• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific Tech

94 GT HCI: Won't find /hold idle when Warm to Temp

  • Thread starter Thread starter 1994FiveO
  • Start date Start date Jun 10, 2023
1

1994FiveO

Member
Jun 10, 2023
4
1
13
Jun 10, 2023
#1
  • Jun 10, 2023
  • #1
Hi Guys.

94 GT Vert here. Car ran great with 100% stock set up.

Build
  • HCI Trick Flow Top End with Stage 1 Cam, 170 TW Heads, Street Burner Intake,
  • BBK shorties
  • OH H pipe
  • Magnaflow cat back.
  • Precision Stall 2800-3000 installed on the AODE.
  • Ted Jenkins @ Tuning Innovations tune with SCT Chip.

The issue I am having is the car with start, find idle in park and all gears, drive great up until the point I turn it off. Once I go to restart it, it will start and idle will bounce to 2k and maybe hunt for a few seconds before stalling. Sometimes I have gotten luckly to feather the gas for 20-30 secs around 2k rpm and it finds itself to idle.

It ONLY happens when warm. Once I let it sit for 30 mins it then fires back up and finds idle just fine.

Here is what is different on this build besides above.
  • Emissions (EGR) delete
  • MSD distributor (replaced Remanuf)
  • MAF 75mm 24#
  • 24# injectors
  • 255 Fuel pump
  • New alternator
  • New Battery

Here is what I have done:

  • Updated Chip to accommodate High stall converter increasing idle
  • Base Idle Reset (in gear parked idles 850-950 consistently, In park right at hair under 1k.
  • Replaced ECT Sensor
  • Replaced IAC Sensor
  • TPS checked in range of 1.0
  • Ran codes with only ones popping relating the EGR

What could it be
  • I have read it could be IAT or other sensors but if car ran well before?
  • Maybe MAF is ty but runs great all other times.
  • PIP sensor or Distrib? However runs well when cold started
  • TFI module? Read that it can get hot and malfunction during heatsoak


What do you guys think?
 

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,950
10,589
203
polk county florida
Jun 14, 2023
#2
  • Jun 14, 2023
  • #2
Looks like nobody has responded to this issue so I'll give it a shot, this type of issue can be simple like 'oh crap!! I can't believe I did that!' To ' well hell, that was ruff'
First thing to monitor would be fuel pressure, a temporary gauge mounted so you can observe it while driving, I make notes, I suffer from CRS.
You're gonna need to check for spark at the time it shuts down.
There is a checklist but it has to be done when the problem is occurring.

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

Cranks OK, but No Start Checklist for Fuel Injected 5.0 Mustangs model years 1986-1995 A word about this checklist before you start: it is arranged in a specific order to put the most likely failure items first. That will save you time, energy and money. Start at the top of the list and work...
www.stangnet.com
 
1

1994FiveO

Member
Jun 10, 2023
4
1
13
Jun 14, 2023
#3
  • Jun 14, 2023
  • #3
I did find a leak at my first injector on the fuel rail by the fuel line. I noticed a raw gas smell but couldnt figure it out until today when I saw white smoke coming off the injector.

Fuel was pooling on the manifold. This could be my issue or maybe just one of them. I will attack it this weekend and start again if not.
 
Reactions: General karthief
You must log in or register to reply here.

Similar threads

Engine Random Misfire at idle.
  • Gulftown980x
  • Jul 29, 2026
  • SN95 4.6L Mustang Tech
Replies
11
Views
210
SN95 4.6L Mustang Tech Jul 31, 2026
squeak93
M
Help! 2003 GT misfire when hot
  • Modular03
  • Feb 10, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
409
SN95 4.6L Mustang Tech Feb 13, 2026
Mustang5L5
T
Help with a 95 5L crank no start
  • TheBubbaJoe
  • Nov 4, 2025
  • 1994 - 1995 Specific Tech
Replies
3
Views
458
1994 - 1995 Specific Tech Nov 5, 2025
AeroCoupe
S
Fox '87 GT can't get to stay running
  • spilly
  • Mar 29, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2
Replies
27
Views
842
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jun 20, 2026
spilly
S
R
94’ SN95 - Intermittent lope & bogging at moderate rpm
  • Red5.0ho
  • Nov 2, 2025
  • 1994 - 1995 Specific Tech
Replies
5
Views
472
1994 - 1995 Specific Tech Nov 3, 2025
General karthief
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?