Metal Tipped Fuel Injectors - Checking/Cleaning
91audi04
Group: 25
Number: 91-05
Date: June 30, 1991
Subject: Metal Tipped Fuel Injectors, Checking/Cleaning
Model(s): All with CIS, CIS-E, CIS-E III m.y. 1985-1991
Applies to the following Audi models:
All 4000 1985-1987
All 5000 1985-1987
100 1989-1991
200 1989-1991
80/90 1988-1991
^ check part number stamped on barrel of injector
Note
Two types of fuel injectors are used in these vehicles; Viton tipped, and metal tipped (non-Viton). Viton tipped injectors will have one of the following Bosch part numbers stamped on the body of the injector:
0-437-502-043 High pressure concept, fine
thread (replacement)
(Audi Replacement, Part Number: 035 133 551F)
0-437-502-044 High pressure concept, fine
thread (OEM)
(Audi Replacement, Part Number: 035 133 551F)
0-437-502-045 Low pressure, coarse thread
(replacement)
(Audi Replacement, Part Number: 026 133 551)
0-437-502-046 Low pressure, coarse thread
(OEM)
(Audi Replacement, Part Number: 026 133 551)
If one of the above Part Numbers is found
^ refer to Technical Bulletin, Repair Group 25, 91-04 "Viton Tipped Injectors, Cleaning and Checking"
Any other part number indicates that it is metal tipped.
Notes regarding metal tipped injectors:
Metal tipped injectors are no longer available as spare parts, replacements will be Viton tipped
CAUTION
Part numbers are for reference only. Always consult with the Parts Department for the latest information.
^ If one or more metal tipped injectors has to be replaced the entire set must be replaced
^ Viton and metal tipped injectors must not be used together
Metal tipped fuel injectors, cleaning/ checking
Note
Poor injector performance can often be corrected by flushing and testing the injector using the US 8034 injector tester.
CAUTION
Perform the following checks in sequence.
Corrosion checking
^ visually inspect tip of injector for rust
If YES
^ replace injector
If NO
^ proceed with following procedures
WARNING
Fluid used in tester (Shell mineral spirits 135) is flammable. Do not smoke or have anything in area that can ignite fuel.
Contamination and varnish, checking
^ open US 8034 pressure valve fully by turning counterclockwise
^ loosely connect injector to tester via union nut
^ bleed air from pressure line by operating lever several times, allowing tester fluid to escape through nut
^ use a suitable container under injector to catch overspray
^ tighten union nut
^ slowly operate hand lever
^ approx. 2 strokes per second
^ if pressure does not build up, injector has leakage (e.g. foreign object(s) lodged between seat). If this is the case, proceed to bleeding of injector and repeat contamination test
^ if after bleeding, pressure is restored; return to this point and continue with sequence
^ observe pressure on gauge
^ minimum opening pressure must be 1.5 to 2.0 bar
If NO
^ injector may be contaminated or varnished
^ close valve on US 8034
^ flush injector by operating tester with 20 to 30 vigorous strokes
^ repeat contamination check
If still below specification
^ replace injector
If OK
^ bleed injector by rapidly operating tester 20 to 30 strokes
^ injector is bled when sound of escaping fluid stabilizes
Opening pressure, checking
^ open valve on US 8034
^ slowly operate hand lever 9
^ approx. 2 strokes per second
^ observe pressure on gauge
^ opening pressure must be 3.0 to 4.1 bar (low pressure), 4.3 to 4.6 bar (high pressure concept)
Leak checking
Requirement
^ Hand valve on US 8034 must be open
^ using the previously established opening pressure as a reference; slowly increase the pressure to 0.5 bar below that value
For example: If opening pressure was 4.0 bar; the leak checking pressure must be 3.5 bar
^ a droplet may form at the tip of the injector within 15 seconds, however; if the droplet falls off the injector must be replaced
Chatter, spray pattern test
^ close hand valve fully by turning clockwise
^ flush injector by operating lever several times
^ approx. 2 strokes per second
^ reduce the rate to 1 stroke per second
^ injector must chatter
^ observe spray paftern
^ must be conical and well atomized, a one sided spray pattern within a spray angle of 35~ is acceptable
If droplets form at the injector tip
^ replace entire set of injectors with Viton tipped
If spray pattern is straight (not conical)
^ replace entire set of injectors with Viton tipped
If spray is solid (not atomized)
^ replace entire set of injectors with Viton tipped
CAUTION
Always flush new injectors before
installing, using the US 8034 Tester, to
remove any foreign material that might
have entered the injector during shipping
or handling.