Hi everyone, I am new to the forum so please excuse me if I have posted this question in the wrong place.

-About 6 months ago at bout 85k miles I replaced my clutch
-After the replacement I have had a rough idle, especially under load (w/ ac on)
-No codes were on but I did try replacing my fuel filter and air filter. I also cleaned all the sensors in the throttle body with electronic duster. I did wipe the throttle body but it was clean.
-The problem of a rough idle has persisted but without the ac on the car ran normal
-Now I have 95k miles and the check engine light just went on
-I have noticed the black carbon on my exhaust, suggesting my fuel mixture is running rich

Anybody have advise on what to do next?

Thanks in advance for any help, much appreciated

 

Go to a auto parts store like auto zone and have them scan your car, and get the code it threw. Then come back here and someone should be able to help you out.

 

Ok, thanks. I'll get the code that tripped in the morning and report back.

 

I got the codes;

B2103
P0171
P0174

Strangly enough looks like its running lean. Should I start by thrown smoke through the system to see if there are any leaks? What if I don't find any leaks, what are the other possibilities?

 

First is likely unrelated. PATS related it looks like. Unless it's dieing randomly and flashing the anti-theft symbol.
B2103 9232 Antenna Not Connected - Defective Transceiver

As for further possibilities for the 2 bank lean codes, don't know, sure others will have other things to check/replace aside from hoses and the like.

 

based on your description of events leading up to the rough
running, i have to go with an oxygen sensor issue. if all you did
was drop the transmission, do the clutch work, then raise it
again the only thing that could have got disturbed really is the
wiring harness. i'd look over the oxygen sensor wiring (mainly the
front sensors) to make sure there is no pinching or burning or
any other abnormality. also front connectors going front, rears
going rear....


the PCM may think the system is lean based on the oxygen sensor
feedback, but in reality the combustion in the cylinders may be rich
which explains the coating on your exhaust tips.

i don't see P2103 listed in the mustang DTC chart.

 

For FORD about the best it can be narrowed down to is:

 

ok thanks wayne613

 

Wow, thanks guys! So it looks like I have 2 problems.

1. B2103 Passive Anti-Theft System

The car has always randomly flashed the anti-theft symbol when locked. Never had any battery drainage problems, and that's the only code that came up. I am not sure what this means, would that code trip the check engine light? Is this how it should work and I should try a reset of the computer?

2. P0171 and P0174 Lean

Oxygen sensor makes sense the way you explain the conflicting physical evidence of it running rich, but the electronic evidence saying it's running lean. Ill check it out if I dont have the leaks obviously, but I've checked for leaks 6 months ago and found nothing so I anticipate I'll still wont find no leaks. I'll let you know how it works out. Thanks for the help.

 

Are you modded at all? Any chance you installed a CAI without a retune?

My first thoughts when I read your post was right in line with hammeron's thinking: O2 sensors/wiring.