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4.16. Functioning check, removal and installation of the measuring instrument of a stream of air

Check (L-Jetronic systems)

 PERFORMANCE ORDER

  1. Disconnect from the entrance union of the measuring instrument of a stream of air. Carefully open and close the gate of the sensor and check jamming existence. The gate at backfires can be bent and it to lead to the wrong measurements of resistance. The gate can be bent and remain in partially open situation, causing enrichment of mix and a stop of the engine idling.
  1. Disconnect the electric socket from the air stream measuring instrument.
  1. Check an ohmmeter resistance between contacts 7 and 8. Resistance has to increase constantly (without "flat sites") at slow movement of the gate of the sensor from completely closed position in completely open.
  1. Also check the sensor of temperature of inlet air (in the stream measuring instrument). Check an ohmmeter correctness of resistance between contacts 8 and 9 (see an illustration above). Resistance at 20 °C has to make size from 2200 to 2700 Ohms.
  1. If resistance sizes correct, check cables (watch the Head Sistem of onboard electric equipment). Attach the socket to the stream measuring instrument. Make sure that ignition is switched off. Disconnect the socket from ECU (it is located under the dashboard on the right) and check an ohmmeter resistance between contact 7 and 8. Carefully uncover with the measuring instrument a stream and observe change of resistance when moving from a closed position to completely open. The result of check has to be same, as at the previous check. If in results any differences are observed, then in a cable there can be breaks or short circuits.

Check of functioning (Motronic system)

 PERFORMANCE ORDER

  1. Make sure that ignition is switched off. Uncover access to ECU (watch Chapter of the Control system of the engine and decrease in toxicity of the fulfilled gases) and disconnect the cable socket.
  1. Check an ohmmeter resistance between noted contacts of the electric ECU socket and check change of resistance when moving a petal. On the early Motronic systems use contacts 7 and 9.
  1. On late models - contacts 7 and 12.
  1. Resistance has to increase continuously (without "flat sites") when moving a petal of the sensor from completely closed position in completely open.

The early Motronic systems differ in the 35-contact electric socket; in the late Motronic systems the 55-contact socket is used.

  1. If resistance size wrong, check a cable.

Removal and installation (all systems)

 PERFORMANCE ORDER

  1. Disconnect the electric socket from the stream measuring instrument.
  2. Remove the air cleaner (look the Section Removal and installation of the air cleaner).
  1. Turn off nuts and take the stream measuring instrument from a motive compartment or from the air cleaner.
 
  1. Installation back to removal.