Still Stuck in CEL hell

[EXPLORINGVA]

As a few of you will recall, i'm the one with code 41 showing up intermitantly. The TPS and O2 Sensor are new, plugs and wires are new. I took off the plug for the MAF and just cleaned the plug off (no maf codes as of yet) I also had the Ignition pack ohmed out, primary and secondarys both within specs. Also changed the fuel filter and cleaned out the throttle body. When I really get on the throttle i'm getting black crap (carbon?) coming out the tailpipe.
I'm about ready to go buy the for sale sign. This is driving me nuts. You Explorer Gods haven't let me down yet on here. I'm digging for ideas. Thanks alot guys.

 

[Positive Vibes]

What about the IAC or the FPRC or the PCV?

 

[EXPLORINGVA]

The PCV is fine, as far as the other two...wouldn't they throw off codes?

 

[MrShorty]

How consistently does the 41 come back? Every time you drive it or after several days? Does it show up in the KOER test? Have you checked fuel pressure? All wiring/connectors between the O2 sensor and PCM intact? Any vacuum leaks? Does the PCM have a good ground connection (essentially no voltage drop across the PCM ground)? Exhaust leaks?

 

[Positive Vibes]

The PCV is fine, as far as the other two...wouldn't they throw off codes?

Not necessarily, I was getting O2 codes and a couple more. The helpful people here led me to the problem. Was a dirty MAF and FPRC.

 

[Rhett]

Have you checked the fuel pressure regulator?

Your truck has the signs of a bad one...with the black smoke out the tailpipe when you get on it...

 

[EXPLORINGVA]

MR Shorty
The 41 usually shows up after i've been driving for a while in 5th gear for longer than 20 minutes after I stop at a light or something. As far as the KOER test goes, after I do the KOEO test nothing happens. I can't even get the scanner to ID the engine (3 blinks). According to the book the "engine running lean" has to be corrected before the KOER test can be accomplished. The fuel pressure and O2 sensor wires are fine, didn't see anything burnt on them or anything. HAven't seen or heard any vacuum leaks. The PCM seems to be grounded okay too. All I know as of now is i'm running like s*#! and can't figure it out. Much to my dis-pleasure, I think it may be time to visit the local FORD dealer and let them put a machine on it to figure out what th eproblem is. The only reason i'm apprehensive about doing that is that they probably won't find it either, then i'll be out another $100. I appreciate all the help!!!!

 

[Positive Vibes]

The PCV is fine, as far as the other two...wouldn't they throw off codes?

The ECM cant tell exactly what the problem is. Just cause the code leads towards the O2 sensor doesn't mean thats the problem, thats just where its reading a signal thats not in spec.

The parts we are recommending are fairly cheap and easy to install.

 

[MrShorty]

MR Shorty
The 41 usually shows up after i've been driving for a while in 5th gear for longer than 20 minutes after I stop at a light or something. As far as the KOER test goes, after I do the KOEO test nothing happens. I can't even get the scanner to ID the engine (3 blinks). According to the book the "engine running lean" has to be corrected before the KOER test can be accomplished. The fuel pressure and O2 sensor wires are fine, didn't see anything burnt on them or anything. HAven't seen or heard any vacuum leaks. The PCM seems to be grounded okay too. All I know as of now is i'm running like s*#! and can't figure it out. Much to my dis-pleasure, I think it may be time to visit the local FORD dealer and let them put a machine on it to figure out what th eproblem is. The only reason i'm apprehensive about doing that is that they probably won't find it either, then i'll be out another $100. I appreciate all the help!!!!

First misconception I see: "According to the book the "engine running lean" has to be corrected before the KOER test can be accomplished." Not sure why the book is giving you this impression. 41 is a continuous memory code, not a KOEO hard fault code. It's true that you should get all KOEO hard faults cleared so you get a '11' code for that portion of the KOEO test before running the KEOR test. However, it is better diagnostic practice to run and resolve any KOER codes before dealing with continuous memory codes. Even if you haven't got a KOEO hard fault pass code, you should be able to go through the motions of running the KOER test, it will just give you a KOER code 98 -- "didn't pass KOEO test." Next thing I would do is figure out the KOER test.
Due to the frustration level this is causing, it might be worth it to take it to someone else. One thing to note, as fancy as their "scanner" might be, it can't retrieve any more information from your old EEC-IV computer than you can with a jumper wire. Until ~'93, the EEC-IV computer wasn't set up with a real time data stream. All your computer can put out is trouble codes, which you already know how to read (as soon as you figure out the KEOR test).

 

[Josh]

I just had this problem on my truck. I installed a Pro-M MAF a couple of weeks ago and was having intermittant CEL's. If I reved the motor it would go away. I read that the ECM does not look at the O2 sensor until the sensor has warmed up to around 600 degrees. Hence the 20 minutes before the CEL comes on. Sooooooo, I replaced the the O2 sensor with a new one and BAM! CEL was back on and I was pissed! :fire: I decided to replace the MAF with my stock one just to see what would happen. I put it in and drove almost 300 miles with no problems. I too was getting the 41 error code. You should come down (To VB) and go to You Wrench It. You can pick up the housing and sensor for about 25 bucks and change it in the parking lot to see. I hope this helps.