Engine Rough Idle at Start, Possible CMCV Vacuum Leak

larsond12

New Member
Apr 4, 2019
1
0
1
26
Wilmington, DE
Hi,

I have a 2015 salvaged coyote in a 67 mustang running on the control pack. Everything is up and running, but it seems to have a rough idle at start. The idle continues to be rough until I rev the engine and it settles down to normal at around 1000rpm for about 5 seconds, after 5 seconds the idle begins to rev up similar to a vacuum leak on a carburetor and is not consistent. The more I rev the engine the better the idle gets and continues to idle correctly for longer. I have a feeling it is most likely a CMCV vacuum leak but I guess it could be a stuck throttle body or faulty ground to the accelerator pedal sensor. I also totally winged the vacuum plumbing to the CMCV's based on a forum I read because I am not using a brake booster.

Here Is the thread :
https://thefactoryfiveforum.com/sho...tion-Regarding-2015-2016-Coyote-CMCV-Plumbing )
 
  • Sponsors(?)


Thread starter Similar threads Forum Replies Date
K Engine New Built Engine - Rough Start and Idle Surge Fox 5.0 Mustang Tech 3
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
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
8 Rough idle and Steering Column vibration at idle and start. Fox 5.0 Mustang Tech 32
1 92 Gt Rough Idle On Cold Starts (long) Fox 5.0 Mustang Tech 2
JamesD87 Rough Start And High Idle SN95 4.6L Mustang Tech 5
fiveoho Cold Start - Rough Idle And Blue Smoke ? SN95 4.6L Mustang Tech 1
tca7291 Engine Low/rough Idle At Warm Start Fox 5.0 Mustang Tech 5
jcgafford Engine High Idle, Rough Start Fox 5.0 Mustang Tech 101
M Hard to start, rough idle, battery light SN95 4.6L Mustang Tech 13
Smeech Dad's 5.4L F-150.. hard starts, high idle, rough idle... IAC? 1996 - 2004 SN95 Mustang -General/Talk- 0
L Rough Idle At Start Up Fox 5.0 Mustang Tech 2
Unreal281 Rough idle....stalling....not starting.... SN95 4.6L Mustang Tech 10
I rough idle, wont start when warm Fox 5.0 Mustang Tech 12
8 A possible solution for anyone having rough idle/cold start problems Fox 5.0 Mustang Tech 0
brentwoodboy Car runs rough at idle, smooth in higher RPMs. If it is shut off, won't start back.. 1994 - 1995 Specific Tech 12
T Rough Idle, terrible cold starts Fox 5.0 Mustang Tech 20
RacEoHolic330 Rough idle at start-up and white smoke after AFR 165 install Fox 5.0 Mustang Tech 5
R Engine My 95 gt idling rough 1994 - 1995 Specific Tech 5
MSTNGGRL1995 Rough, loping idle and random attempts to die 1994 - 1995 Specific Tech 1
Xenogenesis Engine Idles rough, misfires at idle, smells rich, but codes say it's lean on both banks SN95 V6 Mustang Tech 9
S Installed new intake and now car idles rough and turns off 1996 - 2004 SN95 Mustang -General/Talk- 7
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
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 Just arrived with a 1965 289 and a 1973 Mach I - and a vacuum leak solved The Welcome Wagon 1
N Engine Rough idle Fox 5.0 Mustang Tech 1
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
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
L 88 gt rough idle smell of fuel white smoke out of exhaust Fox 5.0 Mustang Tech 13
H Mustang running rough 1996 - 2004 SN95 Mustang -General/Talk- 3
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
M Engine Foxbody 5.0L idling rough/backfires after HCI swap Fox 5.0 Mustang Tech 3
9 Help with random rough idle 1994 - 1995 Specific Tech 5
J rough idle and very slight miss SVT Tech Forum 2
A 98 GT 4.6L SOHC Rough Idle/ Misfire (Vacuum Leak) Help Please. 1996 - 2004 SN95 Mustang -General/Talk- 4
P Engine 2002 mustang V6 rough idle in gear at low RPMs SN95 V6 Mustang Tech 2
9 Need Help with a Rough Idle/Coolant Loss Problem SN95 V6 Mustang Tech 3
I 96 Mustang V6 Help SN95 V6 Mustang Tech 0
F Engine Need Help Tracking A Rough Idle On 2003 V6, Not Iac Valve. SN95 V6 Mustang Tech 2
C Rough Idle Runs Rich No Codes Fox 5.0 Mustang Tech 10
S 99 V6 Mustang Loss Power Rough Idle And Drive SN95 V6 Mustang Tech 0
Whitecobrafox13 1990 Cobra Idling Erratically Fox 5.0 Mustang Tech 32
T 89 5.0l Iac Valve Operation Fox 5.0 Mustang Tech 7
Similar threads