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Discussion Starter #1
P0175 and P0171

Hey guys,

I̶'̶v̶e̶ ̶b̶e̶e̶n̶ ̶t̶r̶y̶i̶n̶g̶ ̶t̶o̶ ̶d̶i̶a̶g̶n̶o̶s̶e̶ ̶t̶h̶i̶s̶ ̶a̶l̶l̶ ̶d̶a̶y̶ ̶u̶s̶i̶n̶g̶ ̶t̶h̶e̶ ̶F̶o̶r̶d̶ ̶w̶i̶r̶i̶n̶g̶ ̶d̶i̶a̶g̶r̶a̶m̶s̶ ̶(̶o̶w̶n̶ ̶t̶h̶e̶ ̶b̶o̶o̶k̶)̶ ̶b̶u̶t̶ ̶c̶o̶u̶l̶d̶ ̶u̶s̶e̶ ̶s̶o̶m̶e̶ ̶h̶e̶l̶p̶.̶ ̶l̶o̶o̶k̶i̶n̶g̶ ̶a̶t̶ ̶t̶h̶e̶ ̶O̶2̶ ̶p̶i̶g̶t̶a̶i̶l̶ ̶(̶f̶r̶o̶m̶ ̶t̶h̶e̶ ̶t̶r̶a̶n̶s̶ ̶h̶a̶r̶n̶e̶s̶s̶)̶ ̶I̶ ̶f̶o̶u̶n̶d̶ ̶t̶h̶a̶t̶ ̶t̶h̶e̶ ̶h̶e̶a̶t̶e̶r̶ ̶s̶i̶g̶n̶a̶l̶ ̶(̶y̶w̶/̶l̶b̶ ̶t̶o̶p̶ ̶l̶e̶f̶t̶ ̶i̶n̶ ̶t̶h̶e̶ ̶i̶m̶a̶g̶e̶)̶ ̶i̶s̶ ̶b̶e̶i̶n̶g̶ ̶p̶r̶o̶v̶i̶d̶e̶d̶ ̶1̶2̶v̶ ̶f̶r̶o̶m̶ ̶t̶h̶e̶ ̶E̶C̶U̶ ̶(̶c̶h̶e̶c̶k̶e̶d̶ ̶a̶t̶ ̶t̶h̶e̶ ̶s̶e̶n̶s̶o̶r̶ ̶w̶i̶t̶h̶ ̶t̶h̶e̶ ̶t̶r̶a̶n̶s̶ ̶h̶a̶r̶n̶e̶s̶s̶ ̶c̶o̶n̶n̶e̶c̶t̶e̶d̶ ̶a̶n̶d̶ ̶a̶t̶ ̶t̶h̶e̶ ̶E̶C̶U̶ ̶w̶i̶t̶h̶ ̶t̶h̶e̶ ̶t̶r̶a̶n̶s̶ ̶h̶a̶r̶n̶e̶s̶s̶ ̶d̶i̶s̶c̶o̶n̶n̶e̶c̶t̶e̶d̶)̶.̶.̶i̶s̶ ̶t̶h̶i̶s̶ ̶n̶o̶r̶m̶a̶l̶?̶ ̶I̶'̶m̶ ̶n̶o̶t̶ ̶a̶b̶l̶e̶ ̶t̶o̶ ̶r̶e̶p̶l̶i̶c̶a̶t̶e̶ ̶t̶h̶i̶s̶ ̶b̶e̶h̶a̶v̶i̶o̶r̶ ̶o̶n̶ ̶t̶h̶e̶ ̶p̶a̶s̶s̶e̶n̶g̶e̶r̶ ̶s̶i̶d̶e̶.̶ ̶T̶h̶e̶ ̶t̶o̶p̶ ̶r̶i̶g̶h̶t̶ ̶p̶i̶n̶ ̶i̶s̶ ̶b̶e̶i̶n̶g̶ ̶p̶r̶o̶v̶i̶d̶e̶d̶ ̶w̶i̶t̶h̶ ̶1̶2̶v̶,̶ ̶a̶s̶ ̶i̶s̶ ̶t̶h̶e̶ ̶p̶a̶s̶s̶e̶n̶g̶e̶r̶ ̶s̶i̶d̶e̶.̶ ̶I̶ ̶r̶e̶p̶l̶a̶c̶e̶d̶ ̶t̶h̶e̶ ̶f̶r̶o̶n̶t̶ ̶d̶r̶i̶v̶e̶r̶ ̶s̶i̶d̶e̶ ̶O̶2̶ ̶s̶e̶n̶s̶o̶r̶ ̶t̶h̶i̶s̶ ̶m̶o̶r̶n̶i̶n̶g̶ ̶w̶i̶t̶h̶ ̶a̶ ̶b̶r̶a̶n̶d̶ ̶n̶e̶w̶ ̶B̶o̶s̶c̶h̶ ̶s̶e̶n̶s̶o̶r̶ ̶b̶u̶t̶ ̶a̶m̶ ̶r̶u̶n̶n̶i̶n̶g̶ ̶i̶n̶t̶o̶ ̶t̶h̶e̶ ̶s̶a̶m̶e̶ ̶i̶s̶s̶u̶e̶ ̶s̶t̶i̶l̶l̶ ̶(̶I̶ ̶f̶o̶u̶n̶d̶ ̶o̶u̶t̶ ̶a̶b̶o̶u̶t̶ ̶t̶h̶e̶ ̶v̶o̶l̶t̶a̶g̶e̶ ̶a̶f̶t̶e̶r̶ ̶r̶e̶p̶l̶a̶c̶i̶n̶g̶ ̶t̶h̶e̶ ̶s̶e̶n̶s̶o̶r̶.̶.̶ ̶ ̶ ̶(̶I̶ ̶g̶o̶t̶ ̶t̶h̶e̶ ̶i̶n̶f̶o̶ ̶f̶r̶o̶m̶ ̶t̶h̶i̶s̶ ̶t̶h̶r̶e̶a̶d̶:̶ ̶h̶t̶t̶p̶s̶:̶/̶/̶f̶o̶r̶u̶m̶s̶.̶c̶o̶r̶r̶a̶l̶.̶n̶e̶t̶/̶f̶o̶r̶u̶m̶s̶/̶e̶l̶e̶c̶t̶r̶i̶c̶a̶l̶-̶w̶i̶r̶i̶n̶g̶/̶2̶2̶0̶4̶1̶8̶6̶-̶o̶x̶y̶g̶e̶n̶-̶s̶e̶n̶s̶o̶r̶-̶e̶n̶g̶i̶n̶e̶-̶h̶a̶r̶n̶e̶s̶s̶-̶h̶e̶l̶p̶.̶h̶t̶m̶l̶)̶

Update: I fixed the initial wiring issue but not I'm running into P0171 and P0175 codes. Things I have done so far: Checked for exhaust leaks, pressurized and smoked the intake (no more leaks), replaced the driver O2 sensor (both driver and passenger were new and had ~50 miles on each), validated the O2 wiring is correct. My next thoughts are that the MAF may need to be cleaned and that the tune may be bad (bama threw me an unrevised tune for a very, very modified engine). I never ran into any of these issues until I swapped to fully ported upper and lower intakes and a larger throttle body.
 

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Discussion Starter #3
Okay, so I have a new update...I checked the wiring and re-seated the connectors and that seems to have fixed the p1151. Now I'm getting a P0171 (System too lean - bank 1) and a P0175 (System too rich - bank 2).

I know there are no intake leaks as yesterday I literally pressurized and smoked the intake and fixed 6 vacuum leaks. I have also thoroughly inspected the exhaust and can find no leaks or residual marks from a leak.

I just had Bama throw on a tune (the vehicle is HEAVILY modified), do you think it could be tune related?
 

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Discussion Starter #5
Normally I would say yes, but the passenger front O2 is not part of the transmission harness. The only thing I can think of when it comes to messing with the wiring would be if it was wored incorrectly but I verified each and every pin on both harnesses before I swapped the connectors and on the ECU after I swapped them.
 

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Discussion Starter #7
Unplug either the driver or passenger O2 sensor and test the signal at the ecu, which I inadvertently did. When I went to test the drivers side initially I couldn't see any signal at the ecu until I plugged it back in (I've been using the Ford wiring diagram book for my model and year mustang).
 

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Discussion Starter #9
Yes, the voltage being received by the ECU should be 0. Once I plugged the sensor in (with the ignition on and the car not running) I was getting around 200mv.
I updated the original post with some more info
 

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so the signal did NOT change from the 02?

you unplugged it, of course the ecu will see nothing, but what about the signal?

the easiest thing to was to take the bank that is reporting rich, cut the signal, then watch the short term fuel trims. or erase the codes, drive and recheck
 

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Discussion Starter #11
I don't mind retesting it, but to clarify, start the car, view fuel trims, unplug the rich bank, see what changes for the short term fuel trims?
 

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Discussion Starter #12
Alright, I just stopped by the house and tested how I described: First I cleared the codes, started data logging with my SCT, started the car, noted the short term fuel trim was around 93-95, unplugged the bank 2 (drivers side) front 02 sensor, noted the short term fuel trim was now reading a flat 75.

Edit: I'll add that the passenger fuel trim was just about mirroring exactly what the drivers side was until I unplugged the drivers side front o2 sensor.
 

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ugg

i didn't want the trims cleared

I wanted you to see if the trims correct

If the 02 is fixed rich, as your code states, if the 02 signal goes to 0volts, that bank should start adding fuel.............do you follow?
 

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Discussion Starter #14
I see where you're going with this. I'll let the car idle again today to get the trims to even out. My only concern is something I read on another thread while researching this (I can't find it for the life of me). If I disconnect the 02 sensor, the car notices the 02 is disconnected and defaults to the static fuel table (or whatever it's called). The only thing i can think of doing is cutting just the signal wire while the car is running or cutting the wire and inserting my own voltage.

One thing I did do yesterday when I drove the car and got the codes is give it ~75% throttle from a stop, which still makes me think it could be a tune issue.. I am very open to ideas though, I just want to get this fixed.
 

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cut the wire on the 02 side, do not insert a voltage

You do it on the side that is reporting rich, that 02 should reporting near 1 volt

Once the ecm sees low, it will add fuel
 

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Discussion Starter #16
Sorry for the late replies, school and work got VERY busy. The fuel trim isn't fixed rich, it fluctuates but it is always MUCH higher than bank 2. I can post some datalogs if that'll be helpful to see, just let me know
What I did do in the meantime is I swapped exhaust gaskets and found that two of the bolts on the bank 1 side were stripped, causing an exhaust leak. I swapped that gasket, drilled and tapped the holes and noticed the car ran more lean on bank 1 than it was before...wtf?? I decided to swap the gaskets AGAIN but it's still behaving the same way.
I did notice that when the car is idling, bank 1 short term fuel trim runs very rich in comparison to bank 2. However, when i step on the accelerator and hold any RPM the short term fuel trim on both banks are extremely close together, as it should normally be. Any ideas?
My next thoughts are to test the fuel injectors, clean the maf, maybe perform another test for a vacuum leak even though I just made sure the intake side is solid. Exhaust side, everything seems to be in proper place with no more leaks but I can't be 100% sure.
 

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Discussion Starter #17
Got an update from the tuner:

"Looking over this data log I am seeing the fuel trims showing opposite from each other when the car is at idle (one bank rich and one bank lean). You are right though that the fuel trims clean up when the engine is under load. This could be the result of the cams being out of time and showing this type of issue when at idle as that is when the duration would be most prevalent and clearing up with the RPM's since the cams are turning faster and this would clear up then.

Without having the vehicle present this is hard to determine just from a data log though. For something like the cams being out of time I would have a performance shop inspect the car before pulling things apart."

This coincides with the work that was just done on the engine before the issue popped up (a shop replaced the timing chain and tensioner). Could the cam actually be out of sync with the crank? The 3.8 v6's are interference engines.
Another thought, could this have something to do with the camshaft synchronizer? I have no idea how to test or adjust it.
 

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Discussion Starter #19

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Sorry for the late replies, school and work got VERY busy. The fuel trim isn't fixed rich, it fluctuates but it is always MUCH higher than bank 2. I can post some datalogs if that'll be helpful to see, just let me know
What I did do in the meantime is I swapped exhaust gaskets and found that two of the bolts on the bank 1 side were stripped, causing an exhaust leak. I swapped that gasket, drilled and tapped the holes and noticed the car ran more lean on bank 1 than it was before...wtf?? I decided to swap the gaskets AGAIN but it's still behaving the same way.
I did notice that when the car is idling, bank 1 short term fuel trim runs very rich in comparison to bank 2. However, when i step on the accelerator and hold any RPM the short term fuel trim on both banks are extremely close together, as it should normally be. Any ideas?
My next thoughts are to test the fuel injectors, clean the maf, maybe perform another test for a vacuum leak even though I just made sure the intake side is solid. Exhaust side, everything seems to be in proper place with no more leaks but I can't be 100% sure.
answer my previous post
 
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