Description
Water contamination in the fuel system may cause driveability conditions such as hesitation, stalling, no start, or misfires in one or more cylinders. Water may collect near a single fuel injector at the lowest point in the fuel injection system and cause a misfire in that cylinder. If the fuel system is contaminated with water, inspect the fuel system components for rust or deterioration.
Alcohol concentrations of 10 percent or more in the fuel can be detrimental to fuel system components. Alcohol contamination may cause fuel system corrosion, deterioration of rubber components, and subsequent fuel filter restriction. Some types of alcohol are more detrimental to fuel system components than others. Ethanol is commonly used in gasoline, but in concentrations of no more than 10 percent. Some fuels, such as E85, contain a very high percentage of ethanol. Fuel with more than 10 percent ethanol may cause driveability conditions such as hesitation, lack of power, stalling, or no start.
Test Description
Water contamination in the fuel system may cause driveability conditions such as hesitation, stalling, no-start, or misfires in one or more cylinders. Water may collect near a single fuel injector at the lowest point in the fuel injection system and cause a misfire in that cylinder. If fuel system is contaminated with water, inspect fuel system components for rust or deterioration.
Alcohol concentrations of 10 percent or more in the fuel can be detrimental to fuel system components. Alcohol contamination may cause fuel system corrosion, deterioration of rubber components, and subsequent fuel filter restriction. Some types of alcohol are more detrimental to fuel system components than others. Ethanol is commonly used in gasoline, but in concentrations of no more than 10 percent. Some fuels, such as E85, contain a very high percentage of ethanol. Fuel with more than 10 percent ethanol may cause driveability conditions such as hesitation, lack of power, stalling, or no-start.
System Description
The scan tool is first used to energize the fuel pump relay. The fuel injector tester is then used to pulse each injector for a precise amount of time, allowing a measured amount of fuel into the manifold. This causes a drop in system fuel pressure that can be recorded and used to compare each injector.
The number below refers to step number in diagnostic procedure.
- 3 - Engine Coolant Temperature (ECT) must be below operating temperature in order to avoid irregular fuel pressure readings due to hot soak fuel boiling.
Scheme 19
Scan tool first energizes fuel pump and then injectors for a precise amount of time allowing a measured amount of fuel into manifold. This causes a drop in system fuel pressure that can be recorded and used to compare each injector.
The numbers below refer to step numbers in diagnostic procedure.
- 3 - Engine Coolant Temperature (ECT) must be below operating temperature in order to avoid irregular fuel pressure readings due to hot soak fuel boiling.
Fuel tank leak test is used to locate any fuel or fuel vapor escaping fuel tank area. Fuel vapors escaping above fuel level will be detected when Evaporative (EVAP) emission diagnostics complete one test cycle. Malfunction Indicator Light (MIL) will illuminate after EVAP diagnostics complete 2 test cycles.
The numbers below refer to step numbers in diagnostic procedures.
- 1 - Perform this procedure in order to determine that no EVAP diagnostic DTC is present.
- 3 - This test is to locate fuel leakage in fuel lines.
- 4 - This tests for fuel leaks below fuel tank fuel level.
- 5 - This test is to locate fuel vapors escaping above fuel level in fuel tank.
The engine idle speed is controlled by the Idle Air Control (IAC) valve. The IAC valve is on the throttle body. The IAC valve pintle moves in and out of an idle air passage bore to control air flow around the throttle plate. The IAC valve consists of a movable pintle, driven by a gear attached to an electric motor called a stepper motor. The stepper motor is capable of highly accurate rotation, or of movement, called steps. The stepper motor has 2 separate windings that are called coils. Each coil is supplied current by 2 circuits from the PCM. When PCM changes polarity of a coil, the stepper motor moves one step. The PCM uses a predetermined number of counts to determine the IAC pintle position. Observe IAC counts with a scan tool. The IAC counts will increment up or down as the PCM attempts to change the IAC valve pintle position. An IAC reset will occur when the ignition is turned off. First, PCM will seat the IAC pintle in the idle air passage bore. Second, the PCM will retract the pintle a predetermined number of counts to allow for efficient engine start-up. If engine idle speed is out of range for a calibrated period of time, an idle speed DTC sets.
The number below refers to step number in diagnostic procedure.
- 5 - This test will determine the ability of the PCM and IAC valve control circuits to control the IAC valve.
- 7 - This test will determine the ability of the PCM to provide the IAC control valve circuits with a ground. On a normally operating system, the test light should not flash while the IAC Counts are incrementing.