Chrysler Colt/Vista 1990-1993 Repair Information

Fuel Injectors

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REMOVAL & INSTALLATION




WARNING
The injectors are extremely sensitive to dirt and impact. They must be handled gently and protected at all times. The entire work area must be as clean as possible. Any particle of dirt entering the system can foul an injector or change its operation. Any gaskets or O-rings removed with the injector MUST be replaced with new ones at reassembly. Do not attempt to reuse these seals; high pressure fuel leaks may result.

Except 1.6L Engines

See Figures 1 and 2



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Fig. Fig. 1: Fuel injectors and related parts - 1990-93 1.5L, 1990 1.8L and 1992-93 1.8L engines



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Fig. Fig. 2: Fuel injectors and related parts - 2.0L and 2.4L engines

  1. Safely relieve the pressure within the fuel system.
  2.  


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the high pressure fuel line at the delivery pipe (rail). The O-ring inside the fitting is not reusable.
  4.  


WARNING
Wrap the connection in a clean towel or cloth before disconnecting. Some pressure will remain within the system.

  1. Disconnect the fuel return hose and remove its O-ring.
  2.  
  3. Disconnect the electrical connector to each injector. Label each at the time of removal.
  4.  
  5. Remove the bolts holding the injector rail; remove the rubber grommets or insulators below the rail mounting points.
  6.  
  7. Lift the rail with the injectors attached up and away from the engine. Take great care not to drop any of the injectors during this removal.
  8.  


WARNING
If an injector should fall and hit the floor or other hard surface, it must be considered unusable.

  1. The injectors may be removed from the rail with a gentle pull. Both the grommet and O-ring on the top of the injector must be discarded and replaced. The lower insulator or seat must also be removed and replaced.
  2.  
  3. Reassembly begins by installing a new grommet and O-ring (in that order) onto the injector. Coat the O-ring with a light coating of gasoline. Do not use grease or oil.
  4.  
  5. Install each injector into the rail, making sure that the injector turns freely when in place. If it does not turn under finger pressure, remove it, inspect the O-ring and reinsert the injector. (While the injector does not turn during its operation, its ability to turn is an indicator of correct installation).
  6.  
  7. Replace the seats in the intake manifold. Install the delivery pipe and the injectors onto the manifold without dropping an injector. Make certain the rubber bushings are in place under the delivery pipe brackets.
  8.  
  9. Tighten the fuel rail bolts to 11 Nm (8 ft. lbs or 72 INCH lbs.).
  10.  
  11. Connect each electrical connector to the proper injector.
  12.  
  13. Replace the O-ring, coat it lightly with gasoline and connect the fuel pressure regulator. Tighten the connection to 8 Nm (6 ft. lbs or 72 INCH lbs.).
  14.  
  15. Connect the fuel return hose.
  16.  
  17. Replace the O-ring, coat it lightly with gasoline and install the high pressure fuel line. Make certain the O-ring is not damaged during installation. Tighten the bolts to 4 Nm (3 ft. lbs. or 36 INCH lbs.).
  18.  
  19. Connect the negative battery cable.
  20.  

1.6L Engines

See Figure 3



Click image to see an enlarged view

Fig. Fig. 3: Fuel injectors and related parts - 1.6L engines

  1. Safely relieve the pressure within the fuel system.
  2.  


CAUTION
The fuel system is under pressure. Release pressure slowly and contain spillage. Observe no smoking/no open flame precautions. Have a Class B-C (dry powder) fire extinguisher within arm's reach at all times.

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the high pressure fuel line at the delivery pipe (rail). The O-ring inside the fitting is not reusable.
  4.  


WARNING
Wrap the connection in a clean towel or cloth before disconnecting. Some pressure will remain within the system.

  1. Disconnect the fuel return hose and remove its O-ring. Disconnect the vacuum hose from the fuel pressure regulator.
  2.  
  3. Remove the fuel pressure regulator and its O-ring.
  4.  
  5. Disconnect the PCV hose.
  6.  
  7. Remove the electrical connector from each injector.
  8.  
  9. Remove the bolts holding the delivery pipe to the engine. Note that the accelerator cable retaining brackets will come off.
  10.  
  11. Lift the rail with the injectors attached up and away from the engine. Take great care not to drop any of the injectors during this removal.
  12.  


WARNING
If an injector should fall and hit the floor or other hard surface, it must be considered unusable.

  1. The injectors may be removed from the rail with a gentle pull. Both the grommet and O-ring on the top of the injector must be discarded and replaced. The lower insulator or seat must also be removed and replaced.
  2.  
  3. Reassembly begins by installing a new grommet and O-ring (in that order) onto the injector. Coat the O-ring with a light coating of gasoline. Do not use grease or oil.
  4.  
  5. Install each injector into the rail, making sure that the injector turns freely when in place. If it does not turn under finger pressure, remove it, inspect the O-ring and reinsert the injector. (While the injector does not turn during its operation, its ability to turn is an indicator of correct installation).
  6.  
  7. Replace the seats in the intake manifold. Install the delivery pipe and the injectors onto the manifold without dropping an injector. Make certain the rubber bushings are in place under the delivery pipe brackets.
  8.  
  9. Tighten the fuel rail bolts to 11 Nm (8 ft. lbs or 72 INCH lbs.) Remember to include the accelerator cable brackets under the bolt.
  10.  
  11. Connect each electrical connector to the proper injector.
  12.  
  13. Connect the PCV hose.
  14.  
  15. Replace the O-ring, coat it lightly with gasoline and install the fuel pressure regulator. Tighten the fasteners to 8 Nm (6 ft. lbs or 72 INCH lbs.).
  16.  
  17. Connect the fuel return hose.
  18.  
  19. Replace the O-ring, coat it lightly with gasoline and install the high pressure fuel line. Make certain the O-ring is not damaged during installation. Tighten the bolts to 4 Nm (36 INCH lbs.).
  20.  
  21. Connect the negative battery cable.
  22.  

FUEL INJECTOR TESTING



See Figure 4

The simplest way to test the injectors is simply to listen to them with the engine running. Use a mechanic's stethoscope, touch each injector while the engine is idling. You should hear a distinct clicking as each injector opens and closes. Check that the operating sound increases as the engine speed is increased.

The sounds of the other injector(s) may be heard, even though the one being checked is not operating. Listen to each injector to get a feel for normal sounds; the one with the abnormal sound is the problem.



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Fig. Fig. 4: Checking injector resistance

Additionally, the resistance of the injector can be easily checked. Disconnect the negative battery cable and remove the electrical connector from the injector to be tested. Use an ohmmeter to check the resistance across the terminals of the injector. Correct resistance at 68°F (20°C) is 13-16-.

Slight variations are acceptable due to temperature conditions.

Bench testing of the injectors can only be done using expensive special equipment. Generally this equipment can be found at a dealership and sometimes at a well-equipped machine shop or performance shop. There is no provision for field testing the injectors by the owner/mechanic. DO NOT attempt to test the injector by removing it from the engine and making it spray into a jar.

Never attempt to check a removed injector by hooking it directly to the battery. The injector runs on a much smaller voltage and the 12 volts from the battery will destroy it internally. Since this happens at the speed of electricity, you don't get a second chance.

TESTING THE INJECTION SYSTEM AND SENSORS



For complete fuel injection testing, see the Engine Controls information .

As stated before, the heart of any fuel injection system is the computer or ECU. Besides reacting to the changing signals from various sensors and controlling various relays, switches and injectors, the ECU can serve an important diagnostic function. It "knows" what characteristics to look for in the signal from each unit. If any irregularity is detected (improper voltage, improper time duration, etc) the ECU notes the problem and assigns it a predetermined identifying number. if two of more faults are sensed, the codes are stored in numeric order. In some cases a light on the dashboard will come on to show a fault has occurred. Even without a dash light, the fault code is stored in the computer until someone asks for it.

If you're going to read these codes, certain conditions must be observed. Since the codes are maintained by battery voltage, the battery must be fully charged. If the battery is low on charge, the codes may be lost. The codes will be lost (erased) if the battery cable is disconnected or if the ECU is disconnected before the codes are read. Additionally, the engine should be fully warmed up and driven a good distance before retrieving the codes; this allows the sensors and the oxygen sensor to enter their proper ranges.

Mitsubishi, like most manufacturers, has a diagnostic tool which plugs into the system between the wire harness and the ECU. This tester allows the operator to read out trouble codes and check the operation of various components during operation. Think of the tester as a window through which you can see the voltages change as they are transmitted to or from the ECU. If the normal values are known, a faulty item can be quickly found.

Unfortunately, these diagnostic tools are extremely expensive. The cost far exceeds the need of the owner/mechanic who is occasionally servicing one or two cars. If you suspect a fuel injection system problem that cannot be found through more common diagnostic means, take the car to either a dealer or a reputable diagnostic shop. The cost will be well repaid by the speed of diagnosis.

The stored codes may also be read on an analog (dial type) voltmeter hooked into the system. Since the output from the ECU is electrical, the meter needle will deflect or sweep as the pulses are generated. Recording the number of sweeps and their time duration will yield the numeric code involved. (For example: Two 1 / 2 -second sweeps followed by a 2 second pause followed by three 1 / 2 -sweeps might indicate code 23 or code 2 and code 3, depending on the system.).


WARNING
The order of the fault codes does NOT indicate the order of occurrence. Multiple codes are stored in numerical order, regardless of which occurred first.

The code, when interpreted, points you to the unit which may be the problem. It must still be checked along with the attendant wiring, connectors and controls. A great number of fault codes are set because of loose or dirty connections in the wiring which fool the ECU into thinking the unit has failed.

The following information gives the diagnosis codes for each fuel injected engine, where to hook up the voltmeter and volt or ohmmeter testing for certain components. Note that not every component can be tested with a meter. Additional testing information for some components may also be found in Emission Controls in this information. In each case remember that you are only reading voltage used to transmit a code; the actual voltage running within the system can only be checked with the factory diagnostic unit.

All resistances given are for 68°F (20°C). Remember that resistance will increase or decrease respectively as the temperature rises or falls. Use common sense in interpreting readings.

1.5L, 1.6L, and 1990 1.8L Engines

Because the MPI injection system requires more sensors to operate properly, the ECU can store and report more codes. The codes are identified by two digit numbers. With the engine off, connect the voltmeter (set to read 12v DC) to the diagnostic connector under the dash. Turn the ignition switch to ON ; the codes will begin transmitting immediately.

If all is well and no codes are stored, the ECU broadcasts a steady stream of 1 / 2 -second pulses with one half second between each. If the ECU has failed (or diagnosed itself as having a problem) the system will transmit an unchanging 12 volt signal. When a two digit code is sent, the first (or tens) digit is sent in longer 1 1 / 2 second pulses; the second digit is sent in 1 / 2 -second pulses. Two long sweeps and three short duration sweeps of the meter needle would indicate code 23. If more than one code is stored, the first digit of the second code will be sent after a three second pause. The entire sequence of codes will be retransmitted repeatedly; if you don't get all of it the first time, wait until it repeats.

Note that each engine has its own family of codes. Some are the same but there are differences. Make certain the correct chart is in use when performing diagnostic work.

TESTING THE INTAKE AIR TEMPERATURE SENSOR

See Figures 5, 6, 7, 8, 9 and 10

  1. Disconnect the air flow sensor connector.
  2.  



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Fig. Fig. 5: Diagnostic connector voltmeter hookup - 1.5L, 1.6L and 1990 1.8L engines



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Fig. Fig. 6: Pulse duration indicates place value for each 2-digit code



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Fig. Fig. 7: Trouble codes for 1.5L, and 1990 1.8L engines

  1. Connect the terminals of the ohmmeter between terminal Nos. 4 and 6 on the 4G15 or Nos. 6 and 8 on the 4G61. Resistance will depend on air temperature. Two reference points are: 32°F (0°C), 6k- and 68°F (20°C), 2.7k-.
  2.  



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Fig. Fig. 8: Trouble codes for 1.6L engines



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Fig. Fig. 9: Checking the air temperature sensor - 1.5L and 1990 1.8L engines



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Fig. Fig. 10: Checking the air temperature sensor - 1.6L engines

  1. Use a hand-held hair dryer to blow warm air over the sensor. The resistance should change with the temperature increase.
  2.  
  3. If the values are not close to target or do not change with temperature, the unit is faulty and must be replaced.
  4.  
  5. Remove the test equipment and reconnect the wire harness.
  6.  

TESTING THE THROTTLE POSITION SENSOR

See Figures 11 and 12


WARNING
The use of the correct special tools or their equivalent is REQUIRED for this procedure. Wiring harness adapter MD 998478 (998464 for 1.6L) is highly recommended to prevent damage to the wiring and connectors.

  1. With the engine off, disconnect the TPS wiring connector.
  2.  



Click image to see an enlarged view

Fig. Fig. 11: Checking the throttle position sensor - 1.5L and 1990 1.8L engines



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Fig. Fig. 12: Checking the throttle position sensor - 1.6L engines

  1. Install the special wiring device between the connectors.
  2.  
  3. On all except the 1.6L, connect the ohmmeter across terminal Nos. 1 (ground; the black clip on the adapter) and 2 (the red clip on the adapter). On the 1.6L, connect the ohmmeter to terminal No. 2 (red clip) and 3 (white clip). In both cases, the resistance should be 3.5-6.5 -.
  4.  
  5. Move the positive ohmmeter lead to terminal No.3 (blue clip) on all except the 1.6L; connector or No.4 (blue clip) on the 1.6L. Operate the throttle slowly and smoothly from idle to wide open; the resistance shown on the meter should change smoothly and in proportion to the throttle motion. Even though the resistance may be correct, if it does not change smoothly with throttle motion, the unit is defective and must be replaced.
  6.  
  7. Remove the test equipment and connect the wiring harness.
  8.  

RESETTING THE SYSTEM

After recording the fault code and making repairs based on diagnosis, disconnect the negative battery cable for at least 15 seconds. Reconnect the cable and check for fault codes after running the engine. If the repair cured the problem, the original fault code should not reappear. The fault code will remain stored (even after repair) if the battery cable is not disconnected.

1992-93 1.8L and 2.4L Engines

With the ignition switch off, open the glovebox and pull out the diagnostic connector located behind the glovebox. It may be easier to remove the glovebox completely; the diagnostic connector is not on a very long harness. Connect the voltmeter (set to read 12v DC) to the diagnostic connector, observing the correct polarity. The codes will be transmitted when the ignition is turned ON .

The codes will be transmitted as a series of long and short duration pulses which you will see as needle motion on the meter. A short pulse translates as a zero and a long pulse as a one. These binary codes are are 5 digits long and all must be read before knowing the code. An example would be: short-short-long-short-short or 00100. This is not code 100; it is the designation-in binary code-for trouble code 4 or the atmospheric pressure sensor. Record the flashes carefully and use the chart to understand them.

TESTING THE INTAKE AIR TEMPERATURE SENSOR

See Figures 13 and 14



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Fig. Fig. 13: Diagnostic connector voltmeter hookup - 1992-93 1.8L and 2.4L engines



Click image to see an enlarged view

Fig. Fig. 14: Checking the air temperature sensor - 1992-93 1.8L and 2.4L engines

  1. Disconnect the air flow sensor connector.
  2.  
  3. Connect the terminals of the ohmmeter between terminal Nos. 2 and 4. Resistance will depend on air temperature. Two reference points are: 32°F (0°C), 6- and 68°F (20°C), 2.7-.
  4.  
  5. Use a hand-held hair dryer to blow warm air over the sensor. The resistance should change with the temperature increase.
  6.  
  7. If the values are not close to target or do not change with temperature, the unit is faulty and must be replaced.
  8.  
  9. Remove the test equipment and reconnect the wire harness.
  10.  

TESTING THE THROTTLE POSITION SENSOR

See Figures 15 and 16



Click image to see an enlarged view

Fig. Fig. 15: The binary codes are not difficult but may be confusing. Record the needle sweeps carefully



Click image to see an enlarged view

Fig. Fig. 16: Checking the throttle position sensor - 1992-93 1.8L and 2.4L engines

  1. With the engine off, disconnect the TPS wiring connector.
  2.  
  3. Connect the ohmmeter across terminal Nos. 1 (ground) and 3. The resistance should be 3.5-6.5 k-.
  4.  
  5. Move the positive ohmmeter lead to terminal No.2 on the connector. Operate the throttle slowly and smoothly from idle to wide open; the resistance shown on the meter should change smoothly and in proportion to the throttle motion.
  6.  
  7. Even though the resistance may be correct, if it does not change smoothly with throttle motion, the unit is defective and must be replaced.
  8.  
  9. Remove the test equipment and connect the wiring harness.
  10.  

RESETTING THE SYSTEM

After recording the fault code and making repairs based on diagnosis, disconnect the negative battery cable for at least 15 seconds. Reconnect the cable and check for fault codes after running the engine. If the repair cured the problem, the original fault code should not reappear. The fault code will remain stored (even after repair) if the battery cable is not disconnected.

2.0L Engines

This engine incorporates several additional sensors to improve engine control and driveability. The ECU can store and report more codes. The codes are identified by two digit numbers. With the engine off, connect the voltmeter (set to read 12v DC) to the diagnostic connector under the dash. Turn the ignition switch to ON ; the codes will begin transmitting immediately.

If all is well and no codes are stored, the ECU broadcasts a steady stream of 1 / 2 -second pulses with one half second between each. If the ECU has failed (or diagnosed itself as having a problem) the system will transmit an unchanging 12 volt signal. When a two digit fault code is sent, the first (or tens) digit is sent in longer 1 1 / 2 second pulses; the second digit is sent in 1 / 2 -second pulses. Two long sweeps and three short-duration sweeps of the meter needle would indicate code 23. If more than one code is stored, the first digit of the second code will be sent after a three second pause. The entire sequence of codes will be retransmitted repeatedly; if you don't get all of it the first time, wait until it repeats.

Note that each engine has its own family of codes. Some are the same but there are differences. Make certain the correct chart is in use when performing diagnostic work.

TESTING THE INTAKE AIR TEMPERATURE SENSOR

See Figure 17



Click image to see an enlarged view

Fig. Fig. 17: Checking the air temperature sensor - 2.0L engines

  1. Disconnect the air flow sensor connector.
  2.  
  3. Connect the terminals of the ohmmeter between terminal Nos. 4 and 6 on either engine. Resistance will depend on air temperature. Two reference points are: 32°F (0°C), 6- and 68°F (20°C), 2.7-.
  4.  
  5. Use a hand-held hair dryer to blow warm air over the sensor. The resistance should change with the temperature increase.
  6.  
  7. If the values are not close to target or do not change with temperature, the unit is faulty and must be replaced.
  8.  
  9. Remove the test equipment and reconnect the wire harness.
  10.  

TESTING THE THROTTLE POSITION SENSOR

See Figures 18 and 19



Click image to see an enlarged view

Fig. Fig. 18: TPS sensor location - 2.0L engines



Click image to see an enlarged view

Fig. Fig. 19: Checking the throttle position sensor - 2.0L engines


WARNING
The use of the correct special tools or their equivalent is REQUIRED for this procedure. Wiring harness adapter MD 998478 for the SOHC or 998464 for the DOHC is highly recommended to prevent damage to the wiring and connectors.

  1. With the engine off, disconnect the TPS wiring connector.
  2.  
  3. Install the special wiring device between the connectors.
  4.  
  5. On the SOHC, connect the ohmmeter across terminal Nos. 1 (ground; the black clip on the adapter) and 2 (the red clip on the adapter). On the DOHC, connect the ohmmeter to terminal No. 2 (red clip) and 3 (white clip). In both cases, the resistance should be 3.5-6.5 -.
  6.  
  7. Move the positive ohmmeter lead to terminal No.3 (blue clip) on the SOHC connector or No.4 (blue clip) on the DOHC. Operate the throttle slowly and smoothly from idle to wide open; the resistance shown on the meter should change smoothly and in proportion to the throttle motion.
  8.  
  9. Even though the resistance may be correct, if it does not change smoothly with throttle motion, the unit is defective and must be replaced.
  10.  
  11. Remove the test equipment and connect the wiring harness.
  12.  

RESETTING THE SYSTEM

See Figures 20 and 21



Click image to see an enlarged view

Fig. Fig. 20: Pulse duration indicates place value for each 2-digit code



Click image to see an enlarged view

Fig. Fig. 21: Trouble codes for 2.0L engines

After recording the fault code and making repairs based on diagnosis, disconnect the negative battery cable for at least 15 seconds. Reconnect the cable and check for fault codes after running the engine. If the repair cured the problem, the original fault code should not reappear. The fault code will remain stored (even after repair) if the battery cable is not disconnected.

 
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