• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
  • Fox Engine Swaparoo

Not staying running!! Idle adjustment?

  • Thread starter Thread starter Diesel1277
  • Start date Start date Sep 27, 2019

Diesel1277

New Member
Sep 26, 2019
14
0
1
Tolland ct
Sep 27, 2019
#1
  • Sep 27, 2019
  • #1
I have a 1991 5.0 302 that I swapped into a 1995 bmw shell, I have the mustang ecu running the engine so everything that needs power should have it. I’m looking for things to check please. I have the ignition timing set close but have not set it with a timing light so that may be my issue itself, the engine has aftermarket internals mainly through ford racing and trickflow, everything except the crank shaft has been replaced I have .490 lift on the cam so I know it won’t be smooth.. anyway I have plenty of fuel due to putting a walboro 525 fuel pump and larger 18lb injectors. Anyway you guys would be able to shoot ideas as to why I can run it ok for about 2 minutes until it wants to die at idle? I can keep it running if I keep it above idle

Welcome to stangnet
do you have the diagnostic port? Is the spout there?
pull the spout and if it will idle, set the timing
check for vacuum leaks,we will start there.

I do not have a diagnostics port just the computer which has made my journey a struggle already lol, I will set the timing with a light but correct me if I’m wrong but I thought I saw you should get it warmed up a little before setting ignition timing? I have replaced the evap vacuum lines coming off the intake (I have a gt40 upper and lower intake ported by tmoss) and tried to go through the rest of them and replaced all that I could see. Although I just came across a breather that goes from my upper to Lower intake I believe I’m not quite sure what it is to be honest I will post a picture

PCV valve, there is also a screen under it that should be checked/cleaned

Ok I’ll look to clean that and put it back in, if that is not the issue do you think having the 525gph fuel pump is too much for the stock fuel regulator?

That's a lot of pump, aftermarket regulator?

No, the stock 30psi regulator and for some reason my fuel rail doesn’t have a shraider valve to see what’s flowing through so I might have to tap in just before the rail and see what the pressure is. I still have not gotten to timing it with a light but I have the weekend off so we’ll see how it runs after that and cleaning the pcv, I have that to one of the ports on the upper intake I don’t know if it matters which port?

I just got done doing a full rebuild with eagle rods, trickflow twisted wedge pistons which makes the engine bored .040 over making it a 306, twisted wedge heads, trickflow valves and roller rockers, ford racing hydraulic lifters, trickflow cam .490 lift, ported upper and lower gt40 intakes, 24lb injectors, edelbrock fuel rails, walboro 525 fuel pump, and aeromotive fuel regulator all run with -6AN fuel line set at 36psi, BBK 70mm throttle body, BBK MAF for 24lb injectors, ford racing dual timing chain. I set my base timing to 12 for initial start up and it sounded to be running good but wouldn’t idle so I adjusted the set screw on the tb until it could idle itself and checked timing with a light, then tried to run it. The idle was surging so I went to set my tps voltage but in order to do that I had to adjust the idle screw back almost 3 full turns and when set at .987v it wouldn’t idle but with my foot slightly on the pedal would stay running smooth. I replaced the IAC (which made my intake now whistle crazy loud?) and it runs smoother but still wants to die at idle. Do I need a tune or can I adjust the idle up to where it doesn’t die out and catches itself?
 

Attachments

  • 5A038332-08FE-4DBC-9D50-255569AAB78D.webp
    267.1 KB · Views: 213

tsiemens

my welding skills arent really skills
Jul 14, 2018
136
26
38
ontario
Sep 28, 2019
#2
  • Sep 28, 2019
  • #2
how hard was it to get that pcv valve out of there with the intake on?
 

Diesel1277

New Member
Sep 26, 2019
14
0
1
Tolland ct
Sep 28, 2019
#3
  • Sep 28, 2019
  • #3
It wasn’t bad at the valve end but getting it back on the upper intake will be a pain due to the port being behind and under
 

tsiemens

my welding skills arent really skills
Jul 14, 2018
136
26
38
ontario
Sep 28, 2019
#4
  • Sep 28, 2019
  • #4
my vacuum lines going under the intake are shot anyway but for a few months I've been torturing myself with figuring out how to change that
 

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
27,892
10,550
203
polk county florida
Sep 28, 2019
#5
  • Sep 28, 2019
  • #5
Just pop the upper off, easy peasy, makes for quick work on the vacuum lines, pcv and the screen. The grommet is likely shot too.
this may help

1990 5.0 Mustang vacuum/emissons issues

Help! I just purchased my 1990 Mustang 5.0, 5 speed, original "7-Up" convertible and it had been non-operational since 2001. In evaluating this 61 K original miles beauty, the previous owner had done some R&R on the lines that attach to the plenum chamber and I am at a total loss of how to...
www.stangnet.com
 
Reactions: tsiemens

tsiemens

my welding skills arent really skills
Jul 14, 2018
136
26
38
ontario
Sep 28, 2019
#6
  • Sep 28, 2019
  • #6
I eliminated my egr just today and i finally see the pcv. Next time they should bury it under more crap....
 

Diesel1277

New Member
Sep 26, 2019
14
0
1
Tolland ct
Jun 5, 2020
#7
  • Jun 5, 2020
  • #7
Hey guys, I got my car tuned and it idles and runs great now but there’s always something. I idled it up to around 200 degrees to make sure the cooling system was working but it was overflowing when it hit temp and wouldn’t stop until I shut it off. I let it cool and tried to add coolant and run it again and the same thing happened. I had a Gatorade bottle with a tube into it going to the bottom and the bottle had fluid in it and by the time the car cooled down it has sucked the fluid out of the bottle. I’m going to make a bigger overflow tank out of aluminum tomorrow but does anyone have any input on if that seems to be a bleeding issue or do I have something else going on?
 
You must log in or register to reply here.

Similar threads

W
Engine My engine dies after running 10 to 15 minutes under high heat.
  • Wylieone
  • Jun 21, 2026
  • Fox 5.0 Mustang Tech
Replies
7
Views
139
Fox 5.0 Mustang Tech Jun 22, 2026
Mustang5L5
M
93 5.0 Microsquirt with Stage 3 trickflow tuning issues
  • marxpreston11
  • Jun 22, 2026
  • Digital Self-tuning Forum
  • 2 3 4
Replies
67
Views
811
Digital Self-tuning Forum Jun 25, 2026
Mustang5L5
K
Resolved Need some assistance. Holley Terminator X alongside H/C/I. Very rough/inconsistent idle
  • karhoot
  • Jun 6, 2026
  • Fox 5.0 Mustang Tech
Replies
0
Views
80
Fox 5.0 Mustang Tech Jun 6, 2026
karhoot
K
M
01 mustang 3.8 fuel pressure issue
  • Mhaley2006
  • May 29, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
99
1996 - 2004 SN95 Mustang -General/Talk- May 29, 2026
Mhaley2006
M
J
1990 fox starts on starting fluid only
  • Jfox
  • May 14, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
9
Views
176
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- May 15, 2026
AeroCoupe
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
  • Fox Engine Swaparoo
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?