So last week the check engine light came on. I took it to the dealer and they fixed it. Codes were PO172 and P0175. Too rich in both banks. According to the sheet they gave me, they replaced the airflow sensor.

Well, a week later I get the code again. This time I checked it with a SCT just to get the codes. Same codes. Also, my fuel pressure is around 25psi. Usually its around 39-41 because I have upgraded the fuel injectors. Anyone know what can be causing this?

Any help would be greatly appreciated!

 

You have upgraded the fuel injectors, did you have the computer reflashed when you did this? If not, that may be a reason for the banks running rich.

 

Yes, the computer was reflashed after the install of the injectors and s/c. That is one of the reasons that I am wondering why its happening.

 

try sct or maybe one of the tuner guys here like CR from tillmanspeed or Doug from Bamatunes can help you out.

 

Hate to revive this old thread, but has anyone found out what causes this? Is it the airflow meter? My 2005 is doing the same thing, and I cleared them out tonight. Just wondering if anyone had any solutions.

 

Just an FYI for you folks having these PO172 and PO175 codes. Tried an airflow meter tonight, and it did NOT fix the issue. Car doesn't seem to run right either; seems to be down on power. I'm starting to wonder if it might be the fuel pressure sensor on the rail. I can't smell gas, and there's no smoke like excess fuel, so I'm having a hard time thinking it's really dumping fuel. Just hope it's not the fuel pump. I guess I'll have my techs at my dealership check it in the morning when I go to work.

 

if youve had the battery out(maybe after a reflash too?), part of calibration requires engine braking from 60 mph to under 40 to calibrate the misfire sensor. mine was wacked last week bigtime- had changed battery, drove a couple days(not highway) then short highway trip over 60, decelled a little and pushed the clutch...after it would barely even run. doubt its causing yours, but might be worth a try to unhook the batt, warm it up and take it over 60 in third then coast down to 40 in gear/engine braking. mines like new again...

 

Ford4v429 I have a 05 GT and just had a new battery put in and now the idle is rough and sometimes it even dies. Would this missfire calibration you are talking about be something worth trying? If so, tell me step by step how to do so.

 

I wish Id saved the document...anyway it just said the way it calibrates is a engine braking decelleration from over 60 mph to under 40...mines a stick, I just unhooked the battery, touched the leads together for a few seconds to clear anything, let it warm up, took it on the road to over 60 in third, coasted down to under 40 a couple times and all the issues went away. the thing I read was a ford tech bulletin, it said the misfire calibration made up for machining errors in the fine toothed starwheel that a sensor reads to check how many milliseconds per degree type of thing to watch crankshaft acceleration pulsations from firing...the deal with coasting down is there is no firing pulses twisting the crank, so all signals are purely mechanical timing- or something like that...

mine was fine after swapping battery, but a little down on power as the driving cylces hadnt tuned everything yet, but the third day of driving was first time on the highway, and I hit the clutch on the offramp- think it just confused the calibration software to mapping bad data- but it was horrible, stalling, idling from like 400-2000... letting it 'relearn' seems to have fixed everything.

something else that seemed to help(but some knowledgable tuners said it has zero effect on Fords- sure made mine act different though)is the pedal calibration...just turn the key on but dont crank it (and no brake pedal), wait for airbag/couple other lights to go off, smoothly press pedal to floor/smoothly release, turn key off wait a few seconds before starting up. the purpose was supposedly to calibrate pedal input range to TB open/closed range, I swear it helped my balky pedal go back to normal, but some swear it could not have...who knows- but as it cant possibly hurt anything, worth a try

 

Thanks for the help. I will give it a try tomorrow. I hope it works!