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

P0301 Mil Code???

  • Thread starter Thread starter Jason2000GT
  • Start date Start date Jan 26, 2004

Jason2000GT

Founding Member
Aug 14, 2002
90
0
0
Glendale, AZ
Jan 26, 2004
#1
  • Jan 26, 2004
  • #1
Here is my stituation:

I installed new Autolite 764 plugs on 1/19. The car ran fine on 1/20 and then the evening on 1/21, I noticed a very rough idle and it felt like the car was stumbling when taking off normaly in 1st gear until like 2000 rpms.

After driving it a few more times, I finally got a MIL light. Ran down to Autozone and it was a P0301 - cylinder #1 misfire code. When I got home and car had cooled off, I put the stock plug back in the car. That was the evening on 1/23. I drove it to work this morning(1/26), and I am feeling the same stumbling in low rpms in 1st gear. Once the car gets up to normal operating temp, it seems to go away. Went to lunch and it was running ok, but the idle was still kinda rough. I left my parking garage and drove for about 5mins over to Borders. Came out of Borders after 15mins and the car was stumbling in 1st gear.

I am thinking about switching out all my plugs to my old stock plugs to see if that resolves the problem. If that does, I will go and get some Motorcraft AWFS-22Cs and see what happens.

Any suggestions?
 

KaPPaBaLL

New Member
Nov 28, 2003
1,326
0
0
BAYAREA
Jan 26, 2004
#2
  • Jan 26, 2004
  • #2
your first problem sounds like your new plug was defective. The second problem is that you're running an old platinum plugs with your new Copper plugs. It'll bogg like that when you have 7 of the same plugs and 1 odd one...

go back to the autozone and buy another 764's autolite plug and change the old one out..
 

Jason2000GT

Founding Member
Aug 14, 2002
90
0
0
Glendale, AZ
Jan 26, 2004
#3
  • Jan 26, 2004
  • #3
Yeah, i am going to change out my old stock one when i get home tonight. Hopefully, that will clear up the problem. I will repost what I find out. Thanks!!!
 

KaPPaBaLL

New Member
Nov 28, 2003
1,326
0
0
BAYAREA
Jan 26, 2004
#4
  • Jan 26, 2004
  • #4
just hope you didn't cross thread the spark plug. Use a little little bit of anti-seize as well.
 
N

NOSInjected00GT

New Member
Sep 7, 2003
34
0
0
Jan 26, 2004
#5
  • Jan 26, 2004
  • #5
code p0301 is a cylinder 1 misfire... probably not the plugs... u need to probably change the coil on cylinder 1
 

PDubs

Founding Member
Feb 15, 2002
1,138
0
36
Always farging hot in Texas
Jan 26, 2004
#6
  • Jan 26, 2004
  • #6
Jason2000GT said:
I noticed a very rough idle and it felt like the car was stumbling when taking off normaly in 1st gear until like 2000 rpms.

After driving it a few more times, I finally got a MIL light. Ran down to Autozone and it was a P0301 - cylinder #1 misfire code....I am feeling the same stumbling in low rpms in 1st gear.
Click to expand...

All signs point to bad coil pack. I had the exact same indicators on mine when I had the GT, and the new coil pack solved it. Your plugs should be fine.
 

Jason2000GT

Founding Member
Aug 14, 2002
90
0
0
Glendale, AZ
Jan 27, 2004
#7
  • Jan 27, 2004
  • #7
I replaced the #1 cylinder plug with a brand new Autolite 764 last night. I also visually inspected the coil-on-plug adapter and I blew out any debri with some compressed air. Put everything back together and started the car. It idled good for about 8 minutes then I shut it off and called it a night.

This morning on the way to meet some guys for breakfast, it ran fine for about 15mins, then it just started acting up again. Very bad hesitation, felt like it was misfiring or I had some bad gasoline or something. On the way to work, it ran the worst it ever has since I changed my plugs. My idle was even staying at 1200 rpms when the clutch was depressed at a stop light. Not sure if that was from the cold weather (38-40 degrees) or not.

I think I am going to put all my stock plugs back in the car and test that. If it still runs bad, I guess I will have to look else where.

Does anyone know how to test a coil-on-plug device? Maybe one of my coil-on-plug devices went south when I was changing the plugs. I can't think of anything else and this all started after I changed to Autolite 764s. Do some cars not like the 764s???

Any input?
 

KaPPaBaLL

New Member
Nov 28, 2003
1,326
0
0
BAYAREA
Jan 27, 2004
#8
  • Jan 27, 2004
  • #8
crap bro. it could be just the COP that went back. my autolites are fine. i know many that run it without problems. a new COP is $50 at Pepboys. Ask for the 2000+ F150 COP.
 
You must log in or register to reply here.

Similar threads

M
Help! 2003 GT misfire when hot
  • Modular03
  • Feb 10, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
310
SN95 4.6L Mustang Tech Feb 13, 2026
Mustang5L5
K
Engine 2000 Mustang GT - Fuel issue post-blown spark plug repair
  • kenster1092
  • Feb 26, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
283
SN95 4.6L Mustang Tech Mar 10, 2026
kenster1092
K
S
idles perfect then jolts and cuts out when put into Reverse or Drive.
  • shanesstangs
  • Mar 12, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
4
Views
178
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Apr 27, 2026
General karthief
P
2002 T5 transmission vibration issue
  • puffoo
  • Feb 22, 2026
  • SN95 V6 Mustang Tech
Replies
0
Views
141
SN95 V6 Mustang Tech Feb 22, 2026
puffoo
P
A
Rough idle - cylinder 1 and 6 misfire HELP
  • austindavies935
  • Jul 24, 2025
  • SN95 4.6L Mustang Tech
Replies
12
Views
632
SN95 4.6L Mustang Tech Jul 24, 2025
gkomo
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?