive around 20 blocks. But I had the idle control valve disconnect. And the idle was good around 900 or 1000 .also it did not turned off on stop light also I pushed it hard that you can listen to the back tires peel out . On park the idle is around 1000 rpm.can eny one tell me way it ran better with the idle control valve disconnect. Thanks.

 

8

86HO5.0

Active Member

Apr 18, 2023

266

178

53

Raleigh, NC

Yesterday at 4:07 AM

#2

• Yesterday at 4:07 AM

• #2

Check for codes. If the car idled well with the IAC disconnected you either have a vacuum leak or the base idle is set too high. A base idle reset is likely needed.

Please take the time on your response and use proper English and punctuation, your previous post is very difficult to read.

 

Reactions: DadLife0724

manicmechanic007

5 Year Member

Sep 26, 2017

2,562

727

143

Roy, Utah

Yesterday at 4:09 AM

#3

• Yesterday at 4:09 AM

• #3

Drive it for 5-10 minutes not 20 blocks
That's to get it to operating temp
If you have a vacuum leak they generally will run better with the IAC unplugged
Check the codes, pro like me would watch the O2 sensors switch using a NGS on your OBD1 1991
That's to see if it is "slammed" lean or not, see whether the O2 sensors "switch" not
We had to backprobe or use the breakout box before the NGS came out

 

AeroCoupe

lube between the nut and the face. I know my lubes

Founding Member

Oct 28, 2001

6,191

4,291

183

Claremore, OK

Yesterday at 7:46 AM

#4

• Yesterday at 7:46 AM

• #4

Go to the “Fox 5.0 Mustang Tech” section at the top of this section you posted in. Scroll down and the first thread in the “Sticky Threads” guides you on how to pull codes if you do not already know how to do this.

This is a good code reader if you do not already have one:

https://a.co/d/04NH0PES

To set the base idle go to this thread:

Thread 'Help me create the "Surging Idle Checklist"'

Apr 10, 2005

Updated 05 July 2022 to add rough idle when cold and smooth idle when up to normal operating temperature. See the EGR tech information, section #15 for more help.

Many of you are familiar with the "Cranks OK, but No Start Checklist for Fuel Injected Mustangs" checklist and the No Crank Checklist. They are very effective in finding and eliminating the problems by use of a systematic process that checks and eliminates possible causes. This idle problem checklist will use the same troubleshooting strategy and methodology.

By the term surging idle, I mean an idle that...

• jrichker
• 1986 1993 86-93 check engine light code 67 cranks ok dump codes eec-iv mustang no start
• Replies: 575
• Forum: Fox 5.0 Mustang Tech

Scroll down to post #2.

 

Reactions: General karthief

General karthief

wonder how much it would cost to ship you a pair

Mod Dude

Aug 25, 2016

28,114

10,733

213

polk county florida

Yesterday at 11:18 AM

#5

• Yesterday at 11:18 AM

• #5

I'm interested in how long you have owned the car and what, if any, modifications done by you or the previous owner.
That tech forum is highly recommended and very usful, make me look like a hero mechanic.

 

Reactions: Potomus Pete and AeroCoupe