Diesel Engine Troubleshooting

General Description

• This control determines the fuel injection quantity by adding coolant temperature, fuel temperature, intake air temperature, and intake air pressure corrections to the basic injection quantity. The engine ECU calculates the basic injection quantity based on the engine operating conditions and driving conditions.

Injection Quantity Calculation Method
• The calculation consists of a comparison of the following two values: 1. The basic injection quantity that is obtained from the governor pattern, which is calculated from the accelerator position and the engine speed. 2. The injection quantity obtained by adding various types of corrections to the maximum injection quantity obtained from the engine speed. The lesser of the two injection quantities is used as the basis for the final injection quantity.

Set Injection Quantities
• Basic Injection Quantity
This quantity is determined by the engine speed and the accelerator opening. With the engine speed constant, if the
accelerator opening increases, the injection quantity increases; with the accelerator opening constant, if the engine speed rises, the injection quantity decreases.

• Starting Injection Quantity
This is determined based on the basic injection quantity for when the engine starts up and the added corrections for the starter S/W ON time, the engine speed, and the coolant temperature. If the coolant temperature is low, the injection quantity is increased. When the engine has completely started up, this mode is cancelled.

• Injection Quantity for Maximum Speed Setting
Determined by the engine speed. The injection quantity is restricted to prevent an excessive rise in engine speed
(overrun).

• Maximum Injection Quantity
This is determined based on the basic maximum injection quantity determined by the engine speed, and the added
corrections for coolant temperature, fuel temperature, intake air temperature, atmospheric temperature, intake air
pressure, atmospheric pressure, and full Q adjustment resistance (only for the 1st generation HP0 system), etc.

Corrections
• Cold Engine Maximum Injection Quantity Correction
When the coolant temperature is low, whether during start-up or during normal operation, this correction increases
the injection quantity.

• Intake Air Pressure Correction
When the intake air pressure is low, the maximum injection quantity is restricted in order to reduce the emission of black smoke.

• Atmospheric Pressure Correction
The maximum injection quantity is increased and decreased according to the atmospheric pressure. When the atmospheric pressure is high, the maximum injection quantity is increased.

• Injection Quantity Delay Correction for Acceleration
During acceleration, if there is a large change in the accelerator pedal opening, the injection quantity increase is delayed in order to prevent black smoke emissions.

• Full Q Adjustment Resistance (Only for 1st Generation HP0 Systems)
The full Q resistance is for correcting the injection quantity for a full load. The maximum injection quantity is increased or decreased by the car manufacturer to match to standards. There are 15 types of full Q adjustment resistance. The appropriate one is selected and used.

The fuel injection timing is controlled by the timing of the current applied to the injectors. After the main injection period is decided, the pilot injection and other injection timing is determined.

Main Injection Timing
– The basic injection timing is calculated from the engine speed (engine speed pulse) and the final injection quantity, to which various types of corrections are added in order to determine the optimal main injection timing.

Pilot Injection Timing (Pilot Interval)
– Pilot injection timing is controlled by adding a pilot interval value to the main injection. The pilot interval is calculated based on the final injection quantity, engine speed, coolant temperature, atmospheric temperature, and atmospheric pressure (map correction). The pilot interval at the time the engine is started is calculated from the coolant temperature and engine speed.

Split Injection
– The purpose of split injection is to improve the startability of a cold engine. Before the conventional main injection takes place, this function injects two or more extremely small injections of fuel.

Multi-Injection Control (Only for Some Models)
– Multi-injection control is when small injections (up to four times) are carried out before and after the main injection in accordance with the state of the main injection and engine operation. This interval (the time A-D in the diagram below) is based on the final injection quantity, engine speed, coolant temperature, and atmospheric pressure (map correction). The interval during start-up is based on the coolant temperature and engine speed.

Idle Speed Control (ISC) System
• The idle speed control system controls the idle speed by regulating the injection quantity in order to match the actual speed to the target speed calculated by the computer. The ISC can be automatic ISC or manual ISC.

Automatic ISC
– With automatic ISC, the engine ECU sets the target speed. The target engine speed varies with the type of transmission (automatic or manual), whether the air conditioner is ON or OFF, the shift position, and the coolant temperature.

Manual ISC
– The idle engine speed is controlled by the setting on the idle setting button at the driver’s seat.

Idle Vibration Reduction Control
– This control reduces engine vibration during idle. To achieve smooth engine operation, it compares the angle
speeds (times) of the cylinders and regulates injection quantity for each individual cylinder in the event of a large difference.

The fuel that is injected from the nozzle turns into finer particles as the fuel injection pressure increases. This improves combustion and reduces the amount of smoke contained in the exhaust gases. Initially, the maximum injection pressure of the in-line pump (A type) and the distributor pump (VE type) was 60 MPa. Due to advancement in high-pressure applications, there are some recently developed fuel injection systems that inject fuel at a pressure of 100 MPa or higher. The second-generation common rail system injects fuel at an extremely high pressure of 180 MPa.

The E-EGR system is an electronically controlled EGR system. The EGR system recirculates a portion of the exhaust
gases into the intake manifold in order to lower the combustion chamber temperature and reduce NOx emissions.
However, operation of the EGR system may reduce engine power output and affect drivability. For this reason, in the
E-EGR system, the engine ECU controls the EGR to achieve an optimal EGR amount.
Operation Conditions Example
– This operates in the operation region fulfilling the starting conditions below (one example).

P0006 Fuel shutoff valve “A” control circuit low voltage
P0007 Fuel shutoff valve “A” control circuit high voltage
P0016 Crankshaft position sensor, cylinder recognition sensor correlation
P0030 A/F sensor heater control circuit
P0031 A/F sensor heater control circuit low voltage
P0032 A/F sensor heater control circuit high voltage
P0036 A/F sensor heater control circuit
P0037 A/F sensor heater control circuit low voltage
P0045 Turbo/supercharger control solenoid open circuit
P0049 Turbo/supercharger overspeed
P0087 Fuel/rail pressure too low
P0088 Fuel/rail pressure too high
P0093 Fuel system leak maximum quantity detection
P0095 Intake air temperature sensor 2, circuit related
P0097 Intake air temperature sensor 2 circuit low voltage
P0098 Intake air temperature sensor 2 circuit high voltage
P0100 Mass Air Flow (MAF) meter, circuit related
P0101 MAF meter circuit range/performance
P0102 MAF meter circuit low input
P0103 MAF meter circuit high input
P0105 Boost pressure sensor, circuit related
P0107 Boost pressure sensor circuit low input
P0108 Boost pressure sensor circuit high input
P0112 Boost pressure sensor 1 circuit low voltage
P0113 Boost pressure sensor 1 circuit high voltage
P0115 Coolant temperature sensor, circuit related
P0117 Coolant temperature sensor circuit low voltage
P0118 Coolant temperature sensor circuit high voltage
P0119 Coolant temperature sensor circuit intermittent operation
P0120 Accelerator position sensor, switch “A” circuit related
P0121 Accelerator position sensor switch “A” circuit range/performance
P0122 Accelerator position sensor switch “A” circuit low voltage
P0123 Accelerator position sensor switch “A” circuit high voltage
P0124 Accelerator position sensor switch “A” circuit intermittent operation
P0168 Fuel temperature too high
P0180 Fuel temperature sensor, “A” circuit related
P0181 Fuel temperature sensor “A” circuit range/performance
P0182 Fuel temperature sensor “A” circuit low voltage
P0183 Fuel temperature sensor “A” circuit high voltage
P0184 Fuel temperature sensor “A” circuit intermittent operation
P0185 Fuel temperature sensor, “B” circuit related
P0186 Fuel temperature sensor “B” circuit range/performance
P0187 Fuel temperature sensor “B” circuit low voltage
P0188 Fuel temperature sensor “B” circuit high voltage
P0189 Fuel temperature sensor, “B” circuit intermittent operation
P0190 Rail pressure sensor, circuit related
P0191 Rail pressure sensor circuit range/performance
P0192 Rail pressure sensor circuit low voltage
P0193 Rail pressure sensor circuit high voltage
P0194 Rail pressure sensor circuit intermittent operation
P0200 Injector open circuit
P0201 Injector open circuit- #1 cylinder
P0202 Injector open circuit- #2 cylinder
P0203 Injector open circuit- #3 cylinder
P0204 Injector open circuit- #4 cylinder
P0205 Injector open circuit- #5 cylinder
P0206 Injector open circuit- #6 cylinder
P0208 Injector open circuit- #8 cylinder
P0217 Engine overheat
P0218 Transmission overheat
P0219 Engine overrun
P0230 Fuel pump, primary circuit related
P0234 Turbo/supercharger overboost
P0237 Boost pressure sensor circuit low voltage
P0263 Cylinder correction quantity error- #1 cylinder
P0266 Cylinder correction quantity error- #2 cylinder
P0269 Cylinder correction quantity error- #3 cylinder
P0272 Cylinder correction quantity error- #4 cylinder
P0275 Cylinder correction quantity error- #5 cylinder
P0278 Cylinder correction quantity error- #6 cylinder
P0299 Turbo/supercharger supercharge deficiency
P0335 Crankshaft position sensor, “A” circuit related
P0339 Crankshaft position sensor “A” circuit intermittent operation
P0340 Cylinder recognition sensor, “A” circuit related
P0400 EGR flow volume abnormality
P0404 EGR control circuit range/performance
P0405 EGR sensor “A” circuit low voltage
P0406 EGR sensor “A” circuit high voltage
P0407 EGR sensor “B” circuit low voltage
P0408 EGR sensor “B” circuit high voltage
P0500 Vehicle speed sensor, “A” circuit related
P0501 Vehicle speed sensor “A” circuit range/performance
P0504 Brake switch “A”, “B” correlation
P0510 Throttle position switch closed
P0524 Engine oil pressure too low
P0540 Intake air heater “A” circuit
P0544 Exhaust gas temperature sensor, circuit related
P0545 Exhaust gas temperature sensor circuit low voltage
P0546 Exhaust gas temperature sensor circuit high voltage
P0560 Battery voltage
P0605 Engine ECU internal malfunction
P0607 Engine ECU internal malfunction
P0611 EDU malfunction
P0617 Starter relay circuit high voltage
P0627 Fuel pump “A” open control circuit
P0686 Engine ECU power supply relay control circuit low voltage
P0704 Clutch switch input circuit abnormality
P0710 Transmission oil temperature sensor, “A” circuit related
P0715 Turbine speed sensor, “A” circuit related
P0753 Shift solenoid “A” actuation related
P0758 Shift solenoid “B” actuation related
P0850 Parking/neutral switch, input circuit related
P2002 Particulate Matter (PM) capture efficiency at or below specified value
P2031 Exhaust gas temperature sensor, circuit related
P2032 Exhaust gas temperature sensor circuit low voltage
P2033 Exhaust gas temperature sensor circuit high voltage
P2047 Exhaust gas fuel addition valve abnormality
P2120 Accelerator position sensor, switch “D” circuit related
P2121 Accelerator position sensor switch “D” circuit range/performance
P2122 Accelerator position sensor, switch “D” circuit low input
P2123 Accelerator position sensor, switch “D” circuit high input
P2125 Accelerator position sensor, switch “E” circuit related
P2127 Accelerator position sensor, switch “E” circuit low input
P2128 Accelerator position sensor, switch “E” circuit high input
P2138 Accelerator position sensor, switch “D”/”E” circuit voltage correlation
P2226 Atmospheric pressure sensor, circuit related
P2228 Atmospheric pressure sensor circuit low voltage
P2229 Atmospheric pressure sensor circuit high voltage

Black smoke: Fuel that has been baked into soot and discharged.

• Black smoke is often referred to as just “smoke”. Black smoke is generated when the injected fuel is poor in oxygen. As the fuel is exposed to high temperatures, thermal breakdown occurs, leaving carbon behind. Black smoke occurs when the injected fuel quantity is too large, or when the air-fuel mixture is rich due to an insufficient quantity of air.

Source of Black Smoke

1 Large Fuel Injection Quantity, Air-fuel mixture becomes rich.
2 Low Intake Air Quantity, Air quantity is insufficient due to air filter clogging.
3 Poor Fuel Atomization, The ratio of fuel to air worsens.
4 Retarded Fuel Injection Timing, Air-fuel mixing time is insufficient.

White smoke: Uncombusted fuel that has been vaporized and then discharged.

• White smoke is generated when combustion occurs at a relatively low temperature, resulting in the exhaust of uncombusted fuel and oil particles. White smoke is most likely to be generated when combustion chamber temperature
is low.

Source of White Smoke

1 Late Injection, Timing Fuel is injected when the piston is in the down stroke.
2 Cold Engine, Ignition occurs late and combustion is prolonged.
3 Poor Fuel Combustibility
4 Rise and Fall of Oil Pressure, Oil undergoes partial thermal breakdown.

When fuel mixed with air during the ignition lag period (from the time injection begins until the fuel is ignited) reaches ignition temperature, the mixture is combusted in one burst. The pressure in the combustion chamber at this time rises as the quantity of the air-fuel mixture increases. If a large amount of air-fuel mixture is created during the ignition lag period, the pressure in the combustion chamber will rise rapidly. The pressure waves resulting from fuel ignition vibrate the cylinder walls and engine components, which generates noise. The generated noise is called “knocking”. To some extent, knocking is unavoidable in engines that use a self-ignition system.

With conventional injection methods, because an excessive quantity of fuel was injected in the initial period, the explosion pressure rose excessively, leading to the generation of noise such as engine knocking sounds. To improve this condition through pilot injection, initially only the necessary and adequate quantity of fuel is injected. At the same time, the combustion chamber temperature is raised, and main injection combustion is assisted while working to prevent noise and vibration.