900 L4-1985cc 2.0L SOHC (1988)
Fuel Injector: Technical Service Bulletins
Fuel Injectors - Testing With VITON Rubber Valve Seats
Category
Engine
SECTION
PAGE
2
10
ISSUE
CODE
03/91-0096
242
Subject:
Testing CIS Injectors with
Viton Valve Seats
Application:
1988 900 Models with CIS Fuel Injection
New fuel injectors are available to improve driveability on 1988 900 models with CIS fuel injection (see PSI 08/90-0018). The injectors, P/N 78 56 354,
contain a valve seat made of Viton rubber which has improved sealing characteristics to reduce the potential for rest pressure leakage. The Viton rubber
seat affects the opening pressures of the injector and requires a revision of the service testing specifications.
Figure 1
The new injectors can be easily identified by the brass-colored valve tip as well as the Bosch part number 0 437 502 056 stamped on the body of the
injector (Fig. 1).
The specifications for testing these injectors are as follows:
Opening Pressure Test
Note
A new injector that has never been used in a vehicle must be flushed on an injector tester before checking otherwise its initial opening pressure may be
higher than the specification.
New injector
3.4 - 4.0 bar (50-59 psi)
Note
The test values for opening pressure will change depending on the time interval between injector removal and testing.
Used injector
3.1 bar (45 psi) or higher
(less than 3 hours after removal)
Used injector
3.0 bar (44 psi) or higher
(3 hours - 24 hours after removal)
Used injector
2.8 bar (41 psi) or higher
(more than 1 day after removal)