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Discussion Starter #1
1) System Adaptive fuel too lean, bank 1
2) System Adaptibe fuel too lean, bank 2


Dont have a clue what that means, but thats what the book says.
 

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Discussion Starter #2
Hope that helps.
 

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sounds like a vacuum leak... check LT fuel trims...

is it stalling at idle? if your fuel trims are way positive at idle you've got a vacuum leak which will load the car up causing it to stall occasionally.

also could be pcv valve, but its probably a vacuum leak.
 

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Hope this helps, I had these codes and it ended up being my C&L MAF that was causing it so I put the factory one back one and the codes went away.

Codes P0171 and P0174 are your two FRONT O2 sensors. Your front O2 sensors are showing an overly rich signal. My
guess is either you have exhaust leaks between the exhaust manifold and your
pipe you installed, or you have an EGR valve stuck open.

Below is Ford's official troubleshooting to the issue.

Diagnostic Trouble Codes (DTCs) P0171 bank (1) (cylinder #1) and DTC P0174
bank (2) indicate the fuel/air ratio is too lean. The fuel adaptive system
is at the rich correction limit.

DTC P0172 bank (1) and DTC P0175 bank (2) indicate the fuel/air ratio is too
rich. The fuel adaptive syste is at the lean correction limit.

DTCs HO2S Reference list:

-- HO2S-11 = DTCs P0171 and P0172 Bank 1 (Pass side) Sensor 1 (Front)

-- HO2S-21 = DTCs P0174 and P0175 Bank 2 (Drivers side) Sensor 1 (Front)

Possible causes:

Fuel system

-- Excessive fuel pressure.
-- Leaking fuel injector(s).
-- Leaking fuel pressure regulator.
-- Low fuel pressure.
-- Contaminated injector(s)

Induction system

-- Air leaks after the MAF.
-- Vacuum leaks.
-- Restricted air inlet.
-- PCV system.
-- Fuel purge system.
-- Improperly seated dip stick.

EGR

-- leaking gasket.
-- Stuck open EGR valve.
-- Leaking diaphragm.

Base engine

-- Oil overfill.
-- Cam timing.
-- Cylinder compression.
-- Exhaust leaks before or near the HO2S's.

l Check air intake for leaks, obstructions and damage.
l Check air filter, air filter housing for blockage.
l Verify integrity of the PCV system.
l Check for vacuum leaks.
 

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I put the factory air box on with the factory MAF. I had the densecharger TB pipe w/ the C&L MAF on before that when it was idling wierd and throwing the codes. So I guess it could of been the Densecharger TB pipe and/or the C&L.
 

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My C&L made me run leaner on the A/F also. If you are tripping codes you need to me careful, A lean A/F will cause detonation.

I have heard of people with C&L and Densecharger setup having these problems, do a search on here.
 

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Sorry for the lack of info on what I did. I had problems submitting this. I reposted this ? further down the list.

But anyway. I checked for vacuum leaks. Tightened the EGR a little, cleaned the wires to my MAF ([email protected]), new PCV valve, new IAC. Last summer I had a EGR problem. I fixed it but not right away. I'm thinking it could be bad O2's?

It does want to stall at start up. Also I have air going thru the IAC tube at idle. I know its running rich, it just puzzles me cause I just got it out of storage 2 weeks ago. I didn't have this problem when I put it in storage. The only thing I did this winter was some new Iriduim plugs.
 

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Your not running rich. Your running lean. That is what the 0174 code means. Take off the C&L, then reset the Computer and I bet the codes will go away.
 

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I had those exact same codes not long ago.

Changing the fuel filter wouldn't hurt since it is so cheap to do.

If you have had a C&L MAF well before the codes came up, it is most likely not the problem.

I checked vacuum leaks and also lack of fuel delivery, but I eventually tracked it down to bad front O2 sensors. After replacing them with new ones, one drive later and the check engine light turned off.
 

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I have a 99 mustang v6 with the p1074 too lean bank 2 code, and I’m not quite sure what to do, because there are so many possible problems.
 
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