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P0172 Please help!! Out of Ideas

Old 04-06-2019, 12:37 AM
  #1  
oceanman123
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Question P0172 Please help!! Out of Ideas

First time posting.... Now that I have been fighting with this issue for almost two months, I really need help with this thing. I will make it as detailed as possible as well.

So in mid February I started noticing drastic drops/unstable in RPM after cold starts (below 500) at idle. I cleaned the throttle body and check for any leak, but did nothing, only to make it actually worse. I got the cel soon after, and it turned out to be 2nd cylinder misfire. At this point I went ahead and replaced all six sparkplugs and injectors, followed by brand new wires, coil pack, and also air filter. The problem turned out to be caused by the busted wires and the old coil pack.

After all those replacement it threw a code P0175 (system too rich on bank 2). My mechanic recommended MAF sensor replacement, which I did right away. Didn't help. Slowly it had gotten worse with rough idle, hesitation, power loss----typical symptoms for the code.
Then I took it to mechanic for full diagnostics, and they found out that the fuel injector #3 (brand new) was defective. So I order another one, and replaced it with #3. Didn't help.
I brought it in again to see what's going on, and then they told me injector #4 was defective. Surprisingly, they actually put #3 back in place of #4 because when they tested #3 it seemed okay. Of course, it didn't help.
At that point, it was giving the new code, P0172 (system too rich on bank 1). the mechanics diagnosed it, and they told me that now injector #2 was spraying too much. I started to think that the whole set of the new injectors was basically bad, so I asked them to clean the original injectors (which I luckily kept them just in case) because injectors were not the root of the problem in the first place. They cleaned, even them out, and replaced them back all together with the supposedly defective set. They also put new o-rings on them as well.

After one week, the cel came back on with the same code P0172.
I really don't wanna go with this mechanic anymore because I feel like they never make sure that they fixed the "root" of this issue. I have been paying for labor each time when they take the intake out to get to the injectors, and I know for sure its getting ridiculous.
I am trying out the new mechanic for second opinion soon, but in the meantime I hope someone can give me some ideas. What else could it be???

Thank you very much!!!!!!
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Old 04-12-2019, 10:49 PM
  #2  
sidthesloth
 
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hey i dont know if this will help but in a nut shell i had an issue with my engine months ago. it would go from rich to lean rich to lean with the engine codes.
and i too replaced and or cleaned TPS, IAC, MAF and injectors.
i was having an idle issue and stalling issue (stick shift) all while going back and forth of having lean and rich codes.

if you're swaping injectors and the sawp had no affect then it tells you that that is the spot of issue. which means its NOT an injector or fuel issue because if your only have a bank issue and not a whole engine issue as in each individual code for rich for each cylinder. then you have a vacuum leak

sorry read you post fast so if i assumed and or read wrong i apologize
RPM issues being lower and fluctuate
hesitations TYPICALLY in the idle and very very low RPM off of idle.
almost always a vacuum leak

and to my example
i was trying out a 4.3 build and when i got the gasket that seals from the lower intake to the cylinder head i noticed the gasket wasnt "flush" with the ports so i widened them to match.
well i ever so slightly over ported one of the ports (couldnt tell it looked spot on and app it wasnt)
put the engine all together and soon after that my car was throwing codes left and right for lean and rich... i would change something it would switch to too lean.... replace something else and had it retuned and it would then be too rich.

check all your hoses on the engine listen for a sucking sound or better yet get a can of brake cleaner and start spraying contact spots for your hoses and if your RPM races real quick when you spray a spot.... you found your leak.
for me i sprayed the contact spot where the lower seals to the head in the back corner (because my tuner said that was the cylinder on that bank only running rich even though i got a generic bank code)(cly 6)

and when i sprayed it i heard a noticeable RPM increase every time i sprayed

cheak ALL the hoses make sure the rubber seals that go into the ventilation system on the top of your valve cover.... they are rubber and like to dry out and crack.

check all hoses and where they connect to the points on the engine and spray all gasket areas...upper to lower, lower to the head.

if your getting a bank code to one side and only one side its not going to be an issue BEFORE the throttle body, because if you did....it would be throwing both banks. meaning your throttle body, MAF and all the piping from the filter to the body is not the issue

sorry for spelling and grammar, i was just trying to out right explain how i had a similar issue with injectors and it was the gasket that failed at that injector or in this case the cylinder it self, not the injector
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Old 04-12-2019, 10:58 PM
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sidthesloth
 
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just to clarify your getting JUST a cylinder 2 rich code, not the generic bank 2 code?

and the first part of your post you said you took an injector from number 4? which is from the driver side to sawp with number 3 on the driver side? and it didnt change?
and you changed bank 's injectors all together? which would be cylinders 1 2 and 3 and now its a specific cylinder rich.....im willing to bet you have a failed gasket that leads to cly 2.


if its just a code for the cylinder?
i would say take some break cleaner or Aether and spray all contact spots for the cylinder ....see if it affects RPMS and do be afraid to really spray it.
also what i had happened originally had a complete total engine lean code (i have a windstar upper intake on mine) the o-rings that sat inbetween the intake and the bolts were hard and dry rotted so they didnt compress down properly to seal the intake gasket.... got new rings and that solved it untill i realized the big underlying problem was an over ported head that wasnt being sealed by the gasket.
that and make sure none of your bolts to the upper intake didnt loosen up specially the two bolts that are around cly number 2 (you'd be surprised )
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Old 04-13-2019, 12:03 AM
  #4  
oceanman123
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Thanks a lot for your thoughts.

I brought it to another mechanic today for the "second opinion." Turned out that the brand new MAF sensor (OEM) was failing. UGH.....
Luckily everything else seems fine: Injectors doing alright, no vacuum leaks, etc.

My journey almost comes to an end. It is just sad that parts I bought from online basically made it extremely complicated and stressful....
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Old 04-13-2019, 12:12 AM
  #5  
oceanman123
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Default fixed ?

Just as I mentioned, the last residue of the issue was from the MAF sensor I replaced. I will go ahead and put the old motor craft one back in

Experience learned:

1. Do not buy parts from online unless you are confident they are up to specs. (both injectors and MAF sensor were defective after all).
2. It is sometimes worth the cost having it diagnosed by the professionals.

Thanks.
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Old 04-13-2019, 01:16 PM
  #6  
sidthesloth
 
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Originally Posted by oceanman123 View Post
Just as I mentioned, the last residue of the issue was from the MAF sensor I replaced. I will go ahead and put the old motor craft one back in

Experience learned:

1. Do not buy parts from online unless you are confident they are up to specs. (both injectors and MAF sensor were defective after all).
2. It is sometimes worth the cost having it diagnosed by the professionals.

Thanks.
Yeah sorry for jumping to vacuum leak I assumed you checked o2 sensors ECT ...my bad and yeah that'll do it.... Burnt out o2 sensors won't give the engine the reading it needs to judge the exhaust gasses to adjust the ratio.... So yeah good find my bad
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