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Home >> Audi >> 1984 >> 5000 4D Sedan, 2.2 C >> Repair and Diagnosis >> Engine Performance >> System >> Fuel Injection System - BOSCH Cis-E (Turbo) >> Testing >> Fuel System >> MCU Check for Constant Delivery

MCU Check for Constant Delivery

  1. The measuring procedure is basically the same as that done on Mercedes-Benz with CIS-E. Using Analyzer (US 4480) and fuel pump relay Jumper (US 4480/3), injection quantities are compared for a given sensor plate position.
  2. Injectors are removed from engine with lines attached. After checking seals for damage or looseness and checking injectors for tightness of inserts, injectors are plugged into analyzer. If injector inserts are loose, remove and clean threads. Reinstall with Loctite 620 and tighten to 16 ft. lbs. (22 N.m).
  3. Turn and lift screw and adjusting slide into upper (full throttle) position on sensor plate lift Adjusting Tool (VW 1348/1). Place adjusting tool on center of air flow sensor assembly with pointer facing center of fuel distributor. Push adjusting slide down onto stop.
  4. Turn setting screw clockwise until magnetic end touches air flow sensor plate retaining bolt. Switch on Jumper (US 4480/3) and turn adjusting screw counterclockwise until fuel injection begins at one injector. Switch off jumper and empty fuel from analyzer into tank.
  5. To measure idle injection quantity, lift adjusting slide to first stop to simulate idle. Switch on jumper until fuel level reaches 20 ml in any measuring tube. Injector spray pattern must be even and conical. All injector spray patterns should look the same. If spray patterns vary or are incorrect, lift sensor plate to full travel and repeat test.
  6. Keeping analyzer tubes vertical, compare fuel quantity in all tubes. Maximum difference between tubes may not be more than 3.0 ml. If level differs more than 3.0 ml between any 2 tubes, interchange injectors and repeat test. If fuel quantity difference remains the same, either a fuel line or the fuel distributor is at fault.
  7. If fuel quantity difference changes with the change of injectors, replace the injectors. Empty measuring device and reinstall injectors into analyzer. Lift adjusting slide to last stop to simulate full throttle. Switch on fuel pump jumper until fuel level reaches 80 ml in any one measuring tube.
  8. Note injector patterns, which should be even, conical, and similar to one another. If not, lift sensor plate fully and repeat test. Compare amounts of fuel in measuring tubes. Maximum difference between any two injectors is 8.0 ml of fuel. Repeat interchange of injectors in fuel quantity variation exceeds standard. Apply same criteria to results of this test as in step 6).
  9. After measuring is finished, immediately test injectors for seepage or leaks. Set sensor plate in rest position. Switch on jumper for 2 minutes. Injectors must not drip fuel during this test.
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