Diagnosing signs of engine management system malfunctions (Chevrolet Captiva 1)

Important Preliminary Checks

Important: Some symptoms require a thorough visual/physical inspection. Always perform a visual/physical inspection first. Visual inspections can lead to the problem being corrected without further inspections and save valuable time.

Step	Operation	Values	Yes	No
1	Conduct a diagnostic system check. Are any diagnostic codes (DTCs) stored in the engine control module (ECM) memory?	-	Jump to the appropriate diagnostic trouble code table	Jump to operations 2
2	Check all ECM ground connections. Check all vacuum hoses for cracks, kinks and secure connections. Check for air leaks at all intake manifold sealing surface attachment points. Check all ignition wires for kinks, stiffness, proper routing and signs of breakdown. Inspect the wiring harness for loose connections, pinched connections, or cuts. Are all checks complete?	-	Jump to the corresponding symptom table	-

Intermittent faults; Intermittent fault codes

Definition: The problem may or may not light up the fault indicator light or save the diagnostic fault code.

Important: Do not use the Diagnostic Trouble Code (DTC) charts for intermittent faults. The fault must be present to isolate the problem. If the fault is intermittent, using the DTC charts may result in replacement of functional parts.

Step	Operation	Values	Yes	No
1	Have important preliminary checks been completed?	-	Jump to operations 2	Go to section "Important Preliminary Checks"
2	Conduct a thorough check of questionable chains. Check the connection of the connector parts or the fit of the terminals in the connector body. Check for deformation or damage to the terminals. Check for weak connections between terminals and wires. To check, remove the terminal from the connector body. Are there any problems?	-	Jump to operations 3	Jump to operations 4
3	Repair electrical connectors if necessary. Is the renovation finished?	-	The system is normal	-
4	Perform a road test with a voltmeter connected to the suspect circuit or with a scan tool connected to the diagnostic connector. Did the voltmeter or scan tool show an abnormal voltage or scan value?	-	Jump to operations 5	Jump to operations 6
5	Replace the sensor for the circuit for which the DTC was stored. Is the renovation finished?	-	The system is normal	-
6	Does the fault indicator light indicate a non-permanent fault or is a diagnostic fault code set?	-	Jump to operations 7	Jump to operations 8
7	Check the condition of the relay, ECM-controlled solenoid valve, and switches. Check the correct installation of electrical devices such as lights, radio transmitters, electric motors, etc. Check the ignition control wires for proper routing (away from ignition wires, ignition system components and generator). Check for a short to ground in the circuit of the malfunction indicator lamp or the "test" terminal of the diagnostic connector. Check all ECM ground connections. Correct or repair the relevant circuits as necessary. Is the renovation finished?	-	The system is normal	-
8	Check the diagnostic trouble code memory. Disconnect the throttle position sensor. Let the engine idle until the malfunction indicator lamp comes on. Turn off the ignition. Is DTC P0122 stored in memory?	-	Jump to operations 10	Jump to operations 9
9	Replace the ECM. Is the renovation finished?	-	The system is normal	-
10	Does your car stall while driving?	-	Jump to operations 11	Jump to operations 12
11	Check the duration of the reference pulse of the injectors and the oxygen sensor using a scanning device. Scan tool shows constant low voltage (about 0 mV) for the oxygen sensor at a given value of the duration of the reference pulse supplied by the control module to the injector?	8 msec	Jump to operations 9	Jump to operations 12
12	Check for open diode in air conditioner clutch and other open diodes. If necessary, repair or replace components. Is the renovation finished?	-	The system is normal	-

Difficult start

Definition: The engine cranks normally, but the engine does not start for a long time. The engine runs occasionally or may start and then immediately stall.

Important: Ensure that the starting circuit uses the correct starting procedure. Check for service bulletin updates before diagnosing.

Step	Operation	Values	Yes	No
1	Have important preliminary checks been completed?	-	Jump to operations 2	Go to section "Important Preliminary Checks"
2	Connect the scanning tool to the diagnostic connector. Using a scan tool, check the coolant temperature sensor and the intake air temperature sensor. Compare coolant temperature and intake air temperature with ambient temperature when the engine is cold. Do the coolant temperature and intake air temperature sensor readings differ from the ambient temperature by more than the specified value?	5°F (3°C)	Jump to operations 3	Jump to operations 4
3	Measure the resistance of the coolant temperature sensor and the intake air temperature sensor. Compare the resistance value to the specifications using the Temperature and Resistance Comparison Tables for DTCs P0118 and P0113. If the resistance is not the same, replace the faulty sensor. Is the renovation finished?	-	The system is normal	-
4	Check for a stuck throttle shaft or limiter linkage that may cause the throttle position sensor signal to be high. Repair or replace as necessary. Check the signal level from the throttle position sensor with the throttle valve closed. Is the measured signal level within the set value?	0.4-0.8 V	Jump to operations 5	Jump to operations 26
5	Check the response and accuracy of the manifold absolute pressure sensor. Replace the manifold absolute pressure sensor if necessary. Is the renovation finished?	-	The system is normal	Jump to operations 6
6	Check the operation of the fuel pump. Does the fuel pump run for the set time when the ignition key is turned on?	2 sec.	Jump to operations 7	Go to section "Checking the electric fuel pump relay circuit"
7	Check the pressure in the fuel supply system. Is the fuel pressure within specifications?	410 kPa	Jump to operations 8	Jump to operations 27
8	Check for water in the fuel. Is the fuel contaminated?	-	Jump to operations 9	Jump to operations 10
9	Replace contaminated fuel. Is the renovation finished?	-	The system is normal	-
10	Check the fuel injector driver circuit. Disconnect the wiring harness connectors from all fuel injectors. Connect the injector test light between the wiring harness terminals of each fuel injector connector. Pay attention to the indicator lamp when turning the crankshaft. Is the indicator light flashing on all connectors?	-	Jump to operations 13	Jump to operations 11
11	Check the fuel injector driver wiring harness, connectors and connector terminals for proper contact. Malfunction detected?	-	Jump to operations 12	Jump to operations 28
12	Repair the wiring harness, connector, or connector terminal as necessary. Is the renovation finished?	-	The system is normal	-
13	Measure the resistance at each fuel injector. Is the fuel injector resistance within the specified value (68°F [20°C] - resistance increases slightly at higher temperatures)?	11.6-12.4 Ohm	Jump to operations 15	Jump to operations 14
14	Replace the fuel injector with resistance that does not meet specifications. Is the renovation finished?	-	The system is normal	-
15	Conduct diagnostics of injectors. Malfunction detected?	-	Jump to operations 16	Jump to operations 17
16	Replace clogged or leaking fuel injectors as necessary. Is the renovation finished?	-	The system is normal	-
17	Check for proper ignition voltage output at each cylinder using a spark tester. Check spark plugs for cracks, wear, improper gap, burnt electrodes or heavy deposits. Check ignition wires for short circuits. Check all ignition ground wires for loose connections. Check the accuracy of the ECM controller. Malfunction detected?	-	Jump to operations 18	Jump to operations 19
18	Repair or replace faulty ignition components. Is the renovation finished?	-	The system is normal	-
19	Is your engine misfiring or cutting fuel under load or at idle?	-	Go to section "Checking the ignition system"	Jump to operations 20
20	Does the engine start but then immediately stall?	-	Jump to operations 21	Jump to operations 23
21	Remove the crankshaft position (CKP) sensor. Check for faulty connections and repair if necessary. Malfunction detected?	-	Jump to operations 22	Jump to operations 25
22	Repair faulty connections if necessary. Is the renovation finished?	-	The system is normal	-
23	Check valve synchronization. Check the cylinder compression. Check valve lifters, rocker arms, valve springs and camshaft lobes for excessive wear. Check the intake manifold and exhaust manifold passages for burrs. Malfunction detected?	-	Jump to operations 24	Jump to operations 25
24	If necessary, repair or replace components. Is the renovation finished?	-	The system is normal	-
25	Check the operation of the idle speed control system. Repair or replace components as necessary. Is the renovation finished?	-	The system is normal	-
26	Check the throttle position sensor circuit for proper operation. Repair or replace components as necessary. Is the renovation finished?	-	The system is normal	-
27	Repair the fuel system if necessary. Is the renovation finished?	-	The system is normal	-
28	Replace the ECM. Is the renovation finished?	-	The system is normal	-

Pops or shots in the silencer

Definition: Change in engine power with a constant throttle or cruise control position. The vehicle speeds up and down without changing the position of the gas pedal.

Important: The driver must thoroughly understand the operation of the air conditioning compressor as described in the owner's manual.

The speedometer reading and the speed reading on the scan tool should be the same.

Before diagnosing, check for service bulletin updates.

Step	Operation	Values	Yes	No
1	Have important preliminary checks been completed?	-	Jump to operations 2	Go to section "Important Preliminary Checks"
2	Connect the scanning tool to the diagnostic connector. Does the oxygen sensor (O2S) respond quickly to different throttle positions?	-	Jump to operations 4	Jump to operations 3
3	Check the O2S sensor for silicone or other fuel contamination or use an appropriate sealant. Replace the contaminated O2S sensor. Is the renovation finished?	-	The system is normal	-
4	Test drive the vehicle at a speed at which the malfunction occurs. Check the long term fuel trim readings with a scan tool. Is the long term fuel trim reading within the set value?	-20-20%	Jump to operations 7	Jump to operations 5
5	Long Term Fuel Trim reading below set value?	-20%	Go to section "Diagnostic information about trouble code P2178"	Jump to operations 6
6	Long Term Fuel Trim reading above set value?	20%	Go to section "Diagnostic information about trouble code P2177"	-
7	Check the pressure in the fuel supply system under the existing condition. Is the fuel pressure within specifications?	410 kPa	Jump to operations 8	Jump to operations 17
8	Check the built-in fuel filter. Is the filter dirty or clogged?	-	Jump to operations 18	Jump to operations 9
9	Conduct diagnostics of injectors. Did the injector diagnostics reveal the problem?	-	Jump to operations 19	Jump to operations 10
10	Check for proper ignition output voltage using a spark tester. Check spark plugs for cracks, wear, improper gap, burnt electrodes or heavy deposits. Malfunction detected?	-	Jump to operations 11	Jump to operations 12
11	Repair or replace ignition system components as necessary. Is the renovation finished?	-	The system is normal	-
12	Check the grounding of the ECM controller - cleanliness, tightness of the connection and correct positioning. Check vacuum hoses for kinks or leaks. Malfunction detected?	-	Jump to operations 13	Jump to operations 14
13	Repair electrical components of vacuum lines if necessary. Is the renovation finished?	-	The system is normal	-
14	Check the generator output voltage. Is the generator voltage within the set value?	12-16 V	Jump to operations 16	Jump to operations 15
15	Repair the generator. Is the renovation finished?	-	The system is normal	-
16	Check for unstable operation of the exhaust gas recirculation valve. If necessary, repair or replace components. Is the renovation finished?	-	The system is normal	-
17	Repair the fuel system if necessary. Is the renovation finished?	-	The system is normal	-
18	Replace the fuel filter. Is the renovation finished?	-	The system is normal	-
19	Replace clogged or leaking fuel injectors. Is the renovation finished?	-	The system is normal	-

Lack of power and throttle response, soft pedal effect

Definition: The engine produces less power than expected. The vehicle accelerates little or not at all when the accelerator pedal is not fully depressed.

Step	Operation	Values	Yes	No
1	Have important preliminary checks been completed?	-	Jump to operations 2	Go to section "Important Preliminary Checks"
2	Ensure that the customer's complaint is confirmed. Compare the characteristics of the customer's car with the characteristics of the same car. Is there a problem?	-	Jump to operations 3	The system is normal
3	Inspect the air filter for excessive contamination. Replace the air filter if necessary. Check the gearbox shift pattern and downshifting. Is the gearbox working properly?	-	Jump to operations 4	Jump to operations 5
4	Check the pressure in the fuel supply system. Is the fuel pressure within specifications?	410 kPa	Jump to operations 7	Jump to operations 6
5	Repair the gearbox if necessary. Is the renovation finished?	-	The system is normal	-
6	Repair the fuel system if necessary. Is the renovation finished?	-	The system is normal	-
7	Check for clogged fuel filter or contaminated fuel. Malfunction detected?	-	Jump to operations 8	Jump to operations 9
8	If necessary, repair or replace components. Is the renovation finished?	-	The system is normal	-
9	Check the ignition output voltage at each cylinder using a spark tester. Check the ignition adjustment. Is the ignition system working properly?	-	Jump to operations 10	Jump to operations 11
10	With the engine at normal operating temperature, connect a vacuum gauge to the intake manifold vacuum port. Let the engine run at 1000 rpm. Record the vacuum values. Increase engine speed to 2500 rpm. Record the vacuum reading at 2500 rpm. Does the vacuum decrease by more than the set value?	10 kPa (3 inches Hg)	Jump to operations 12	Jump to operations 15
11	Repair or replace ignition system components as necessary. Is the renovation finished?	-	The system is normal	-
12	Check the exhaust system for clogged, faulty or crumpled pipes. Malfunction detected?	-	Jump to operations 13	Jump to operations 14
13	If necessary, repair or replace components. Is the renovation finished?	-	The system is normal	-
14	Check cylinder compression and valve synchronization. Check the camshaft for excessive wear. Malfunction detected?	-	Jump to operations 15	Jump to operations 16
15	If necessary, repair or replace engine components. Is the renovation finished?	-	The system is normal	-
16	Check the ECM ground connections to ensure they are clean, tight, and in the proper location. Check if the EGR valve is fully or partially open all the time? Check the operation of the torque converter clutch. Check the functioning of the air conditioning system. Check the generator output power. Repair the generator if the output power is outside the specified range. Are all checks and repairs complete?	12-16 V	The system is normal	-

Detonation/detonation when sparking

Step	Operation	Values	Yes	No
1	Have important preliminary checks been completed?	-	Jump to operations 2	Go to section "Important Preliminary Checks"
2	Fill the fuel tank with tested, high-quality gasoline with the octane rating specified. Evaluate the vehicle's performance again. Does the detonation problem persist?	Octane number 87-89	Jump to operations 3	The system is normal
3	Check for low engine coolant level. Check if there is any obstruction to the air flow to the radiator or restriction of the coolant flow. Check the thermostat for proper operation. Check the quality of the coolant solution. Malfunction detected?	-	Jump to operations 4	Jump to operations 5
4	If necessary, repair or replace components of the cooling system. Is the renovation finished?	-	The system is normal	-
5	Using a scan tool, check the engine coolant temperature. Replace the coolant temperature (ECT) sensor if the resistance is not within the limits specified in the Diagnostic Aid section for DTC P0118. Malfunction detected?	-	Jump to operations 6	Jump to operations 7
6	Replace the coolant temperature sensor or repair the circuit if necessary. Is the renovation finished?	-	The system is normal	-
7	Check the ignition output voltage using a spark tester. Check the heating zone and the gap of the spark plugs. Check the operation of the ignition control units. Is the ignition system working properly?	-	Jump to operations 9	Jump to operations 8
8	If necessary, repair or replace ignition system components. Is the renovation finished?	-	The system is normal	-
9	Connect the scanning tool to the diagnostic connector. Test drive the vehicle at a speed at which the malfunction occurs. Check the long term fuel trim readings using the scan tool data stream. Long Term Fuel Trim reading above set value?	20%	Go to section "Diagnostic information about trouble code P2177"	Jump to operations 10
10	Check the pressure in the fuel supply system. Malfunction detected?	410 kPa	Jump to operations 11	Jump to operations 12
11	If necessary, repair or replace fuel system components. Is the renovation finished?	-	The system is normal	-
12	Check if carbon deposits have formed inside the engine. Remove carbon deposits with a high-quality engine cleaner. Follow the instructions provided for that product. Check the main components - camshaft, cylinder head, pistons, etc. - for wear. Replace heavily worn parts. Is the procedure completed?	-	Jump to operations 13	-
13	Check the operation of the exhaust gas recirculation valve. Check the operation of the air intake system. Check the operation of the torque converter clutch and gearbox shift points. Check the service bulletins for updates to the Persistent Storage Device (PROM). Check the cylinder compression. Repair or replace all faulty components. Are all checks and repairs complete?	-	The system is normal	-

Delays, failures, jerks

Definition: Lack of immediate response when pressing the accelerator pedal. This can happen at any vehicle speed. It is usually most noticeable when attempting to move off. Sufficient delays, dips, or jerks can cause the engine to stall.

Important: Before diagnosing this condition, check for service bulletin updates for PROM.

Step	Operation	Values	Yes	No
1	Have important preliminary checks been completed?	-	Jump to operations 2	Go to section "Important Preliminary Checks"
2	Check the fuel system pressure. If the pressure is outside the specified value, service the fuel system as necessary. Check for a stuck or restricted throttle position sensor. The throttle position sensor signal should increase steadily as the throttle is moved to the fully open position. Malfunction detected?	410 kPa	Jump to operations 3	Jump to operations 4
3	If necessary, repair or replace components. Is the renovation finished?	-	The system is normal	-
4	Check the response and accuracy of the manifold absolute pressure sensor. Check fuel for water. Check the operation of the gasoline vapor recovery system (PVRS). Malfunction detected?	-	Jump to operations 5	Jump to operations 6
5	If necessary, repair or replace components. Is the renovation finished?	-	The system is normal	-
6	Disconnect the wiring harness connectors of all fuel injectors. Connect the injector test light between the harness terminals of each fuel injector. Pay attention to the indicator lamp when turning the crankshaft. Is the indicator light flashing on all connectors?	-	Jump to operations 8	Jump to operations 7
7	Repair or replace a faulty fuel injector drive harness, connector, or connector terminal. If the connections and wiring harness are OK, replace the ECM. Is the renovation finished?	-	The system is normal	-
8	Measure the resistance at each fuel injector. Fuel injector resistance within set value (the resistance will increase slightly at higher temperatures)?	11.6-12.4 Ohm	Jump to operations 10	Jump to operations 9
9	Replace the fuel injector with resistance that does not meet specifications. Is the renovation finished?	-	The system is normal	-
10	Conduct diagnostics of injectors. Malfunction detected?	-	Jump to operations 11	Jump to operations 12
11	Replace clogged or leaking fuel injectors. Is the renovation finished?	-	The system is normal	-
12	Check the fuel pressure after a cold start or during moderate to full throttle operation. Is the fuel pressure within specifications?	410 kPa	Jump to operations 14	Jump to operations 13
13	Remove obstruction in the fuel system or replace faulty fuel pump. Is the renovation finished?	-	The system is normal	-
14	Check the spark plugs for proper operation. Check the ignition output voltage at each cylinder using a spark tester. Malfunction detected?	-	Jump to operations 15	Jump to operations 16
15	If necessary, repair or replace ignition system components. Is the renovation finished?	-	The system is normal	-
16	Check the generator output voltage. Repair or replace the generator if the output power is less than the specified value Check the operation of the exhaust gas recirculation valve. Have all checks and necessary repairs been completed?	12-16 V	The system is normal	-

Engine misfires; Delays, failures

Definition: A constant pulsation or jerking sound that increases with engine load. Exhaust gases constantly hiss at idle or low speeds.

Step	Operation	Values	Yes	No
1	Have important preliminary checks been completed?	-	Jump to operations 2	Go to section "Important Preliminary Checks"
2	Check the ignition output voltage at each cylinder using a spark tester. Is there spark on all cylinders?	-	Jump to operations 3	Go to section "Checking the ignition system"
3	Check spark plugs for excessive wear, insulation breakdown, improper gap or heavy deposits. Malfunction detected?	-	Jump to operations 4	Jump to operations 5
4	If necessary, repair or replace components. Is the renovation finished?	-	The system is normal	-
5	Conduct a cylinder compression test. If compression is low, rebuild engine if necessary. Check for misaligned valve timing, bent valve lifters, worn rocker arms, broken or weakened valve springs and worn camshaft lobes. Check the intake manifold and exhaust manifold passages for burrs. Malfunction detected?	-	Jump to operations 6	Jump to operations 7
6	If necessary, repair or replace components. Is the renovation finished?	-	The system is normal	-
7	Check the fuel system for clogging of the built-in fuel filter. Check the fuel system for low fuel pressure. If the fuel pressure is below the specified value, service the fuel system as necessary. Check for fuel contamination. Malfunction detected?	410 kPa	Jump to operations 8	Jump to operations 9
8	If necessary, repair or replace components. Is the renovation finished?	-	The system is normal	-
9	Disconnect the wiring harness connectors from all fuel injectors. Connect the injector test light to the wire harness terminals of each fuel injector connector. Pay attention to the indicator lamp when turning the crankshaft on each fuel injector. Is the indicator light flashing on all fuel injectors?	-	Jump to operations 11	Jump to operations 10
10	Repair or replace a faulty injector drive chain harness, connector, or connector terminal. If the connections and wiring harness are OK, replace the ECM. Is the renovation finished?	-	The system is normal	-
11	Measure the resistance at each fuel injector. Injector resistance within the set value (the resistance will increase slightly at higher temperatures)?	11.6-12.4 Ohm	Jump to operations 13	Jump to operations 12
12	Replace fuel injectors with resistance that does not meet technical specifications. Is the renovation finished?	-	The system is normal	-
13	Conduct diagnostics of injectors. Malfunction detected?	-	Jump to operations 14	Jump to operations 15
14	Replace clogged or leaking fuel injectors. Is the renovation finished?	-	The system is normal	-
15	Check for electromagnetic interference. Check the engine speed using a scan tool. Does the RPM reading on the scan tool change greatly with only a small change in actual engine RPM?	-	Jump to operations 16	-
16	Check the ignition wire routing. Check all ignition system ground connections. Correct the gasket or repair ground connections as necessary. Have all checks and necessary repairs been completed?	-	The system is normal	-

High fuel consumption

Definition: Fuel economy measured during sea trials is significantly lower than expected. Also, fuel economy is significantly lower than measured during previous sea trials.

Important: Driving skills affect fuel economy. Ask the customer the following questions regarding driving skills:

1. Air conditioning system (for example, heating mode) always on?

2. Are the tires inflated to the correct pressure?

3. Is the vehicle used to transport heavy loads?

4. Is the driver accelerating too hard or too often? Recommend that the driver read the fuel economy section of the owner's manual.

Step	Operation	Values	Yes	No
1	Have important preliminary checks been completed?	-	Jump to operations 2	Go to section "Important Preliminary Checks"
2	Inspect the air filter for excessive contamination. Check the fuel system for leaks. Have all necessary checks been completed?	-	Jump to operations 3	-
3	Check spark plugs for excessive wear, insulation breakdown, improper gap or heavy deposits. Replace all faulty spark plugs. Have all necessary checks and repairs been completed?	-	Jump to operations 4	-
4	Check the coolant level. Check if the thermostat is constantly open and check the heating range. Replace thermostat if necessary. Have all necessary checks and repairs been completed?	-	Jump to operations 5	-
5	Check the gear shift pattern. Make sure all gears are working. Check the speedometer calibration. Check if the brakes are getting stuck. Check the cylinder compression. Repair, replace or adjust components as necessary. Have all checks and necessary repairs been completed?	-	The system is normal	-

Erratic operation or stalling at idle

Definition: The engine is idling rough. If this condition is severe, the vehicle may shake. The idle speed may also fluctuate (the engine "floats"). Either condition may be enough to stop the engine. The engine is idling incorrectly.

Important: Check for service bulletin updates before diagnosing.

Step	Operation	Values	Yes	No
1	Have important preliminary checks been completed?	-	Jump to operations 2	Go to section "Important Preliminary Checks"
2	Connect the scanning tool to the diagnostic connector. Check the oxygen sensor (O2S) readings at different throttle positions. Does the O2S sensor switch quickly from rich to lean at different throttle positions?	-	Jump to operations 5	Jump to operations 3
3	Check O2S sensor for fuel contamination or improper use of RTV sealant (room temperature vulcanizing sealant). Is the O2S sensor dirty?	-	Jump to operations 4	Jump to operations 5
4	If necessary, replace the contaminated O2S sensor. Is the renovation finished?	-	The system is normal	-
5	Check for a stuck throttle shaft or limiter linkage which may cause an incorrect throttle position sensor signal level. Check the signal level from the throttle position sensor with the throttle valve closed. Is the throttle position sensor signal level within the set value?	0.4-0.8 V	Jump to operations 6	Go to section "Diagnostic Trouble Code Information P0123"
6	Using a scanning device, check the coolant temperature sensor readings. Compare the coolant temperature sensor readings with the ambient temperature on a cold engine. Does the coolant temperature sensor reading differ from the ambient temperature by more than the specified value?	5°F (3°C)	Jump to operations 7	Jump to operations 9
7	Check for high resistance in the coolant temperature sensor circuit or in the sensor itself. Malfunction detected?	-	Jump to operations 8	Jump to operations 9
8	Replace the coolant temperature sensor or repair the circuit if necessary. Is the renovation finished?	-	The system is normal	-
9	Check the response and accuracy of the manifold absolute pressure sensor. Malfunction detected?	-	Jump to operations 10	Jump to operations 11
10	Replace the manifold absolute pressure sensor or repair the sensor circuit as necessary. Is the renovation finished?	-	The system is normal	-
11	Test drive the vehicle at a speed at which the malfunction occurs. Check the long term fuel trim readings with a scan tool. Is the long term fuel trim reading within the set value?	-20-20%	Jump to operations 14	Jump to operations 12
12	Long Term Fuel Trim reading below set value?	-20%	Go to section "Diagnostic information about trouble code P2178"	Jump to operations 13
13	Long Term Fuel Trim reading above set value?	20%	Go to section "Diagnostic information about trouble code P2177"	-
14	Disconnect the wiring harness connectors from all fuel injectors. Connect the injector test light between the harness terminals of each fuel injector connector. Pay attention to the indicator lamp when turning the crankshaft. Is the indicator light flashing on all fuel injectors?	-	Jump to operations 16	Jump to operations 15
15	Replace a faulty fuel injector drive harness, connector, or connector terminal. If the wiring harness, connectors and terminals are normal, replace the ECM. Is the renovation finished?	-	The system is normal	-
16	Measure the resistance of each fuel injector. Resistance within the set value (the resistance will increase slightly at higher temperatures)?	11.6-12.4 Ohm	Jump to operations 18	Jump to operations 17
17	Replace fuel injectors with resistance that does not meet technical specifications. Is the renovation finished?	-	The system is normal	-
18	Conduct diagnostics of injectors. Malfunction detected?	-	Jump to operations 19	Jump to operations 20
19	Replace clogged or leaking fuel injectors as necessary. Is the renovation finished?	-	The system is normal	-
20	With the engine off, disconnect the fuel pressure regulator vacuum hose. Carefully inspect the fuel pressure regulator vacuum fitting and fuel pressure regulator vacuum hose for fuel. Malfunction detected?	-	Jump to operations 21	Jump to operations 22
21	Replace the fuel pressure regulator if necessary. Is the renovation finished?	-	The system is normal	-
22	Check the ignition output voltage at each cylinder using a spark tester. Check spark plugs for excessive wear, insulation breakdown, improper gap or heavy deposits. Check the ignition wires for kinks, stiffness and correct connection. Malfunction detected?	-	Jump to operations 23	Jump to operations 24
23	Repair or replace ignition system components as necessary. Is the renovation finished?	-	The system is normal	-
24	Check for leaks in vacuum lines. Check the operation of the forced crankcase ventilation. Check the operation of the idle air control valve. Check all ECM ground connections. Malfunction detected?	-	Jump to operations 25	Jump to operations 26
25	If necessary, repair or replace components. Is the renovation finished?	-	The system is normal	-
26	Check the operation of the exhaust gas recirculation valve. Check the battery wires and body mounting strips for secure connections. Check the generator output voltage. Repair or replace the generator if the output voltage is out of the specified value? Malfunction detected?	12-16 V	Jump to operations 27	Jump to operations 28
27	If necessary, repair or replace components. Is the renovation finished?	-	The system is normal	-
28	Check the serviceability of the engine mounts. Check valve synchronization. Conduct a cylinder compression test. Check for bent valve lifters, worn rocker arms, broken or weakened valve springs, and a worn camshaft. Perform repairs if necessary. Have all checks and necessary repairs been completed?	-	The system is normal	-

Increased toxicity or unpleasant odor of exhaust gases

Definition: The vehicle fails an emissions test. The vehicle has a strong rotten egg odor. Excessive odor does not necessarily mean excessive toxicity.

Step	Operation	Values	Yes	No
1	Have important preliminary checks been completed?	-	Jump to operations 2	Go to section "Important Preliminary Checks"
2	Start the engine and allow it to warm up to operating temperature. Perform an exhaust gas toxicity test. Has the car passed a toxicity test?	-	The system is normal	Jump to operations 3
3	Connect the scanning tool to the diagnostic connector. Perform a test drive. Check the long-term fuel trim memory. Long-term fuel trim memory within the set value?	-20-20%	Jump to operations 6	Jump to operations 4
4	Long Term Fuel Trim Memory Below Set Value?	-20%	Go to section "Diagnostic information about trouble code P2178"	Jump to operations 5
5	Long Term Fuel Trim reading above set value?	20%	Go to section "Diagnostic information about trouble code P2177"	-
6	Check that the fuel tank cap is installed correctly. Check the pressure in the fuel supply system. Conduct diagnostics of injectors. Malfunction detected?	-	Jump to operations 7	Jump to operations 8
7	Repair or replace fuel system components as necessary. Perform an exhaust gas toxicity test. Has the car passed a toxicity test?	-	The system is normal	-
8	Check the operation of the ignition system. Check spark plugs for excessive wear, insulation breakdown, improper gap or heavy deposits. Malfunction detected?	-	Jump to operations 9	Jump to operations 10
9	Repair or replace ignition system components as necessary. Perform an exhaust gas toxicity test. Has the car passed a toxicity test?	-	The system is normal	-
10	Check for leaks in vacuum lines. Check the catalytic converter for contamination. Check for carbon deposits on the throttle body and in the throttle valve, as well as inside the engine. Remove the upper engine cleaner. Check if the exhaust gas recirculation valve opens. Check the operation of the forced crankcase ventilation. Have all checks and necessary repairs been completed?	-	The system is normal	-

Compression ignition

Definition: The engine continues to run after the ignition is turned off.

Step	Operation	Values	Yes	No
1	Have important preliminary checks been completed?	-	Jump to operations 2	Go to section "Important Preliminary Checks"
2	Does the engine run smoothly after the ignition is turned off?	-	Jump to operations 3	Jump to operations 4
3	Check the ignition switch and its adjustment. Replace ignition switch if necessary. Is the renovation finished?	-	The system is normal	-
4	Check the gasoline vapor recovery system. Check for fuel injector leaks. Check the operation of the idle air control valve. Check for leaks in vacuum lines. Check the basic idle settings. Are all checks and repairs complete?	-	The system is normal	-

Backfire

Definition: Fuel ignites in the intake manifold or exhaust system, producing a popping sound.

Important: Check for service bulletin updates before diagnosing.

Step	Operation	Values	Yes	No
1	Have important preliminary checks been completed?	-	Jump to operations 2	Go to section "Important Preliminary Checks"
2	Check the spark plugs for sparks due to mutual influence. Check the ignition output voltage at each cylinder using a spark tester. Check spark plugs for excessive wear, improper gap, burnt electrodes or heavy deposits. Malfunction detected?	-	Jump to operations 3	Jump to operations 4
3	Repair or replace ignition system components as necessary. Is the renovation finished?	-	The system is normal	-
4	Check the operation of the fuel system. Conduct diagnostics of fuel injector operation. Malfunction detected?	-	Jump to operations 5	Jump to operations 6
5	Repair or replace fuel system components as necessary. Is the renovation finished?	-	The system is normal	-
6	Check the EGR gasket for leaks or looseness. Check the operation of the exhaust gas recirculation valve. Check the intake manifold and exhaust manifold for burrs. Malfunction detected?	-	Jump to operations 7	Jump to operations 8
7	If necessary, repair or replace components. Is the renovation finished?	-	The system is normal	-
8	Check engine compression. Check the intake manifold and exhaust manifold for leaks. Check for valve sticking and leakage. If necessary, repair or replace components. Are all checks and repairs complete?	-	The system is normal	-