Fuel Injectors. Checking And Replacing - BMW 5251 Service Manual

. . .-
/Fuel lnjeciion
NOJE-
With engine oft disconnect harness connector and checlc
heating element resistance between white wires on the sen-
sor side of harness. If the element is electrically open (no
continuity), replace sensor.
-
If oxygen sensor does not produce a fluctuating voltage and
preheater circuit is OK, replace sensor.
NOJE-
If not already applied, coat oxygen sensor threads w ~ t h anti-
seize compound before installat~on. Do not get the com-
pound on the sensor tip.
Tightening torque
Oxygen sensor to exhaust system
55
Nm
(41
ft-lb)
Fuel injectors, checking and replacing
The fuel iniectors are switched on and off (oaened and
closed) by'the ECM. The injectors are connkcted to acom-
mon power source. A ground signal from the ECM is used to
open and close the injectors.
CA U J I O G
Use only a digital multimeter or an LED injector tester when
testing injectors or wiring. Use of an analog VOM or incan-
descent test light may damaqe the engine controlmodule.
4
Remove fuel rail cover. See 110 Engine Removal and in-
stallation.
With the engine running, place the point of a long screwdriver
on each injector and check for a cliclting vibration. If no vibra-
tion is found do the voltage checit shown below.
Injector electrical loom removal:
-
Loosen mounting nuts A.
Remove ground wire C.
Disconnect ignition coil harness D