P0171, P0174 and P0113 help!

I need your guys help…My 2005 mustang gt has a p0171 and p0174 code as well as p0113 (for the IAT sensor).

For starters, the wiring to the MAF connector or the connector itself isn’t visibly damaged.

I already replaced the MAF sensor which has the IAT sensor built into it on my car and cleared the codes with a scanner. Then disconnected the battery for 10 minutes to reset the ecu but the engine still runs the same as before replacement and clearing the codes…it runs rough when idling, especially when first starting the car with the engine already at operating temp. Rpms fluctuate and car shakes a little/feels rough. Once it gets moving the roughness is mostly gone.

Cold starts don’t seem to have an issue.

Does the new MAF sensor need to go through several drive cycles to start working properly or could there be another issue? I know P0171 and P0174 generic lean codes could have so many possibilities but the fact that it throws P0113 as well points to really only the MAF sensor.

Any help is appreciated

Ford Mustang: P0171 and P0174 Diagnosis | Drivetrain Resource (700r4transmissionhq.com)

Normally if diagnosing a general lean condition with no other codes I would try to go down the list of those possibilities and eliminate one at a time…

but the fact it threw a more specific code (p0113) and I addressed it and the problem still exists is puzzling.

The check engine light hasn’t come back but the car is still running the same as before

check the wiring going to the AIT

I visually inspected it and there’s no physical damage from what I can tell. I will probably use a multimeter tomorrow to check the voltage.

Is there some procedure that must be done after replacing the MAF sensor so it “learns” or performs correctly? I just cleared the codes and then disconnected the battery for 10 minutes after replacing but no help

When you check the wiring, inspect the contacts in the connectors for oxidation. This can be an issue on a 17 year old car. I’ve had that problem in the past.

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The 3 codes you got, 174, 171 and 113 ALL point to a bad MAF… which you replaced. Two bad MAFS would seem a bit too coincidental. Bad wiring would be my guess given the codes and MAF replacement.

If your code reader allows you to read the long term fuel trims (LTFT), MAF and the IAT reading while the car is running. do that. The IAT reading should be pretty close to the outside air temp while you are driving plus about 2 to 4 degrees. Read the MAF reading as well to see if it is steady at idle and at highway speeds with the cruise control on. Basically you are looking for readings that make sense and don’t drop to zero or go infinite.

The LTFT1 and 2 should be close to zero all the time, or at least less than +/-20%. If they run high or low at idle and then drop at speed, that is significant. Same if they are OK at idle and go high or low at speed.

Post what you find and we can go from there.

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