• Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-

I have an odd misfire

  • Thread starter Thread starter Vyper202
  • Start date Start date Feb 24, 2021
V

Vyper202

Member
Jul 8, 2019
36
17
18
Virginia
Feb 24, 2021
#1
  • Feb 24, 2021
  • #1
OK guys, heres whats happening... 1998 GT, auto... all bone stock, 102K miles. I was checking under the hood Monday, oil, water etc... I noticed #2 injector had fuel puddled around it. It appeared the fuel rail bolts had loosened up enough to let the rail raise a bit and #2 was leaking from the top oring. OK, no big deal, i will just tighten the rail bolts I said. When i did I noticed a cut piece of oring on the injector body. Loosened the rail bolts, popped the rail up enough that #1 & #2 were out, pulled off #2 and replaced the oring with a spare I had. All went back together well, fired it up, no leaks, but idled rough, thought still has air that has to bleed. Took it down the road, I could feel the miss and it flashed a CEL. Get back, check under hood, everything is dry, nothing left unplugged, all looks good. Then i scanned it, misfire on cyl3???WTH??? Checked plug on #3 injector, plugged in solid. Got my meter and checked resistance, all were at 12.3. Pulled #3 plug, looked good, right color. Fired it up, put the trusty long screwdriver to my ear, all injectors clicking and firing, but still could feel a little miss. Took it back up the road, hard miss under load, CEL again, scan again, misfire on #3. Repeat all the above checks, everything still looks good.
So before I buy a replacement #3 injector, does anyone have any insight on anything else it may be before I pull it apart again? Thanks
 

Adieu

Easy there, this ain't a dating site.
20+ Year Stangneter
Mar 7, 2002
9,531
5,187
224
Feb 24, 2021
#2
  • Feb 24, 2021
  • #2
Vyper202 said:
OK guys, heres whats happening... 1998 GT, auto... all bone stock, 102K miles. I was checking under the hood Monday, oil, water etc... I noticed #2 injector had fuel puddled around it. It appeared the fuel rail bolts had loosened up enough to let the rail raise a bit and #2 was leaking from the top oring. OK, no big deal, i will just tighten the rail bolts I said. When i did I noticed a cut piece of oring on the injector body. Loosened the rail bolts, popped the rail up enough that #1 & #2 were out, pulled off #2 and replaced the oring with a spare I had. All went back together well, fired it up, no leaks, but idled rough, thought still has air that has to bleed. Took it down the road, I could feel the miss and it flashed a CEL. Get back, check under hood, everything is dry, nothing left unplugged, all looks good. Then i scanned it, misfire on cyl3???WTH??? Checked plug on #3 injector, plugged in solid. Got my meter and checked resistance, all were at 12.3. Pulled #3 plug, looked good, right color. Fired it up, put the trusty long screwdriver to my ear, all injectors clicking and firing, but still could feel a little miss. Took it back up the road, hard miss under load, CEL again, scan again, misfire on #3. Repeat all the above checks, everything still looks good.
So before I buy a replacement #3 injector, does anyone have any insight on anything else it may be before I pull it apart again? Thanks
Click to expand...
Swap your coil packs and see if the misfire moves to the other bank. You can also swap plugs between that cylinder and another to the same effect.
 
V

Vyper202

Member
Jul 8, 2019
36
17
18
Virginia
Feb 24, 2021
#3
  • Feb 24, 2021
  • #3
Yes Id planned on that this weekend thanks... Its just odd that #2 had the leak issue and now #3 is the miss....
 

Adieu

Easy there, this ain't a dating site.
20+ Year Stangneter
Mar 7, 2002
9,531
5,187
224
Feb 24, 2021
#4
  • Feb 24, 2021
  • #4
Vyper202 said:
Yes Id planned on that this weekend thanks... Its just odd that #2 had the leak issue and now #3 is the miss....
Click to expand...
Crazy stuff happens on cars. I worked on a 2018 M5 today that was just in the shop two days ago for an evap system repair. That was fixed, on the other end of the freaking car, by another tech. Today it comes back because it's stalling on cold start and I figured out it had two bad fuel pressure sensors (wasn't throwing codes, but the were reading at 6.0bar and 8.3bar without any fuel in the rails).

Sometimes it's more like playing whack-a-mole than it is fixing things.
 
V

Vyper202

Member
Jul 8, 2019
36
17
18
Virginia
Feb 24, 2021
#5
  • Feb 24, 2021
  • #5
Yes I agree.... I work on the mustangs almost as much as my BMW's..... LOL
 

McFly2

Member
Nov 21, 2020
68
11
18
Cincinnati
Feb 25, 2021
#6
  • Feb 25, 2021
  • #6
Just maybe when fuel rail was lifted; some debris got into #3 injector. Consider the injector swap when convenient.
 
V

Vyper202

Member
Jul 8, 2019
36
17
18
Virginia
Mar 1, 2021
#7
  • Mar 1, 2021
  • #7
OK guys, it was a couple of things if anyone else has this issue. Replaced the #3 injector, swapped #3 and #1 plugs, still had a little miss. Inspected the #3 plug boot and found a pinhole in rubber boot. It had carbon trace around the hole so I wrapped it a few times with electrical tape and it cured the miss. Now to get a new set of wires....
 
Reactions: McFly2
You must log in or register to reply here.

Similar threads

A
Check Engine codes jumping around
  • azactor
  • Jan 9, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
1
Views
178
1996 - 2004 SN95 Mustang -General/Talk- Jan 10, 2026
gkomo
96 GT 4.6 w/ dirty spark plug well
  • Mustang Momma
  • Apr 7, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
3
Views
120
1996 - 2004 SN95 Mustang -General/Talk- Apr 9, 2026
LILCBRA
M
01 mustang 3.8 fuel pressure issue
  • Mhaley2006
  • May 29, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
122
1996 - 2004 SN95 Mustang -General/Talk- May 29, 2026
Mhaley2006
M
M
Help! 2003 GT misfire when hot
  • Modular03
  • Feb 10, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
374
SN95 4.6L Mustang Tech Feb 13, 2026
Mustang5L5
R
Misfire at high rpm! Help
  • Ryanm2018gt
  • Jan 2, 2026
  • 2015 - 2023 (S550) Mustang -General/Talk
Replies
9
Views
936
2015 - 2023 (S550) Mustang -General/Talk Jan 17, 2026
highplace11
H
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
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?