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Discussion Starter · #1 ·
Okay, my CEL (Check Engine Light) has been coming on quite often lately, so I decided to scan the Engine Codes. Well, I came up with two error codes, 172 and 186.

I already know what they mean, and here are the definitions:

172 - Oxygen sensor not switching. system is or was lean. Single, Right or Rear HO2S.

186 - Injector pulse width longer than expected or Mass Air Flow (MAF) lower than expected.


What I need to know is, does this mean I should replace my O2 sensor? Also, which do you think would be causing EC 186? Fuel Injector or MAF Sensor?

If the problem is in the injector, what do I need to do to further diagnose the problem? (i.e. - which injector, if any, and if none at all)

Any help whatsoever would be greatly appreciated.
 

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Those are good ones. Im not a mechanic, so dont take my word for anything. These are only suggestions to help you go a little further.
Is it a MAF on the lx or the VAF like the GT??? Have you made any adjustments to it at all?
If you do some research, you can replace the O2 sensor pretty cheaply. Otherwise, check the spark-plug condition. Maybe one of them has some tell-tale signs that will help you decide if one of the injectors are bad or dirty. check the condition of the spark plug wires. The metal terminals under the rubber boots get corroded sometimes....kind of a blue-green corrosion.
Im not too sure about how to check the VAF or MAF or whatever you have. Id assume its a series of resistance or voltage measurements under varying conditions. Let us know if you find anything more. Good luck!
 

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Discussion Starter · #4 ·
Well I think what I'm going to do is drive around until the CEL comes back on and see what comes up after that. One of those codes may be in there from a while ago, so I cleared them out to check later.
 

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FourDiceS04 said:
I'd say the oxygen sensor is lean because the injectors width is longuer than expected...
lmao. hmmm...I dunno, what brought you to that conclusion :p

There's a possibility that it's probably a problem with the fuel delivery... hehe

I dunno I know you don't have time to tear it apart but the fuel pump might be dying or it just could be a single injector that's done for. :?
 

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Discussion Starter · #7 ·
Well, I've decided that tomorrow morning, I'm going to check all of the injectors to the best of my ability and see if any of them are malfunctioning.

If they turn out to be okay, I am going to check the fuel pump. What would be the best way to do this, do a fuel pressure test I'm guessing?
 

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I was just thinking about it a little more, we (phone guys) sometimes use voltmeters to check the voltage coming across on telephone pairs to check for shorts... if you have a volt meter you could try to hook it up to the injectors and see what kind of impedance/resistance/voltage they read. Chances are if one is different than the other three that's your problem. If not it could be a fuel pump related issue... (assuming of course this is fuel related in the first place)
 

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Discussion Starter · #9 ·
Actually, I JUST saw something online that says to disconnect the wiring from each injector while the engine is running and see if the engine speed changes (one at a time, i.e. - start car, pull injector wire #1, put back on, pull #2... you get the idea). Apparently, if the injector is good, then the engine RPM's will drop when you disconnect the wire, but if the injector is bad, then the RPM's will stay the same. I don't know, makes sense to me anyway, but what do I know.
 

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That sounds right. if you pull it and the engine slows then that injector is still good. if you pull it and it stays the same, then that injector wasn't spraying anymore. :wink:

Good luck, I hope it's just something really simple.
 

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Discussion Starter · #11 ·
Believe me, so do I. I think while I'm at it, I'm gonna check my plugs and do a compression check. Might as well anyway. If the problem is something simple, I may even replace my plug wires, since they look quite old and could probably use to be replaced anyway.
 

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good in theory, as long as the injector is messing up at idle as well as when it's pumping alot of fuel. :)

the only part that gets me is - the injector is pulsing too long but you're running lean? That's all sorts of backwards.. but i'm no electronics man..
 

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Discussion Starter · #13 ·
Yeah, that's the thing that's throwing me off. Unless the injector is clogged, so it's not putting out as much fuel as it should, and the clog is causing the injector to stay open too long. I could be completely wrong though, as I'm not completely sure exactly how the injectors work. (I know how they work and what they do, but I don't know the actual parts of the injector and what not.)

Wow, injector doesn't even seem like a word any more!

Roads, roooaaads, rowwww-ads, rowads... hehehe.
 

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The way I understand the 1.9 SEFi to work, is there is 1 injector per cylinder. Sequential Electronic fuel injection means that it injects the fuel exactly with the firing order (duh).

What I'm clueing myself into (finally) is that the injector had that trouble code saying it's staying open too long, yet the O2 says it's running lean. I bet one injector is clogged and it's staying open longer to try to make up for the loss.

[/babble] :lol:
 

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has the engine bay gotten really wet lately? or did you wash the engine lately? Water may have leaked into a spark plug or into an injector hole causing the 172 code.
 

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Discussion Starter · #17 ·
No, no water has gotten into anything. I was just under the hood installing a home-made ground wire kit and I didn't see anything out of the ordinary. And just so you know, the CEL was coming on before I installed the ground wires, so they don't have anything to do with it.
 

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Discussion Starter · #18 ·
Well, I just got done checking the injectors and what not. The all seemed to work fine, at idle anyway. I also looked at my spark plugs and did a compression check, the spark plugs showed a little wear, but the compression check turned out wonderfully.

I have no idea what else could be wrong.

Oh, and I also checked the engine codes again, if only to clear any out that came up while I was checking the injectors, and I got the "Keep Alive Memory Test Failed" again. If anyone else could help me out with this problem, I would be greatly appreciative. I'm about to just call a dealership and see what they say it could be.
 

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Discussion Starter · #19 ·
Well, I just talked to a Ford mechanic, and he said that the possible causes for 172 and 186 are the MAF or a vaccum hose leak. The 512 (KAM test failure) is caused by a loss of power to the ECU, whether it be a relay or a loose ground or something. So hopefully my problems consist of a vaccum hose leak, and a easy to locate loose ground or something.
 

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Discussion Starter · #20 ·
Well, I just got back from raquetball and th eonly code to come back was 186 (Injector thingy). Just thought I'd mention this.
 
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