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

Codes and d**n codes

  • Thread starter Thread starter RemoW2112
  • Start date Start date Nov 4, 2010
R

RemoW2112

New Member
Apr 18, 2005
21
0
1
Nov 4, 2010
#1
  • Nov 4, 2010
  • #1
Back to the 95 I just got.
I have the cats bolted back on, new o2 sensors, fixed the stripped bolt hole on the intake for the upper intake bolt, new gasket for upper intake, plugs, wires, cap, rotor, #19 injectors, and an MSD coil.

Mods that I know about:
x302 heads
e303 cam
93 Cobra intake
K&N air filter
Trick flow elbow
BBK shorty headers

Car still won't idle right. It is loping at idle and surging a little bit. You can feel what I would describe as a miss up to 2k. I ran codes last night and get the following: KOEO 511, KOER 172, 136.

I don't believe the car has a chip in it. How do I check? From the research and searching I have done the engine seems to be using a value table instead of reading the O2 sensors to determine mixture. I have not found a definitive answer on how to fix the 172, 136 codes.

The EGR is disconnected from the exhaust but the EGR is still attached and hooked up to the throttle body. I capped the threaded end on the engine and EGR. I get no CEL light.

I have tried all the recommended items to even out idle. Clean the MAF, throttle body, etc. I have not messed with the TPS since it supposed to not need adjustment on 94-95 engines.

I am at a loss as what to try next, with the way the engine is idling there is no way it will pass emmisions. On an old school car I would swear I have a massive vacuum leak but if I do I can't find it.

Any suggestion on where I go from here?

Thanks all,
Dan...
 

final5-0

Mustang Master
Apr 6, 2003
6,817
12
79
DFW Texas
Nov 4, 2010
#2
  • Nov 4, 2010
  • #2
511 tells you something is stuck in the service port of the pcm

Grady
 

Chythar

Recently finished repairing my rear
20+ Year Stangneter
Aug 26, 2004
2,373
140
113
Foothill Ranch, CA
Nov 4, 2010
#3
  • Nov 4, 2010
  • #3
The 94-95 computers are less flexible to engine mods than pre-94 computers. It really depends on the mods and how they all work together, but I've also heard of many idle issues with the Ford alphabet cams (b, e, etc). You may not be able to get a smooth idle unless you put a chip in the computer.

If I remember how the computer works, it always uses lookup tables based on sensor input. The O2 sensors come into play once the engine warms up, so the computer can balance the air/fuel mixture. Don't know if the O2's are used as inputs with the other sensors, or just a double-check to see if its lean, rich or just right. I can tell you that the a/f mix will obviously be off, since the lookup tables don't properly reflect the engine mods.

I'm guessing that the computer was able to adapt the fuel flow to get good results from the O2's, but it had to add fuel to compensate for the extra air flow from your mods. That's my guess on the error codes you have. Someone please correct me if my presumption is wrong.
 

toyman

10 Year Member
Jul 19, 2007
1,944
54
79
Vernon BC
Nov 5, 2010
#4
  • Nov 5, 2010
  • #4
final5-0 said:
511 tells you something is stuck in the service port of the pcm

Grady
Click to expand...

That may be too subtle. To check if there is a chip you need to pull the ECU and see if one is installed in the service port. Code 511 is a read only memory test failure.
 
You must log in or register to reply here.

Similar threads

L
95 gt engine vibration
  • lenzgt
  • May 11, 2026
  • 1994 - 1995 Specific Tech
Replies
6
Views
120
1994 - 1995 Specific Tech May 26, 2026
lenzgt
L
Engine 95 GT and 95 Cobra sensors and TB gasket
  • Sonic
  • Dec 21, 2025
  • 1994 - 1995 Specific Tech
Replies
1
Views
299
1994 - 1995 Specific Tech Dec 23, 2025
WhiteCobra95
Tuners come on inside
  • squeak93
  • Feb 13, 2026
  • SVT Tech Forum
Replies
1
Views
213
SVT Tech Forum Feb 20, 2026
squeak93
2
Running very very rich
  • 2esoteric
  • Oct 31, 2025
  • Fox 5.0 Mustang Tech
Replies
4
Views
303
Fox 5.0 Mustang Tech Oct 31, 2025
Noobz347
S
Fuel ‘88 GT Runs Rich Cold — Fixes Itself When I Unplug Sensors (ECT, MAF, O2, etc.)
  • Sufarry
  • Nov 6, 2025
  • Fox 5.0 Mustang Tech
Replies
12
Views
703
Fox 5.0 Mustang Tech Nov 9, 2025
Mustang5L5
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?