Check Engine Light, Runnign Lean
 

Hey guys, Ive written a post similar to this one before. I didnt get a solid answer, partly due to my lack of information. I have a 1995 GT, long tubes, off road H, and CAI. I did a KOEO test and came up with three 3 digit faults:
181-Lean cond indicated @ part throttle / Front or Right o2 sesnor
189-Lean cond indicated @ part throttle / Rear or left o2 senso
332-EGR sensor not reading
111-System check good

I replaced the EGr sensor (not the valve), and tested the valve. The valve checked good, diaphragm functions as intended. I drove the car and reaccomplished the KOEO test, my 332 code is gone and hasnt resurfaced since. I still have a lean condition that I cannot figure out. I replaced my O2 sensors and checked my fuel pressure too. F/P is good with vaccuun connected and discon. I cant find anyone to help me solve my problem. Somewhere in the motor there is a sensor telling the computer my car is rich, thus leaning it out. I just cant find it. Is there too much EGR gas running throgh the motor?? That would make the computer sense a rich condition. The computer would then lean the mixture - right?? I dont know. Any help would be great. Thanks. Oh, just so its not suggested, the fuel filter has been changed three times in the past 3 months. That should rule out the filter.:mad:

not sure but did you extened the wireing on the o2 sensors or add a conector I cant remember but increasing the o2's length can mess readings up you have to extened the harness .

might not apply at all but something to look into.

O2 sensor wire harness extension
 

I did have to extend the 02 sensor wiring harness. I used the same guage wire, and the harness was extended approx 1ft on both sides. I didnt think about that as a potential problem, have you heard of other people having issues with this as well?? Is there a resistance problem here?? Do you know if there is a suitable extension length for the harness?

Surely someone has had a similar problem. I would really like to have some opinions here. Anything is better than me taking the car to the Ford service dept. They want $175 just to diagnose the prob. That seems a little crazy to me. God knows what it would cost to have them repair the problem.

Actually what codes 181 and 189 mean is that you have reached the adaptive fuel limit at part throttle. Simply put the computer cannot add more fuel than it is giving now at that fuel pressure. The solution is is an adjustable FP regulator if you don't already have one. Raise pressure 2 psi or so at a time and try it. I didn't have this happen until I added my heads, I had to buy an adjustable reg. You don't seem to have many mods that would warrant this, but obviously the computer can't compensate, so a raise in pressure is needed.

adaptive fuel limit
 

-fi347

The only question I have is why would a mostly stock GT run into this problem to begin with?? Is there a part of my fuel system that isnt up to par?? If I was having probs with my fuel injectors I would certainly get a code, right?? Just doesnt make sense I would run into this problen over a period of time, increasingly worsening. I'll try the FPR for now, but does anyone have any other suggestions? Thanks for the help

Yeah, that's what I was saying about not having enough mods to warrant needing that. But that's what those codes do mean. If there is a part of the fuel system not up to par, my first guess would be the fuel filter. The rest of the fuel system, pump, lines, fuel rails and injectors are more than enough for what you have right now.

Have you looked at the MAF sensor? Just a guess. When I added my CAI and unequal headers & new O2's it read it as lean. So put on an AFPR at 42 psi at idle still was lean. It was the filter oil had become baked on the sensor. Cleaned it with brake cleaner so not to break the little wires on the sensor and the light hasn't came on since. And it runs a ton better.

T hanks stangGT95. I will gove it a try. Hope it doesnt damage the MAF sensor. Dont want to cause more damage than good. I think I might go ahead with the adj FPR as well. Seems you have to have them if ya plan on anything more than a bolt on mod. I just want to find the solution to my prob so I can spend money on upgrades, not getting the car to run normally. Thanks for the help
:D

Just another thought...might want to think about getting a air/fuel gauge. Before I fixed the lean condition I put one on (it was a digital one) now when I do some future upgrades I'll at least have an idea of what's going on and maybe prevent some damage. Good luck with your car.

codes 181 and 189
 

Mattknight I am also having problems with check engine light and codes 181 and 189 (adaptive fuel). Di you fix your problem? How? It's driving me crazy! Email Jackzpcb@juno.com Anybody?!!!!

Good suggestion on the MAF - also check to see if you have a vacuum leak - that's what happened to my daughter's 99 Escort ZX2 with the same codes. Turned out to be a cracked EGR hose.

The things i'd look at, as mentioned, is the MAF sensor which the barometric pressure reading and actual airflow calculations are made by. Using a residueless spray like brake clean or even better is electrical contact cleaner should clean it out. You can usually tell when it's contaminated because it will be sooty, or black (most times).
I'd use brake clean and spray around your engine while it's running, if you hear a change in how it runs then you have a leak in that area you have to find.
Also, putting 02 sensors farther downstream will reduce their reading ability since they have to be at their operating temperature to read properly. The 02 heaters only stay on for a few minutes at startup, the rest is done by the exhaust heat.
Check your fuel pressure with and without the vacuum line on the fuel pressure regulator to determine if that's a possible problem. With it connected i believe it should be *around* 32-35 psi, with it disconnected 38-40 psi i believe (numbers off the top of my head). You should also drive it and see under load if fuel pressure drops, you may have a restricted fuel filter.
Does your car ping at all under any condition, that could give you a clue as to what's happening.
Good luck,

Just to clarify what 84LX89GT said - if you run a fuel pressure gauge while driving, fuel pressure wil vary with manifold vacuum from about 32#-40# which is normal. If you run at wide open throttle, fuel pressure should not drop off as rpm increases with the pedal to the floor.