please help - nobody knows whats wrong with my car

[grcuadros]

i've had a CEL on for a while with the code p0171 - bank 1 lean. it first came on when i installed the SS afc and a 2.5" midpipe with a high flow cat about 2 years ago. since it came on 20 miles after driving i assumed the guy who installed the midpipe forgot to hookup the o2 sensor because the car drove fine.

well, i took the car to get fixed so i could pass emissions and so far the o2 sensor has been replaced, the MAF sensor was replaced, 2 bolts on the exhaust manifold were broken and have been replaced, every hose has been checked for a leak, and a mechanic friend has checked everything else possible but not had any luck.

then i took it to the dealership and they can't figure out whats wrong with it either. according to the service guy someone spliced into the harness and he won't mess with that.

so, i'm stuck with a car that won't pass emissions and still has a CEL on. any ideas??

the mods i have are:

injen cai
ss afc
manual boost controller
greddy turbo timer
2.5" mental addiction midpipe w/ high flow cat
fmic
short shifter

 

[yudkib]

what is with everyone getting p0171 these days. theres three threads on this very code in this section.

youre off to a good start, ill let you know if i think of anything

 

[PAracer]

Okay. Here's my two cents...

My first thought is that a wire has been pinched or shorted in the O2 sensor harness.
Take a look along it's path for signs of melting, chaffing, or anything that might have been crushed.

Please note that I have only had a MSP for 4 days. My knowledge base is in general car stuff.

 

[njaremka]

i've had a CEL on for a while with the code p0171 - bank 1 lean. it first came on when i installed the SS afc and a 2.5" midpipe with a high flow cat about 2 years ago. ...

perhaps the SSAFC is causing the issue? just a guess...

 

[Wagonbacker9]

perhaps the SSAFC is causing the issue? just a guess...

doubtful

My bet is that its the high flow cat. swap the stock midpipe back in and see what happens. I'll bet you the code drops.

If it stays, then its your wiring on the secondary O2 thats bad. I believe you have to extend the harness to get the 02 to the plug on the catted midpipe. I have the MAM catless and it BARELY reached.

 

[njaremka]

doubtful

My bet is that its the high flow cat. swap the stock midpipe back in and see what happens. I'll bet you the code drops.

If it stays, then its your wiring on the secondary O2 thats bad. I believe you have to extend the harness to get the 02 to the plug on the catted midpipe. I have the MAM catless and it BARELY reached.

now, why would you say "doubtful"? the lean code is going to come from the front o2 sensor, which doesnt care what's downstream from it. NONE of the triggers for P0171 are for anything downstream from the first o2 sensor.

Possible causes for P0171 from shop manual:

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Misfire​

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HO2S (front) deterioration​

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HO2S (front) heater malfunction​

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PRC solenoid valve malfunction​

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Pressure regulator malfunction​

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Fuel pump malfunction​

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Fuel filter clogged or restricted​

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Fuel leakage on fuel line from fuel delivery pipe and fuel pump​

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Fuel return hose clogged​

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Leakage from exhaust system​

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Purge solenoid valve malfunction​

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Purge solenoid hoses improper connection​

Insufficient compression

 

[Wagonbacker9]

I say its not the SSAFC because the SSAFC clamps the 02 signal when it is active (prevents the ECU from learning around the tune on the AFC), so the code is being generated when the SSAFC is inactive. Seeing as the primary has been replaced, I'm looking at either wiring, or the secondary getting a reading which is at a differential which does not fit the window from the primary that it is expecting to see.

But, thanks to your input, and it forcing me to think a little harder, I'd also like to add to consideration the SSAFC wiring where it was tapped into the ECU, because you cut into one of the primary O2 wires in order to wire in the AFC.

 

[njaremka]

I say its not the SSAFC because the SSAFC clamps the 02 signal when it is active (prevents the ECU from learning around the tune on the AFC), so the code is being generated when the SSAFC is inactive. Seeing as the primary has been replaced, I'm looking at either wiring, or the secondary getting a reading which is at a differential which does not fit the window from the primary that it is expecting to see.

But, thanks to your input, and it forcing me to think a little harder, I'd also like to add to consideration the SSAFC wiring where it was tapped into the ECU, because you cut into one of the primary O2 wires in order to wire in the AFC.

knowing what it does makes me think ever more that the SSAFC was installed incorrectly. if its causing the ecu to not see the correct voltage from the o2 sensor, the stock ecu will throw a code.

 

[Wagonbacker9]

I would tend to agree, however the SSAFC shows the ECU correct O2 voltage whenever its active (assuming proper wiring), so the wiring to the 2nd O2 is still suspect in my eyes too. I do wanna lean toward this being a wiring problem one way or the other though.

 

[Carlinator]

Did you check your air filter? My shop had a 3 in yesterday that had the same code, turned out to be oil from their K&N filter leaking onto the maf sensor, causing it to read less air than there actually was, injecting less fuel and making it run lean. If you've got one of those, or just a stock one you haven't changed in a while, you might want to clean or replace it as applicable.

 

[Wagonbacker9]

Did you check your air filter? My shop had a 3 in yesterday that had the same code, turned out to be oil from their K&N filter leaking onto the maf sensor, causing it to read less air than there actually was, injecting less fuel and making it run lean. If you've got one of those, or just a stock one you haven't changed in a while, you might want to clean or replace it as applicable.

he went one better and replaced the whole MAF sensor.

 

[808MP5]

subbing to see the solution...
i would also guess maybe bad wiring of the ssafc... you could always try to take it out and see what happens... well easier said than done if you soldered your connections... scissors

 

[Wagonbacker9]

why doesn't anyone seem to know that you in fact CAN reheat the solder and seperate the wires?its like its a one way plane ticket. You can always buy another one... "One way" isn't permanent.

 

[808MP5]

why doesn't anyone seem to know that you in fact CAN reheat the solder and seperate the wires?its like its a one way plane ticket. You can always buy another one... "One way" isn't permanent.

hehe... i wasn't thinking lol

 

[Wagonbacker9]

Didn't mean to direct that at you, you just reminded me of it. I've seen people refuse to buy the SSAFC because of its "Install and uninstall difficulty" and idk... I guess I just think its nuts on both counts.

 

[ohdavy1]

Could be an exhaust leak? Did you replace your gaskets when you installed the new midpipe?

 

[Bluemica3.5]

when i had this code pop up last summer. i bought a new front o2 senser since mine looked like it imploded. code went away and still hasent came back.

 

[MSP2003.5_Nick]

Since you have a high flow cat have you looked into the o2 sensor wiring trick? It's in the how to section and explains how to add a resistor and capacitor to trick your ecu into thinking the signal is good. I'd try that for sure

 

[Wagonbacker9]

usually you don't need those for a high flow cat... but I suppose depending on how effective the cat is(n't) you still may

 

[Speed3.5]

I'd suggest disconnecting(take off SSAFC) and see if CEL goes away , I had same CEL coming and going when I had Emanage BLUE/GOLD installed which required clamping O2 sensor and that somehow triggered CEL , I'm sure this is the likely hood in your case as well. I didn't replace any of the parts you did but since I build O2 clamp myself I mingled with it to avoid CEL which helped only for few weeks then it would return. Ever since I took it off that CEL never came back.
Don't forget that MAF signal is clamped too so if you want to make sure its not the SSAFC then disconnect it and make sure everything is in stock condition (wiring wise) and give it few days if it appears again then it might have to do with something else(which I doubt)