Engine Controls - Diagnostic Methods (Hybrid): Other Ford C-MAX II

VEHICLE CHECK/PREPARATION

Before using the scan tool to carry out any test, refer to the Important Safety Notice located in the Introduction of this article and the necessary visual checks listed below.

Visual Checks

1. Inspect the intake air system.
2. Check all engine vacuum hoses for damage, leaks, cracks, kinks and correct routing.
3. Check the powertrain control module (PCM) or TCM wiring harness for correct connections, bent or broken pins, corrosion, loose wires and correct routing.
4. Examine all high voltage cables and connectors for secure connection, damaged, burned or overheated insulation and loose or broken condition.
5. Verify the high voltage traction battery service plug is correctly connected.
6. Check the PCM, sensors, and actuators for physical damage.
7. Check the engine coolant for correct level and mixture.
8. Check the motor electronics coolant for correct level and mixture.
9. Check the transmission fluid level and quality. Refer to the Automatic Transmission article.
10. Make all necessary repairs before continuing with the quick test. For additional information refer to «QUICK TEST DESCRIPTION»(ref-608997-S09791422472014041200000) .

Vehicle Preparation

1. Carry out all safety steps required to start and run vehicle tests. Apply the parking brake, place the gear selector firmly into the PARK position and block the drive wheels.
2. Verify the high voltage traction battery state of charge is equal to or greater than 45% by monitoring the battery energy control module (BECM) state of charge parameter identification (PID). If the monitored PID displays the state of charge below 45%, start and idle the engine. For additional information refer to «DIAGNOSTIC MODES»(ref-608997-S19647978582014041200000) .
3. Turn off all electrical loads, such as radios, lamps, A/C, blower, and fans.
4. Start the engine and bring it up to the normal operating temperature before running the quick test.

One Touch Integrated Start System

The vehicle is equipped with one touch integrated start system. It may be necessary to disable the one touch integrated start system to carry out diagnostic procedures that require extended cranking. Connect the scan tool, access the PCM and select the one touch integrated start system control PID to disable the system.

Generic OBD PID List

An X in the Freeze Frame column denotes both a mode 1 and mode 2 PID (real time and freeze frame).

CL = Closed loop using HO2S(s) as feedback for fuel control.

OL DRIVE = Open loop due to driving conditions (heavy acceleration).

OL FAULT = Open loop due to fault with all upstream HO2S.

CL FAULT = Closed loop fuel control, but fault with one upstream HO2S.

Ford BECM PID List

Ford PCM PID List

Note. This is not a complete list of Ford PIDs available. This is a list of Ford PIDs in this article.

Ford SOBDMC PID List

Emission Related Freeze Frame Data

Freeze frame data allows access to emission-related values from specific generic parameter identifications (PIDs). These values are stored when an emission related diagnostic trouble code (DTC) is stored in continuous memory. This provides a snapshot of the conditions that were present when the DTC was stored. Once one set of freeze frame data is stored, this data remains in memory even if another emission-related DTC is stored, with the exception of misfire or fuel system DTCs. Once freeze frame data for a misfire or fuel system DTC is stored, it overwrites any previous data, and freeze frame data is no longer overwritten. When a DTC associated with the freeze frame data is erased or the DTCs are cleared, new freeze frame data can be stored again. In the event of multiple emission-related DTCs in memory, always note the DTC for the freeze frame data.

FREEZE FRAME DATA TABLE

Some unique PIDs are stored in the keep alive memory (KAM) of the powertrain control module (PCM) to help in diagnosing the root cause of misfires. These PIDs are collectively called misfire freeze frame (MFF) data. These parameters are separate from the generic freeze-frame data that is stored for every malfunction indicator lamp (MIL) code. They are used for misfire diagnosis only. The MFF data is more useful for misfire diagnosis than the normal diagnosis only. It is captured at the time of the highest misfire rate and not when the DTC is stored at the end of a 1, 000 or 200 revolution block. (Generic freeze-frame data for misfire can be stored minutes after the misfire actually occurred.)

The MFF PIDs are supported on all vehicles, but may not be available on all scan tools because enhanced PID access may vary by scan tool manufacturer.

MISFIRE FREEZE FRAME PIDS

Non-Emission Related Freeze Frame Data

Freeze frame data allows access to non-emission related values from specific manufacturer's PIDs. These values are stored when a non-emission related DTC is stored in continuous memory. This provides a snapshot of the conditions that were present when the DTC was stored. Once one set of freeze frame data is stored, this data remains in memory even if another DTC is stored. When a DTC associated with the freeze frame data is cleared or a KAM reset is carried out, new freeze frame data can be stored again.

NON-EMISSION FREEZE FRAME DATA TABLE

FLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM)

Making Changes To The VID Or TRID Blocks

A PCM or TCM which is programmed may require changes to be made to certain VID or TRID information to accommodate vehicle hardware. Refer to Module Reprogramming on the scan tool.

TRANSMISSION CONTROL MODULE (TCM) REPROGRAMMING

Drive Cycle Recommendations

1. Most OBD monitors complete more readily using a steady foot driving style during cruise or acceleration modes. Operating the throttle in a smooth fashion minimizes the time required for monitor completion.
2. Fuel tank level should be between 1/2 and 3/4 full with 3/4 full being the most desirable.
3. The evaporative monitor can only operate during the first 30 minutes of engine operation. When executing the procedure for this monitor, stay in part throttle mode and drive in a smooth fashion to minimize fuel slosh.
4. When bypassing the EVAP engine soak timer, the PCM must remain powered (ignition in ON position) after the clearing the continuous DTCs and relearning emission diagnostic information.

Recreating The Fault

Recreating the fault is the first step in isolating the cause of the intermittent symptom. A thorough investigation should start with the customer information. If freeze frame data is available, it may help in recreating the conditions at the time of a malfunction indicator lamp diagnostic trouble code (MIL DTC). Listed below are some of the conditions for recreating the fault

CONDITIONS TO RECREATE FAULT

Accumulating PCM Data

PCM data can be accumulated in a number of ways. This includes circuit measurements with a digital multimeter (DMM) or scan tool parameter identification (PID) data. Acquisition of PCM PID data using a scan tool is one of the easiest ways to gather information. Gather as much data as possible when the fault is occurring to prevent incorrect diagnosis. Gather data during different operating conditions and based on the customer description of the intermittent fault. Compare this data with the known good data values located in TYPICAL DIAGNOSTIC REFERENCE VALUES . This requires recording data in four conditions for comparison: 1) KOEO, 2) Hot Idle, 3) 48 km/h (30 MPH), and 4) 89 km/h (55 MPH).

Peripheral Inputs

Some signals may require certain peripherals or auxiliary tools for diagnosis. In some cases, these devices can be inserted into the measurement jacks of the scan tool or DMM. For example, connecting a fuel pressure gauge to monitor and record the fuel pressure voltage reading and capturing the data would help find the fault.

Comparing PCM Data

After the PCM values are acquired, it is necessary to determine the fault area. Typically, it requires the comparison of the actual values from the vehicle to the typical values from the TYPICAL DIAGNOSTIC REFERENCE VALUES .

Analyzing PCM Data

Look for abnormal events or values that are clearly incorrect. Inspect the signals for abrupt or unexpected changes. For example, during a steady cruise most of the sensor values should be relatively stable. Sensors such as the throttle position (TP) or mass airflow (MAF), as well as RPM that changes abruptly when the vehicle is traveling at a constant speed, are clues to a possible fault area.

Look for agreement in related signals. For example, if the APP1 and APP2 are changed during acceleration, a corresponding change should occur in TP1, TP2, LOAD, RPM and MAF PIDs.

Make sure the signals act in correct sequence. An increase in RPM after the TP1 and TP2 are increased is expected. However, if RPM increases without a TP1 and TP2 change, then a fault may exist.

Scroll through the PID data while analyzing the information. Look for sudden drops or spikes in the values.

Obtain Freeze Frame Data

Freeze frame data can be helpful in duplicating and diagnosing adaptive fuel concerns. This data (a snapshot of certain parameter identification [PID] values, recorded at the time the DTC was stored in continuous memory) is helpful to determine how the vehicle was being driven when the fault occurred, and can be especially useful on intermittent concerns. Freeze frame data, in many cases, can help to isolate possible areas of concern as well as rule out others. Refer to FREEZE FRAME DATA for a more detailed description of this data.

Using The LONGFT1 PID

The LONGFT1 PID can be useful for diagnosing fuel trim concerns. A negative PID value indicates the fuel is being reduced to compensate for a rich condition, while a positive PID value indicates the fuel is being increased to compensate for a lean condition. It is important to know there is a separate LONGFT1 value used for each RPM and load point of engine operation. When viewing the LONGFT1 PID, the value may change a great deal as the engine is operated at different RPM and load points. This is because the fuel system may have learned corrections for fuel delivery concerns that can change as a function of engine RPM and load. The LONGFT1 PID displays the fuel trim currently being used at that RPM and load point. Observing these changes in LONGFT1 can help when diagnosing fuel system concerns. For example

1. A contaminated MAF sensor results in a LONGFT1 correction value that is negative at idle (reducing fuel), but positive (adding fuel) at higher RPM and loads.
2. Vacuum leaks result in large, rich corrections (positive LONGFT1 value) at idle, but little or no correction at higher RPM and loads.
3. A plugged fuel filter results in no correction at idle, but large rich corrections (positive LONGFT1 value) at high RPM and load.

Air Measurement System

With this condition, the engine may actually run rich or lean of stoichiometry (14.7:1 air to fuel ratio) if the PCM is not able to compensate enough to correct for the condition. One possibility is the mass of air entering the engine is actually greater than what the mass airflow (MAF) sensor is indicating to the PCM. For example, with a contaminated MAF sensor, the engine runs lean at higher RPM because the PCM delivers fuel for less air than is actually entering the engine.

Vacuum Leaks And Unmetered Air

With this condition, the engine may actually run lean of stoichiometry (14.7:1 air to fuel ratio) if the PCM is not able to compensate enough to correct for the condition. This condition can be caused by unmetered air entering the engine, or due to a MAF concern. In this situation, the volume of air entering the engine is actually greater than what the MAF sensor is indicating to the PCM. Vacuum leaks normally are most apparent when high manifold vacuum is present (for example, during idle or light throttle). If freeze frame data indicates the fault occurred at idle, a check for vacuum leaks and unmetered air might be the best starting point.

For example, loose, leaking or disconnected vacuum lines, intake manifold gaskets or O-rings, throttle body gaskets, brake booster, air inlet tube, stuck or frozen or aftermarket PCV valve, and unseated engine oil dipstick.

Insufficient Fueling

With this condition, the engine may actually run lean of stoichiometry (14.7:1 air to fuel ratio) if the PCM is not able to compensate enough to correct for the condition. This condition can be caused by a fuel delivery system concern that restricts or limits the amount of fuel being delivered to the engine. This condition normally is most apparent when the engine is under a heavy load and at high RPM, when a higher volume of fuel is required. If the freeze frame data indicates the fault occurred under a heavy load and at higher RPM, a check of the fuel delivery system (checking fuel pressure with engine under a load) might be the best starting point.

For example, low fuel pressure, fuel pump, fuel filter, fuel leaks, restricted fuel supply lines, and fuel injector concerns.

Exhaust System Leaks

In this type of condition, the engine may actually be running rich of stoichiometry (14.7:1 air to fuel ratio) because the fuel control system is adding fuel to compensate for a perceived (not actual) lean condition. This condition is caused by oxygen (air) entering the exhaust system from an external source. The HO2S reacts to this exhaust leak by increasing fuel delivery. This condition causes the exhaust gas mixture from the cylinder to be rich.

For example, exhaust system leaks upstream or near the HO2S, and poorly welded or leaking HO2S boss.

With this condition, the engine may actually run rich or lean of stoichiometry (14.7:1 air to fuel ratio) if the PCM is not able to compensate enough to correct for the condition. One possibility is the mass of air entering the engine is actually less than what the MAF sensor is indicating to the PCM. For example, with a contaminated MAF sensor, the engine runs rich at idle because the PCM delivers fuel for more air than is actually entering the engine.

Fuel System

With this condition, the engine may actually run rich of stoichiometry (14.7:1 air to fuel ratio) if the PCM is not able to compensate enough to correct for the condition. This situation can be caused by a fuel delivery system that is delivering excessive fuel to the engine.

For example

1. EVAP purge valve leak (if canister is full of vapors, introduces extra fuel).
2. fuel injector leaks (injector delivers extra fuel).
3. fuel pressure regulator causes excessive fuel pressure (system rich at all airflows), fuel pressure is intermittent, going to pump deadhead pressure, then returning to normal after the engine is turned off and restarted)

Base Engine

Engine oil contaminated with fuel can contribute to a rich running engine.