General scheme of the fuel injection system (MFI) engine 2.4 l (EOBD type).
1 - front oxygen sensor, 2 - throttle position sensor, 3 - camshaft position sensor, 4 - crankshaft position sensor, 5 - coolant temperature sensor, 6 - knock sensor, 7 - intake manifold absolute pressure sensor, 8 - rear oxygen sensor, 9 - fuel injector, 10 - ignition coil, 11 - idle speed control servo, 12 - canister purge solenoid valve, a - to the fuel tank, b - adsorber, c - fuel pressure regulator, d - forced ventilation valve crankcase, e - from the fuel pump, f - positive crankcase ventilation hose, g - air filter, h - pre-catalytic converter (on the exhaust manifold), i - main catalytic converter (under the car floor).
Note: the signals of the marked components are used by the electronic control unit (signals from the ignition switch, starter interlock switch are also used (models with automatic transmission), vehicle speed sensor, fluid pressure switch in the power steering hydraulic system, ignition system, air conditioner switch signal, battery voltage is taken into account); noted "**" components are executive devices (together with the main relay of the injection system, the relay of the electromagnetic clutch of the air conditioning compressor; in addition, from the electronic engine control unit (models with automatic transmission) or an electronic control unit for the engine and automatic transmission (models with automatic transmission) output signals to control the fuel pump, ignition timing and self-diagnostic system).
General scheme of the fuel injection system (MFI) engine 2.7 l (EOBD type).
1 - front oxygen sensor, 2 - mass air flow sensor, 3 - intake manifold air temperature sensor, 4 - coolant temperature sensor, 5 - throttle position sensor, 6 - camshaft position sensor, 7 - crankshaft position sensor, 8 - knock sensor, 9 - rear oxygen sensor, 10 - fuel injector, 11 - ignition coil, 12 - idle speed control servo, 13 - canister purge solenoid valve, a - electronic engine control unit, b - output signal, c - input, d - fuel pump relay, e - engine control relay, f - ignition switch, g - fuel pressure regulator, h - fuel filter, i • air filter, j - two-way valve, k - adsorber, I - preliminary catalytic converter (on the exhaust manifold), m - fuel tank, n - main catalytic converter (under the car floor); A - tachometer signal, B - vehicle speed sensor signal, C - air conditioner switch signal, D - air conditioner compressor electromagnetic clutch relay signal, E - mode relay signal "HI" air conditioner condenser fan motor, F - mode relay signal "LO" air conditioner condenser fan electric motor, TCM - automatic transmission electronic control unit, TCS - traction control electronic control unit.
Note: the signals of the marked components are used by the electronic control unit (signals from the ignition switch, starter interlock switch are also used (models with automatic transmission), fuel pump relay, vehicle speed sensor, air conditioning switch signal is used, battery voltage is taken into account); noted "**" components are executive devices (together with the main relay of the injection system, the relay of the electromagnetic clutch of the air conditioning compressor; in addition, the engine control unit provides output signals to control the fuel pump, ignition timing and self-diagnosis system).
General information
1. Type of electronic engine control unit.
- A) On models with engines of 2.0 l and 2.4 l, an electronic engine control unit developed by MELCO was installed (Mitsubishi Electric Co).
- b) On models with a 2.7 liter engine, electronic engine control units developed by Siemens were installed.
- V) Depending on the export region, units with a standard control system based on signals from two oxygen sensors could be installed (with EOBD) and with a simplified control system based on the signals of one oxygen sensor (without EOBD). On all such models, a catalytic converter was installed.
2. Diagnostic connectors.
One standard 16-pin main diagnostic connector was installed in the car.
3. Type of self-diagnosis system.
- A) An EOBD or OBD-II standard self-diagnosis system is used. The standard diagnostic code consists of one letter and 4 digits (For example: "P0000"). The numbering of such codes is continuous, i.e. fault codes for various systems are not repeated.
- b) If a malfunction is detected, the self-diagnosis system will record the appropriate diagnostic code and record the current parameters of the main components and engine systems at the moment ("freeze frame data"). This data, read by the tester, can make it easier to analyze the fault conditions.
4. Features of diagnostics using a tester.
- A) The algorithm of the Hyundai diagnostic system may differ from the standard algorithm (OBD II protocol), therefore it is recommended to use a Hi-Scan tester to perform a correct diagnosis (Pro).
- b) It is recommended to connect the tester with the ignition off, as when the ignition is on, a malfunction may occur in the electronic engine control unit.
- V) Before connecting the tester to the diagnostic socket, make sure that the condition and shape of the connector pins are correct.
5. Explanations on the operation of the indicator "CHECK ENGINE":
- A) The indicator lights up for a few seconds immediately after the ignition is turned on to indicate that the indicator itself is functioning properly.
- b) Further (after starting or with the engine running) indicator lights up to alert the driver that a malfunction has been detected by the self-diagnosis system.
Attention: if the indicator lights up due to a malfunction of the electronic control unit, then communication between the tester and the electronic control unit cannot be established, and there is no possibility to read diagnostic codes.
- V) Periodic blinking of the indicator indicates the presence of a temporary malfunction. It may continue as long as a major fault affects the emission control system or other systems (e.g. skipped flashes damage the catalytic converter).
- G) In the event of a critical failure (a serious defect in the fuel injection or emission control system) the indicator will remain lit while the vehicle is moving until the fault code is cleared after the fault has been corrected (those. after repair).
Note: Clearing the DTC is not a troubleshooting.
- d) The indicator will turn off when the ignition is turned off (ignition key in position "OFF" (OFF)).
6. Conditions under which the indicator is lit "CHECK ENGINE" may go out at the signal of the electronic control unit when the ignition is on (fault code stored):
- A) For a fault in the transmission: if the engine control unit has not detected a fault during three consecutive vehicle driving cycles under the appropriate modes and conditions (see code occurrence conditions).
- b) For a fault in the exhaust emission system (skip flashes in cylinders): if the ECM does not detect a fault during the cycle under similar engine operating conditions (engine speed, coolant temperature, etc.), at which the fault was first detected.
7. Fault code (for fuel injection system) can be automatically deleted from the memory of the electronic engine control unit with the ignition on, if the corresponding malfunction has not been detected within 40 subsequent vehicle driving cycles.
8. Explanations on the operation of the self-diagnosis system.
- A) Engine control unit monitors input/output signals (some permanently, others only under certain conditions). If a permanent or for a predetermined period of time a violation in the operation of the system is detected, or if after the first incorrect signal the electronic engine control unit received several more similar signals, the electronic engine control unit will perceive this as a malfunction and write the corresponding fault code to memory and send a signal to the output of the self-diagnosis system.
Note:
- Usually, if the electronic control unit has detected a malfunction, then the indicator "CHECK ENGINE" will light up and the fault code will be stored only after the engine is restarted and the same fault is detected again (those. if the fault persists for two consecutive driving cycles).
- For some faults (for example codes P0300, P0301, P0302, P0303, P0304, P0305 and P0306) indicator "CHECK ENGINE" will light up and a fault code will be stored at their first detection, if this fault is critical (catalytic converter is damaged). If the omission of flashes in the cylinders leads only to an increase in exhaust gas toxicity (over 150% of the norm), then a fault code of type P030x is recorded immediately, and the control lamp lights up when the fault is re-detected.
- When some malfunctions occur (for example, codes: P0230, P0325, P0506 and P0507) indicator "CHECK ENGINE" does not light up.
Relationship between fault codes and the nature of the road test for an EOBD type system.
Note:
- "Engine warm-up cycle" means adequate operation of the vehicle engine, in which the temperature of the coolant rises from a value of at least 4.4°C when starting the engine to a value of at least 70°C.
- "Vehicle driving cycle" consists of starting the engine and running the engine after the start of air-fuel ratio feedback control ("closed-loop").
- b) Since the storage device (RAM of the electronic engine control unit) is powered directly from the battery, the diagnostic results are stored even when the ignition key is turned to the "OFF" (OFF). Trouble codes will be cleared when the battery terminal or ECU connector is disconnected. In addition, fault codes are erased if, with the ignition on, (key in position "ON" (ON)) a signal will be sent from the tester to the electronic engine control unit to clear the trouble codes.
Attention: if with the ignition on (key in position "ON" (ON)) disconnect the connector of any sensor, then the electronic control unit will perceive this as a malfunction and the corresponding code will be written to the memory of the electronic control unit. In this case, clear the trouble codes.
Search for basic faults by their symptoms
1. Identification of the causes of engine malfunctions should always begin with a check of the operability of the main systems. If one of the following problems is present: engine does not start, unstable idling speed, poor throttle response (poor acceleration), then start checking the following main systems:
- A) Power supply system (battery, fusible link, fuse).
- b) Connection wires with "weight".
- V) Fuel supply system (fuel lines, fuel filter, fuel pump).
- G) Ignition system (spark plugs, high voltage spark plug wires, ignition coil).
- d) Toxicity reduction system (forced crankcase ventilation system, tightness of vacuum lines).
- e) Other malfunctions (ignition timing, idle speed).
2. Very often the cause of a malfunction of the multipoint fuel injection system (MR) is a bad contact in the connectors. Be sure to check all connectors and make sure they are securely connected.
3. See the appropriate table for troubleshooting.
Engine does not start:
- A. The crankshaft of the engine is not scrolled by a starter.
- B. The starter turns the crankshaft, but the engine does not start.
- B. Incomplete combustion of fuel.
Difficulty starting:
- D. Long scrolling of the Honanaioiu engine shaft with a starter.
- D. Always.
- E. When the engine is cold.
- G. When the engine is warm.
Abnormal idling:
- 3. Incorrect idle speed during warm-up.
- I. Too high idle speed.
- K. Stishkom low idle.
- K. Uneven engine operation.
- M. Inadequate engine response to control input or poor throttle response.
Abnormal operation of the engine while driving:
- H. Vehicle jerking and jerking.
- O. Detonation.
Engine stalls:
- P. Shortly after the start.
- P. After depressing the accelerator pedal.
- C. After releasing the accelerator pedal.
- T. When turning on the air conditioner
Other faults:
- U. Increased fuel consumption.
- F. The engine is overheating.
- X. Engine does not warm up.
4. If there are difficulties with refueling (overflow, sloshing fuel out of the tank), check the fuel cutoff valve, fuel tank vent valve hose, and EVAP filter.
Features of checking the fuel injection system
1. If the components of the fuel injection system (sensors, electronic engine control unit, injectors, etc.) are faulty, the result will be a cut in fuel supply or a failure in accurate fuel supply under various engine operating conditions.
The following situations may occur:
- A) The engine does not start or starts with difficulty.
- b) Unstable operation of the engine at idle.
- V) Poor engine control.
2. If any of the above situations occur, then first carry out the normal diagnostic procedure, which includes basic engine checks (no malfunction of the ignition system, incorrect engine settings, etc). Then check the fuel injection system components (MFI) using a tester according to subsection "Standard troubleshooting chart with a tester".
Note:
- Before removing or installing any component, first read the DTCs and then disconnect the cable from the negative battery terminal.
- Before disconnecting the wires from the battery terminals, set the ignition key to the position "OFF" (OFF). Disconnecting or connecting the battery terminal wires with the ignition on or the engine running can damage the engine control module.
- The wires of the control system connecting the electronic engine control unit with the oxygen sensor are shielded using a wire connecting to "weight", which is connected to the body to eliminate the effects of interference from the ignition system and the radio. If the shield wire is defective, replace the engine control assembly wiring.
- Do not disconnect the wire from the positive battery terminal when checking the alternator, otherwise the engine control unit may be damaged.
- When charging the battery from an external source, disconnect the wires of the battery terminals on the vehicle to prevent damage to the engine control unit.
Standard troubleshooting chart with a tester
1. Simulate symptoms of a malfunction to check for their presence and determine the nature and conditions of occurrence (engine operating mode, operating conditions, etc.).
2. Read the fault codes and determine the causes of the fault, the components to be tested and the order in which they should be tested.
3. Check the input signals of the electronic engine control unit using a tester or motor tester. If the signals are normal, then the corresponding sensor (element) serviceable. Move on to the next component.
4. Check the output signals of the electronic engine control unit using a motor tester and check the operation of the actuators (drives) using the ACTUATOR TEST item of the tester. If the signals of the engine control unit and the drive are normal, then the drive control is normal. Move on to the next component.
5. If the signals of the electronic engine control unit are normal, then check and, if necessary, repair the electrical wiring of the system components. After repair, check the signals of the electronic engine control unit again. If the signals are OK this time, check the input and output signals for the next component to be tested.
6. If the wiring is in order, but the input and output signals of the engine control unit are not correct, then check the individual components of the system and. if necessary, repair or replace them. After repair, check the signals of the engine control unit again. If this time the signals check the signals for the next component to be tested.
7. Recheck for symptoms and repair.
If, as a result of checking the suspect wiring circuit and specific components, no defects are found, but the input and output signals of the engine control unit deviate from the norm, then carefully evaluate the symptoms of the malfunction (the initial diagnosis may have been incorrect or incomplete). When checking further, try to expand the troubleshooting area to other groups of components (repair if necessary).
8. Try to simulate the symptoms of the problem to be sure that the problem has been fixed. Eliminate the cause of the malfunction to prevent the defect from reappearing.
Table. Troubleshooting by their symptoms (the number shows the test sequence).
Checking the indicator "CHECK ENGINE" ("check the engine")
1. Turn on the ignition (key position "ON" (ON)) and make sure the indicator "CHECK ENGINE" lights up for about 5 seconds and then goes out.
2. If the indicator does not light, then check the wiring, fuse and indicator lamp.
Reading trouble codes
1. Prepare the vehicle for inspection as follows.
- A) Make sure the battery is in good condition, as fault detection is not possible when the battery voltage is low.
- b) Turn off all additional equipment.
- V) Set the manual transmission shift lever to the neutral position or the automatic transmission selector lever to the position "N".
Attention: do not disconnect the battery until the diagnostic results are completely read, as the fault code will be deleted from the memory of the electronic control unit when the battery or the connector of the electronic engine control unit is disconnected.
2. When checking with a tester, connect the tester to the diagnostic socket located under the bottom cover of the instrument panel.
Attention: before connecting or disconnecting the tester, turn off the ignition.
3. Turn on the ignition and read the diagnostic codes.
4. Description of the structure of a standard diagnostic trouble code for an OBD-II type system.
- A) The letter shows the purpose (application area) faulty device: P - transmission (engine and gearbox), C - chassis, B - body, U - on-board electrical network.
- b) The first digit of the code after the letter indicates either a group of common SAE codes (0) or a group of specialized manufacturer codes (1).
- V) The second digit of the code after the letter indicates the specific vehicle system in which the malfunction is present. For example, if the application is transmission (R), then the following 8 systems are defined for it: 1 - fuel system and air supply system, 2 - fuel system and air supply system (only types of malfunctions in the injector circuit), 3 - ignition system or misfire in cylinders, 4 - additional emission control system (emission), 5 - vehicle speed control system and idle speed control system, 6 - circuits of various electronic control systems, 7 and 8 - transmission (Transmission).
- G) The remaining 2 digits indicate the specific component of the system.
Erasing fault codes without a tester
Note: after performing the repair, delete the trouble codes from the memory of the electronic control unit.
1. Turn off the ignition (key in position "OFF" (OFF)).
2. After disconnecting the wire from the negative battery terminal for 15 seconds or more, reconnect the wire to the terminal.
3. Start the engine and after warming up, let it idle for 15 minutes or more.
4. With the ignition on, read the trouble codes and make sure that a normal status code is issued.
Recommendations for troubleshooting by codes
1. Before looking for the cause of the malfunction, check that the battery voltage is 10V or more, then check the circuit "masses" engine control unit.
2. If the DTC continues to appear even though testing has shown that the systems/circuits being tested are OK (no faults found), substitute a known-good ECM, perform a road test, and recheck.
3. Replace the engine control unit with a new one only after checking the voltage at its outputs to confirm that there is no open or short circuit in the circuits.
4. If the diagnostic code is not issued (with a good diagnostic circuit) and the engine stalls or the engine does not start, replace the engine control unit with a new one.
5. For most items diagnosed using codes, the main causes of the malfunction are:
- A) Corresponding element defect (specified in code detail, see code table);
- b) Poor contact in the cell connector, broken wiring or short circuit in the cell circuit (power chains, "masses", signal);
- V) Defective electronic engine control unit.
Explanations on the operation of the system in emergency mode
When the self-diagnosis system detects a critical malfunction of one of the main sensors, the engine management system switches to emergency control mode (LIMP HOME FUNCTION), replacing the incorrect signal with the signal previously stored in the memory of the signal control unit so that the car can continue moving (to the station service).
1. If the air flow sensor is faulty:
- A) Signals from the throttle position sensor are used for control (if serviceable), crankshaft position sensor (engine crankshaft speed), air temperature sensor in the intake manifold in accordance with a given program.
- b) The idle speed control servo is fixed in the programmed position, as a result, idle speed control is not performed.
2. If the intake manifold air temperature sensor is faulty, the intake manifold air temperature is calculated using the signals from the coolant temperature sensor.
3. If the throttle position sensor is faulty, then there is no increase in fuel supply when the accelerator pedal is pressed (signal from the throttle position sensor). For control, signals are used from the absolute pressure sensor, the air temperature sensor in the intake manifold and the position of the idle speed control servo.
4. If the coolant temperature sensor is faulty, the temperature is calculated depending on the signals from the intake manifold air temperature sensor.
5. If a misfire is detected in any cylinder, the fuel supply to that cylinder is stopped.
6. If the oxygen sensor is faulty (models with one sensor) or front oxygen sensor (models with two or four sensors), then the air-fuel ratio is not regulated (no feedback control).
7. (Models with EOBD system) If the rear oxygen sensor is faulty, then air-fuel ratio control (feedback control) is made taking into account the signals from the front oxygen sensor only.
8. If the camshaft position sensor is faulty, then a later ignition timing is set and sequential fuel injection begins according to the signals from the crankshaft position sensor.
9. If the fuel balance is wrong (codes P0170 - P0173), then the adsorber is not purged.
10. If the knock sensor is faulty, then the ignition timing is corrected only by the signals of the crankshaft position sensor and the air flow sensor.
11. If the idle speed control servo is faulty (codes P1505 - P1508 for a 2.7 liter engine), then the idle speed is controlled according to a given program without a servo drive, depending on the signals from the crankshaft position sensor and the throttle position sensor.
Table. Troubleshooting by diagnostic codes.
Note:
- Models with EOBD:
- 2.0L/2.4L engines: models with two (front and rear) oxygen sensors.
- 2.7L engine: models with four (two front and two rear - for the right and left cylinder heads) oxygen sensors.
- Models without EOBD:
- 2.0L/2.4L engines: models with one (in front of him) oxygen sensor.
- 2.7L engine: models with two (In front of them) oxygen sensors.