Rough, loping idle and random attempts to die

MSTNGGRL1995

New Member
Apr 18, 2020
1
0
1
British Columbia
Hey guys

I've got 1995 5.0 GT. I've had it for 2 years and it's always had a bit of a rough idle, but it's gotten progressively worse. When I say rough idle I mean that when I start it the RPMs rev up to about 1200, then drop to 1000, then drop to about 750. It then proceeds to repeat this process several times before finally settling at an idle around 750, but it doesn't really settle, every few seconds in kinda rumbles and then drops to about 600 RPMs before jumping back up to 750. It also does this little jump every time I put I take it out of park to change it to another gear, and it will do it continually anytime the car is stopped and idling. Also, every once in a while when the engine's cold and I've left home, the first stop sign I come to the engine tries to die, the RPMs drop to almost nothing, but if I hit the gas hard and fast enough she'll keep going. I'm thinking the problem is my IAC but I would love to hear any ideas you guys might have, or if anyone else has had this problem with their stang. I also tried to test the IAC by unplugging it, but even with the engine warm, the engine started and then completely died... don't know if that's normal?

I also made a list of possible causes that have already been dealt with so you guys know what I've already fixed :)
Vacuum Leaks
Air filter
Dirty throttle body
Ignition timing
 
  • Sponsors(?)


jozsefsz

5 Year Member
Aug 11, 2013
1,144
271
114
49
Cleveland OH Area
An incredibly common problem, and your solution is here: http://forums.stangnet.com/showthread.php?t=698148

In general, the idle stop-screw and air-bleed need to be set to allow the car to continue to run (at low idle) with the IAC disconnected. This will largely eliminate the surging idle you're experiencing. Go through the whole check-list, it's time-tested. Some stuff you don't have to worry about for a 95 Mustang - especially getting the TPS voltage exactly correct (our computer adjusts for it). But most of it does.
 
  • Useful
Reactions: General karthief
Thread starter Similar threads Forum Replies Date
kingc cam overlap and lope/rough idle SN95 4.6L Mustang Tech 20
K Rough, loping idle... SVT Tech Forum 16
A Rough/Loping Idle, Hesitation, Sulfur Smell SN95 4.6L Mustang Tech 20
93silverlx50 Engine Car in limp mode, fuel spitting out of tailpipes, missing rough idle Fox 5.0 Mustang Tech 9
markinms Engine surges, cutouts, rough running during acceleration - Help Please! Fox 5.0 Mustang Tech 5
C Engine Gray smoke from exhaust. Smells like gas. Fox 5.0 Mustang Tech 15
B 1999 3.8 V6 rough start and slight miss SN95 V6 Mustang Tech 0
M Engine Ignition Timing Issues 1985 Fox Fox 5.0 Mustang Tech 2
9 Engine 92 5.0 Running Rough Fox 5.0 Mustang Tech 8
R Engine My 95 gt idling rough 1994 - 1995 Specific Tech 5
G mustang running rough after car wash 1996 - 2004 SN95 Mustang -General/Talk- 10
K Engine New Built Engine - Rough Start and Idle Surge Fox 5.0 Mustang Tech 3
Sampinator Hard downshift OD to 3rd 1996 - 2004 SN95 Mustang -General/Talk- 1
E 2010 Mustang GT - randon, intermittent, fresh hard starts with rough idle. 2005 - 2014 S-197 Mustang -General/Talk- 0
B Cold Start Rough Idle Fox 5.0 Mustang Tech 9
Xenogenesis Engine Idles rough, misfires at idle, smells rich, but codes say it's lean on both banks SN95 V6 Mustang Tech 9
J 93 mustang breaking up during acceleration 2.3L (N/A & Turbo) Tech 11
S Installed new intake and now car idles rough and turns off 1996 - 2004 SN95 Mustang -General/Talk- 7
J Engine 93 lx 2.3l runs terrible 2.3L (N/A & Turbo) Tech 9
T Engine 1994 mustang gt Rough idle, misfire under acceleration 1994 - 1995 Specific Tech 2
evintho Engine '93 running rough, especially at low rpm's and idle. Fox 5.0 Mustang Tech 1
D 1994 V6 rough idle after head rebuild 1994 - 1995 Specific Tech 0
P Carb, Fuel, or Ignition issue? Intermittent running rough 1965 - 1973 Classic Mustangs -General/Talk- 15
90-06stangs Rough idle. 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 7
J 04 GT New intake manifold and car now has a rough idle 1996 - 2004 SN95 Mustang -General/Talk- 5
P 95 mustang gt running rough 1994 - 1995 Specific Tech 0
LarsD What's it Worth? Whats my 91 Hatch worth roughly? What is it Worth?!?!? 18
R 2000 mustang runs rough and dies when warm SN95 V6 Mustang Tech 10
P Just arrived with a 1965 289 and a 1973 Mach I - and a vacuum leak solved The Welcome Wagon 1
D 1997 4.6 runs rough SN95 4.6L Mustang Tech 1
K What's it Worth? Seeking rough valuation on manual 1967 Coupe w/ 351 Windsor What is it Worth?!?!? 2
0 2003 Ford Mustang V6 3.8L gets around 12mpg and seems to shake a bit when started cold and has a bad rough idle when warm SN95 V6 Mustang Tech 5
S Engine 5.0 Running Rough (1990) Fox 5.0 Mustang Tech 1
Vaughnmx Engine 1990 fox car runs great unti it goes into closed loop runs vary rough popping backfire no power please help Fox 5.0 Mustang Tech 14
L Engine Rough Idle at Start, Possible CMCV Vacuum Leak 2015+ Specific Tech 0
N Engine Rough idle Fox 5.0 Mustang Tech 1
K MY17 engine rough running 2015+ Specific Tech 0
P 1995 GT 302 5.0 with rough idle and weird behavior (with video) 1994 - 1995 Specific Tech 1
D Engine Vacuum problem Fox 5.0 Mustang Tech 14
Wesley.davis 2004 Mustang Gt running really rough SN95 4.6L Mustang Tech 2
D Engine 2002 V6 Sputtering On acceleration SN95 V6 Mustang Tech 0
COramprat 2002 GT Intermettant rough idle and shut down SN95 4.6L Mustang Tech 4
S Rough idle fixed! 2005 - 2014 S-197 Mustang -General/Talk- 2
N 2000 Gt feels rough after driving in rain!!!! SN95 4.6L Mustang Tech 1
L 88 gt rough idle smell of fuel white smoke out of exhaust Fox 5.0 Mustang Tech 13
8 Rough idle and Steering Column vibration at idle and start. Fox 5.0 Mustang Tech 32
H Mustang running rough 1996 - 2004 SN95 Mustang -General/Talk- 3
nick_obryan 18 Ecoboost Mustang rough startup and white smoke? 2015+ (S550) Mustang -General/Talk 1
D 98 Rough idle and ride after motor and tranny mounts SN95 V6 Mustang Tech 2
C 2003 3.8 rough idle and shake 1996 - 2004 SN95 Mustang -General/Talk- 1
Similar threads