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Actron scanner codes

My scanner is giving me codes 172 and 176. Since i bought the truck last year it would only run well on 93 octane, anything less would cause deiseling.
I've been told by many anything from fuel pump replacing to a bad coil or wires or bad o2 sensor(s) and last was to clean intake throttlebody which is a cheap fix and i will do in the morning. Any suggestions would be greatly appreciated. Thanks, MrMike
 

Skandocious

Post Whores Make Me Sick
19,076
655
California
Welcome to the site Mike! :wavey:

What engine are we working on? Dieseling is more common on carb'd engines so I'm assuming that's what it is?

As for the codes:

172 (KOER) HEGO sensor circuit indicates system lean (right side)
176 (Continuous Memory) HEGO sensor circuit indicates system lean (left side)

;)
 
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blacksnapon

Moderator
Staff member
vacuum leaks will cause lean codes as well.
 

smokey

Hitech hillbilly
Staff member
I'll go with a vaccuum leaks for those codes.
I would test the O2's before replacing no use throwing 100 bucks at the problem and not fixing it. when it may be as simple as a unplugged or a hole rubbed in a vacuum line.
 

CowboyBilly9Mile

Charter Member
7,118
442
USA
Weeeeeell, if ya have a lookie at the DTC's for 172 and 176, KOER, those are correctly noted as lean codes. But what hasn't yet been discussed until now is the fact that a whole bunch of the early 4.0's had lower intake bolts that lost preload (ie, torque) and as such developed vac leaks. Most of the time, simply retorquing the lower intake bolts cures the problem however a handful of folks actually will/did have to replace the gasket. By loose bolts, and I can tell you from personal experience on my 94 that I bought brand new in 94, those bolts just might be finger tight when you get in there and have a look. So on that note, go out there and spend the time retorquing them before doing anything else. While you are in there, inspect the PCV system for evidence of anything that will result in leakage; this includes a bad (stuck) PCV valve.

Rich mixtures burn cool and lean mixtures burn hot; this lends to explaining why you are having dieseling problems (although most people experience pinging). So on that note, if you are having pinging problems, the most common reasons are the lower intake gasket bolts being loose (and maybe bad gasket), the MAF sensor is dirty, which is fairly common and will *trick* the ECM into thinking there is less air flow that is actually occuring and will lean the mixture, or carbon buildup. I list these three tiems in no order of likelyhood in solving the problem. FWIW, Ford issued a TSB years ago about carbon buildup and how to address it. Basically, the OHV 4.0 is vulnerable to carbon build up and as we all know this encourages pinging and dieseling. There is a simple remedy for this and myself, I would use the Ford decarbon solution rather than the sea foam crap. It is also noted in the TSB that usage of gasoline with an octane higher than the recommended 87 actually promotes carbon buildup.

IMO, you have three common matters to look into, and they are all fairly simple to address. Finally, those O2 sensors back in 2002 cost $200; the dealer here told me they were nearly always regarded as life of vehicle parts. On that note, I'd react accordingly and address the three most common matters.

**One of those lower intake bolts is snotty to get to, IIRC it's in back; have a couple of swivels around before starting. Access to the front right side is a bit tight too.

*****If you go in there and spray the throttle body with cleaner a lot of that crud will land on your spark plugs. If it's real dirty and you use a bunch of cleaner it will then run crappy, surge/buck, be low on power, and get lousy mileage due to a weak spark compliments of the conductive nature of the crud. So on that note, you might strongly consider doing this when (or if) you decarbon the engine, which happens to generate the need for new plugs for the exact same reason. Finally, use throttle body safe cleaner and not carb cleaner as there is a coating on the throttle body that you don't want to dissolve and remove.
 
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smokey

Hitech hillbilly
Staff member
Good post Bill! those intake bolts do get loose and create a vacuum leak. the left rear is fun to get to will all on the engine.
If you ever have to replace the gaskets get Ford replacement ones the aftermarket ones just are not as good as the ford one's are.
 
Ok, I'm heading out to check for loose intake bolts. I also have throttle body cleaner which i will hold off on until i check the torque on the bolts. I thank you all for your input and will be back to let you know how it turned out.
Best regards, Mike
 
Fixed, but another question

Turns out my MAF sensor is shot. After a few hours of checking torque and searching for a bad or loose vaccuum line, i removed the complete air breather, cleaned and replaced, by accident i restarted it with the MAF sensor unplugged and it ran like a new truck. When i plugged in the MAF it went back to its old self, no power and much bogging. Needless to say, i again unplugged it and took a ride. My brother suggested i try 87 octane which i was hesitant to do but figured i'd try it. I put in $10 approx 6 gals and i was shocked that it ran so well. No more "pinging" and it ran like a raped ape. So my next question is......
How important is the MAF sensor? Do i have to replace it? Will it hurt my truck to run without it? I figure why throw $100+ away on something i don't think i need. Yeah, the check engine light stays on but i can live with that. I have to say a huge THANK YOU to you guys for leading me in the right direction. I hope you all have a safe and happy holiday season. Mr.Mike
 
Found problem but a quick follow up question

After alot of checking torque and searching for a bad vaccuum line with no success, i decided to start with the air cleaner and go from there. After removing, cleaning and replacing, i forgot to plug in my MAF sensor and when i started it up it ran like new. When i realized i missed the MAF and plugged it in it went back to it's old self. Do i need to replace the MAF or can i run it without? Will it hurt anything else w/o it? I even put in 87 octane and it ran fine with no "pinging"!!! I want to thank you guys for your help. I hope you all have a safe and happy holiday season!!
Mr.Mike1960
 

smokey

Hitech hillbilly
Staff member
Replace it. it provides input that meters the air fuel mixture. Without the MAF you will get poor fuel mileage and lose performance. Without the MAF unplugged the computer is running in Limp mode.
 

Skandocious

Post Whores Make Me Sick
19,076
655
California
Replace it. it provides input that meters the air fuel mixture. Without the MAF you will get poor fuel mileage and lose performance. Without the MAF unplugged the computer is running in Limp mode.
If the computer runs in limp without the MAF plugged in, then it might not be the MAF that's creating the problem... Running in limp would mean that it's disabling other sensors too; maybe one of those other disabled sensors is the problem.

If the MAF was giving out-of-valid-range readings then the computer should be able to pick up on it during the KOER test (one would think).
 

CowboyBilly9Mile

Charter Member
7,118
442
USA
Smokey is correct in that it provides data used to determine the correct A/F mixture, and you do need it. Exactly what ills will surface, above and beyond the MIL and probably not passing emissions, I don't know. I also can not concur that pulling the plug on the MAF proves it's a failed part and I would not yet replace it until a methodical diagnosis is performed. Later today, I will look for an alldata CD that should contain the information needed to do this. These CD's contain information from the manufacturer regarding how to service this vehicle; such data is also used by the shop at the dealerships. In this case, I will see if the CD provides a nice, convenient flowchart to help diagnose the problem in a orderly, systematic, and professional fashion. I will also see if I can locate the pinpoint diagnostic procedure for the MAF on this CD.

I would suggest plugging the MAF back in, clearing all codes, then go for a drive (or a few). Now pull codes and post all of them here. Make sure you note which they are, KOEO, KOER, or CM. To fix the problem correctly, you need to fix the codes in that order and withing each class (KOER for example) you need to fix them in a numerically ascending order. Failure to do this will produce unpredictable results as well as probably increase frustration and increase the chance of buying parts that didn't need to be replaced. People often think that codes and problems are always fixed by just "replacing a sensor". Sometimes that works, and sometimes not. Sometimes fixing one of the codes, a lower numbered code for example, clears another higher number code, one that may cause a person to think a sensor is bad. Fix that higher numbered code first and you may have just wasted time and money. See why it would be nice to get your hands on a flowchart and any needed pinpoint diagnostic proceedures?
 

Skandocious

Post Whores Make Me Sick
19,076
655
California
I can't seem to find any mention of which engine you're working on-- but Bill mentioned the 4.0 a couple times and we're in the V6 section, so I'm going to assume that's what we're working with. Here's the procedure for testing a MAF sensor on a 95 Ranger with a 4.0.






picture1dc6.png
 

Bob Ayers

North Carolina Chapter member
1,474
111
Durham, NC
Mike, you might try cleaning your MAF sensor. If the element is dirty, it will measure less airflow than is actually flowing, causing a lean condition, which results in "pinging".

A dirty MAF sensor will also cause the PCM to throw "LEAN" codes, which you are getting.


Bill has mentioned this same thing in his previous post.


One question, have you been running a K&N airfilter? If so, they are known to contaminate the MAF sensor, causing the problem you have described, as well as gumming up your
throttle body, and IAC valve.
 
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