• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific Tech

Codes 311, 314 throwing a C/E Light

  • Thread starter Thread starter Austin112701
  • Start date Start date Mar 23, 2021
A

Austin112701

New Member
Mar 23, 2021
6
0
1
Indiana
Mar 23, 2021
#1
  • Mar 23, 2021
  • #1
Removed smog pump, now car is throwing codes 311 and 314. Also check engine lights on and aggressively blinking at me any help would be greatly appreciated
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,260
17,945
224
Massachusetts
Mar 23, 2021
#2
  • Mar 23, 2021
  • #2
I assume a 94-95?

those codes pertain to the air injection system

OBD-I Diagnostic Trouble Code - Ford 3-Digit Codes - The Ranger Station

This page contains the 3-digit trouble codes that may be found when troubleshooting EEC-IV / OBD-I vehicles.
www.therangerstation.com

Blinking CEL is a bad misfire
 
A

Austin112701

New Member
Mar 23, 2021
6
0
1
Indiana
Mar 23, 2021
#3
  • Mar 23, 2021
  • #3
My bad, it’s a sn95. What would you suggest to do for the misfire?
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,260
17,945
224
Massachusetts
Mar 23, 2021
#4
  • Mar 23, 2021
  • #4
Check your plugs, cap, rotor and wires.
 

Chythar

Recently finished repairing my rear
20+ Year Stangneter
Aug 26, 2004
2,373
140
113
Foothill Ranch, CA
Mar 24, 2021
#5
  • Mar 24, 2021
  • #5
311 and 314 came up because you removed the smog pump, so air isn't getting pumped past some of the emissions controls. To permanently get rid of those codes, you'll need to get a chip for the engine computer that eliminates those checks. There are some other DIY ways of eliminating the codes, but I don't know them offhand.

When you removed the smog pump, did you remove anything else? Did you yank against any of the plug wires, or maybe smack a wrench into one of the spark plugs? That's one reason why Mustang5L5 said to check them. If you can't find anything, I'd recommend putting the smog pump back on temporarily and see if anything changes.Maybe another code will pop up once the 311 and 314 clear.
 
A

Austin112701

New Member
Mar 23, 2021
6
0
1
Indiana
Mar 24, 2021
#6
  • Mar 24, 2021
  • #6
Mustang5L5 said:
Check your plugs, cap, rotor and wires.
Click to expand...
Anything specific I should look for while checking these things?
 
A

Austin112701

New Member
Mar 23, 2021
6
0
1
Indiana
Mar 24, 2021
#7
  • Mar 24, 2021
  • #7
Chythar said:
311 and 314 came up because you removed the smog pump, so air isn't getting pumped past some of the emissions controls. To permanently get rid of those codes, you'll need to get a chip for the engine computer that eliminates those checks. There are some other DIY ways of eliminating the codes, but I don't know them offhand.

When you removed the smog pump, did you remove anything else? Did you yank against any of the plug wires, or maybe smack a wrench into one of the spark plugs? That's one reason why Mustang5L5 said to check them. If you can't find anything, I'd recommend putting the smog pump back on temporarily and see if anything changes.Maybe another code will pop up once the 311 and 314 clear.
Click to expand...
I removed the line to the back of the heads, cut and flipped the connections to seal said heads, would this cause similar issues if I didn’t seal the heads properly? plugged a green vacuum line that runs to the tab/tad. I also figured that’s why those codes were being thrown(just didn’t know if anyone would have advice)
 

Chythar

Recently finished repairing my rear
20+ Year Stangneter
Aug 26, 2004
2,373
140
113
Foothill Ranch, CA
Mar 24, 2021
#8
  • Mar 24, 2021
  • #8
The smog pump supplies oxygen to the catalytic converters; through the head when the engine is cold, and directly to the exhaust when warm. Here's a great post from jrichker that explains it better then I can:

Engine - 1995 gt thermactor question

I have a set of GT40 heads from a 97 Mountaineer but they don't have the thermactor holes. I'm wondering if I can reroute those thermactor tubes to somewhere just behind the collectors on the headers. Maybe weld in a bung so that I can thread those tubes in, So they don't throw a check engine...
www.stangnet.com

If the plugs on the back of the head aren't sealed and are letting in unmetered air, it shouldn't affect the spark plugs but the O2's might see the exhaust as lean and cause the computer to add too much fuel to richen it back up.

The green plastic hose is from a different system, and hooks up to the EGR. That would be a different issue. The red hose supplies engine vacuum to the rest of the emissions parts, including the EGR. If you've got a broken hose (the plastic gets really brittle with age), that's more unmetered air in the system. Unhook the red hose from the intake and cap the nipple off, and see if that changes things.

A general bit of knowledge on 90's era Fords - The computer can adapt fuel flow to hide some issues, and sensors can report wrong values instead of failing outright. So it's rare to point to one thing that's causing all of your issues. It's likely several smaller issues combined together. This is why most help here will be of the type "try this, and report back your results". And this is with a stock system, which you've modified by removing the thermactor system. That's not necessarily a bad thing, but it can make diagnosis more difficult.
 
Reactions: General karthief
A

Austin112701

New Member
Mar 23, 2021
6
0
1
Indiana
Mar 25, 2021
#9
  • Mar 25, 2021
  • #9
Chythar said:
The smog pump supplies oxygen to the catalytic converters; through the head when the engine is cold, and directly to the exhaust when warm. Here's a great post from jrichker that explains it better then I can:

Engine - 1995 gt thermactor question

I have a set of GT40 heads from a 97 Mountaineer but they don't have the thermactor holes. I'm wondering if I can reroute those thermactor tubes to somewhere just behind the collectors on the headers. Maybe weld in a bung so that I can thread those tubes in, So they don't throw a check engine...
www.stangnet.com

If the plugs on the back of the head aren't sealed and are letting in unmetered air, it shouldn't affect the spark plugs but the O2's might see the exhaust as lean and cause the computer to add too much fuel to richen it back up.

The green plastic hose is from a different system, and hooks up to the EGR. That would be a different issue. The red hose supplies engine vacuum to the rest of the emissions parts, including the EGR. If you've got a broken hose (the plastic gets really brittle with age), that's more unmetered air in the system. Unhook the red hose from the intake and cap the nipple off, and see if that changes things.

A general bit of knowledge on 90's era Fords - The computer can adapt fuel flow to hide some issues, and sensors can report wrong values instead of failing outright. So it's rare to point to one thing that's causing all of your issues. It's likely several smaller issues combined together. This is why most help here will be of the type "try this, and report back your results". And this is with a stock system, which you've modified by removing the thermactor system. That's not necessarily a bad thing, but it can make diagnosis more difficult.
Click to expand...
Thank you so much with your response sir! It gives me a lot to think about... I sadly won’t have time till this weekend to check things out, but will report back with any info I can provide! Thank you so much for your time
 
R

rockyracoon

10 Year Member
Nov 23, 2005
874
27
49
margate NJ
Apr 3, 2021
#10
  • Apr 3, 2021
  • #10
I've got 311 and 314 since I have the thermactor system partially disabled. I'm still running air to the cats but not to the back of the heads as my heads are not drilled for the passages. My 311 and 314 codes are present but do not illuminate the light. Are you sure there isn't another code present ?
 
You must log in or register to reply here.

Similar threads

6
Been dealing with this issue for years on my 94 GT
  • 66gt94gt05gt
  • Jul 24, 2024
  • 1994 - 1995 Specific Tech
  • 2
Replies
21
Views
2K
1994 - 1995 Specific Tech Aug 31, 2024
AeroCoupe
L
95 gt engine vibration
  • lenzgt
  • May 11, 2026
  • 1994 - 1995 Specific Tech
Replies
6
Views
221
1994 - 1995 Specific Tech May 26, 2026
lenzgt
L
D
Boss 302 cel
  • dstrong2012kona
  • Oct 31, 2025
  • 2005 - 2014 S-197 Mustang -General/Talk-
Replies
1
Views
133
2005 - 2014 S-197 Mustang -General/Talk- Oct 31, 2025
Mcmahst
D
  • Locked
Boss 302 cel
  • dstrong2012kona
  • Oct 31, 2025
  • 2005 - 2014 S-197 Mustang -General/Talk-
Replies
1
Views
117
2005 - 2014 S-197 Mustang -General/Talk- Oct 31, 2025
Noobz347
W
2003 Mustang GT issues
  • westberry23
  • Aug 25, 2025
  • SN95 4.6L Mustang Tech
Replies
5
Views
311
SN95 4.6L Mustang Tech Sep 24, 2025
squeak93
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific 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?