• Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech

!!!Help!! Acceleration Problem!!

  • Thread starter Thread starter SC'D_96_COBRA
  • Start date Start date Jan 3, 2009

SC'D_96_COBRA

New Member
Aug 10, 2008
14
0
0
Los Angeles,CA
Jan 3, 2009
#1
  • Jan 3, 2009
  • #1
I have a problem. My car has trouble getting into high RPM's. The car accelerates through the RPMS fine on first gear, but on second gear when it start getting close to 4000 rpms my car feels like all power is lost. I shift to third it accelerates fine until the higher RPMs and it repeats the same as second gear.

Yesterday I kept the pedal stomped all the way to the ground to see if the RPMs would eventually raise and it did slightly but then it would get stuck again. It never let me get to red line. When I had my pedal to the ground i was looking through my rear view mirror and i saw a large fire ball come out. That scared me so I turned off the car and let it cruise to a stop.

I drove my car back home a few miles and I didnt feel anything abnormal. As of today I have been driving my car and I dont feel anything weird in idle or when driving like a grandma. The problem is only at high RPMS. I noticed also that I can get to High RPM's but only with the throttle slowly being increased.

Any ideas or suggestions would be really appreciated.
 

trinity_gt

10 Year Member
Jan 31, 2003
3,125
81
99
Canada
Jan 3, 2009
#2
  • Jan 3, 2009
  • #2
Ignition system would be my first suspicion. The "large fire ball" is evidence that the fire isn't getting lit under those conditions -- high RPM, WOT -- and raw fuel is accumulating in the exhaust waiting to be lit.

Plugs, wires, crank sensor, coils etc. Check it all.
 

the98stang

Active Member
Aug 12, 2005
2,408
0
47
Clovis, CA
Jan 3, 2009
#3
  • Jan 3, 2009
  • #3
Are you sure the RPM's stopped rising? Because if the RPMs rise but you don't gain any speed it's the clutch that's going out. Otherwise I would agree with above and start with the spark plugs, wires, etc.
 

MaxedGT

Member
Mar 31, 2005
304
0
17
Surrey BC Canada
Jan 3, 2009
#4
  • Jan 3, 2009
  • #4
start with replacing the fuel filter
 

joshjwc9

Active Member
Jun 12, 2006
1,095
17
39
Palm Harbor, FL
Jan 3, 2009
#5
  • Jan 3, 2009
  • #5
MaxedGT said:
start with replacing the fuel filter
Click to expand...
Then check plugs...
 
B

blubullett

Member
Jun 22, 2006
535
6
18
Modesto, CA
Jan 3, 2009
#6
  • Jan 3, 2009
  • #6
Supercharged engines are really sensitive to older plugs. I would try that first. When they start getting older it will miss in the higher rpms.
 
2

2002BLGT

Well-Known Member
Dec 18, 2003
2,945
4
59
Bedford VA
Jan 4, 2009
#7
  • Jan 4, 2009
  • #7
belt slip maybe ? watch the boost gauge and see if it flutters at all
 

SC'D_96_COBRA

New Member
Aug 10, 2008
14
0
0
Los Angeles,CA
Jan 4, 2009
#8
  • Jan 4, 2009
  • #8
Thanks alot guys for all the ideas. I dont think my clutch is slipping because i belive the RPM's would surge all the way to red line with full throttle if it were.

2002BLGT what other symptoms would a belt slip show??

Tommorow the first thing im going to buy are new spark plugs and wires. I have NGK iridium spark plugs in my engine. Do you guys think this is OK or are there any other suggestions for my supercharged application?

If anyone has anymore ideas please post your message it will be realy helpful.
 

MaxedGT

Member
Mar 31, 2005
304
0
17
Surrey BC Canada
Jan 4, 2009
#9
  • Jan 4, 2009
  • #9
Check and replace fuel filter!
joshjwc9 said:
Then check plugs...
Click to expand...

 

twogts4us

15 Year Member
Apr 1, 2004
4,188
12
79
Dunedin, FL
Jan 5, 2009
#10
  • Jan 5, 2009
  • #10
Fuel filter - easier, less expensive and more likely the culprit.
 

SC'D_96_COBRA

New Member
Aug 10, 2008
14
0
0
Los Angeles,CA
Jan 5, 2009
#11
  • Jan 5, 2009
  • #11
Thanks alot guys for all the Info. I changed the spark plugs today(technically yesterday) and that solved the problem. I change my spark plugs from NGK Iridium to NGK Tr6. I will not bad mouth the iridium plugs because i think they were gapped incorrecly. When i measured them they were gaped .05.

I gapped the TR6 to 0.032 and that seemed to do the trick.
 

flstang65

10 Year Member
Dec 6, 2007
1,484
135
94
SE Georgia
Jan 5, 2009
#12
  • Jan 5, 2009
  • #12
i would still do the fuel filter though
 
N

nizzo

New Member
Dec 23, 2008
39
0
0
Jan 5, 2009
#13
  • Jan 5, 2009
  • #13
could be valve springs i knew a guy had the same problem at 3500 rpms, turned out he needed valve springs
 
You must log in or register to reply here.

Similar threads

J
Lack of power on acceleration
  • jameshernandez
  • Aug 30, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
3
Views
94
1996 - 2004 SN95 Mustang -General/Talk- Sunday at 6:08 PM
jameshernandez
J
8
Foxbody high rpms and surging rpms
  • 86foxseth
  • Jun 9, 2026
  • Fox 5.0 Mustang Tech
Replies
4
Views
235
Fox 5.0 Mustang Tech Jun 13, 2026
Noobz347
Ford truck engine swap issues
  • keel
  • Jul 7, 2026
  • Other Auto Tech
Replies
17
Views
459
Other Auto Tech Jul 13, 2026
General karthief
B
Acceleration Vibration
  • Blown02svt
  • Dec 31, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
13
Views
668
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jan 5, 2026
General karthief
2000 GT-Front Brakes Not Releasing
  • stormsedge
  • Aug 7, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
5
Views
132
1996 - 2004 SN95 Mustang -General/Talk- Aug 7, 2026
Bronco2fan
B
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang 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?