HC: Fuel Delivery System HC: Introduction — 2016 workshop reference 5139

Vehicle applicability: This diagnostic supplement covers multiple Ford vehicles and engines. Follow the application named in the source below. Some references apply to vehicles other than Mustang.

HC8 RESET THE PERCENT ETHANOL PARAMETER IN THE PCM

Note: Certain customer fueling practices such as only fueling with small amounts of fuel or repeatedly switching between gasoline and an ethanol blend greater than E15 may prevent the PCM from learning the correct ethanol content in the fuel.

• Reset the keep alive memory (KAM). Refer to Section 2, Resetting The Keep Alive Memory (KAM).

• Ignition ON, engine running.

• Access the PCM and monitor the FF_LRND (MODE) PID.

• Drive the vehicle approximately 11.3 km (7 miles) or until the FF_LRND PID indicates yes.

Is the PID state YES?

Yes	No
GO to HC9 .	GO to HC17 .

HC9 COMPARE THE UPDATED FF_INF PID TO THE CALCULATED PERCENTAGE OF ETHANOL

• Ignition OFF.

• Ignition ON, engine OFF.

• Access the PCM and monitor the FF_INF (PER) PID.

Is the FF_INF PID value within 20% of the calculated percentage of ethanol?

Yes	No
RETURN the vehicle to the customer. ADVISE the customer of the correct fueling practices when using flex fuel. REFER to the Owner's Literature for additional information. ADVISE the customer to continue to use the same fuel for the next 2-3 refuels. This practice helps verify the PCM is learning the correct percentage of ethanol in the fuel.	A fuel system concern may be present, which prevents the PCM from learning the correct percentage of ethanol in the fuel, GO to HC11 .

Yes

RETURN the vehicle to the customer. ADVISE the customer of the correct fueling practices when using flex fuel. REFER to the Owner's Literature for additional information. ADVISE the customer to continue to use the same fuel for the next 2-3 refuels. This practice helps verify the PCM is learning the correct percentage of ethanol in the fuel.

A fuel system concern may be present, which prevents the PCM from learning the correct percentage of ethanol in the fuel,

GO to HC11 .

HC10 DETERMINE IF THE PERCENTAGE OF ETHANOL IN THE FUEL IS LESS THAN 25%

• Check the recorded calculated percentage of ethanol in the fuel.

Is the calculated percentage of ethanol in the fuel less than 25%?

Yes	No
GO to HC11 .	REPAIR as necessary. ADVISE the customer of the correct fuel type required for this vehicle. REFER to the Owner's Literature for additional information. Clear the PCM DTCs. REPEAT the self-test.

Yes

GO to HC11 .

REPAIR as necessary. ADVISE the customer of the correct fuel type required for this vehicle. REFER to the Owner's Literature for additional information.

Clear the PCM DTCs. REPEAT the self-test.

Source reference 5139

2016 Mustang workshop publication supplied to Mustang Atlas. Original technical text and illustrations; HTML formatting by Mustang Atlas. Source page numbering is retained for traceability. Follow the configuration, revision, warnings, and cross-references in the material. About this edition.