|
LIVP Oil Pressure Question (TSIO550E)...Fluctuations Noted
My first suspicion would be an electrical problem
with or around the oil pressure sensor. You mentioned that you rigged a
ground wire. Depeding on how it's hooked up it may or may not affect the
problem. I've seen some engine sensors read erratically because of where
the ground lead from the engine interface box (the box all of the engine
sensors are wired to) was physically attached. The problem may
affect multiple sensors, or only one. For example on a Legacy using a JPI
engine monitor the installation manual said to attach the ground wire from the
engine interace box to the engine block. We first tried an unused
stud (it was real convenient) on the back of the engine where the
vacuum pump would be, if it had a vacuum pump. The tach reading
jumped all over the place. We removed the ground wire from that stud and
attached it to the large ground stud running through the firewall to the
engine. The tach worked fine after that. After thinking about it I
suspect attaching the ground wire to the vacuum pump pad created a
secondary return path from the engine back to the rest of the system that
was in parallel with the primary return path (a "ground loop"). Bad.
What type of oil pressure sensor do you have?
Is it a 4-wire sensor? A 3-wire sensor? Single wire sensor? If
it's a multi-wire sensor does its ground wire run back to the engine interface
box? If it's a single-wire sensor, and the sensor case isn't attached to
the engine, then the case of the sensor should probably have a wire running
back to the same ground as the engine interface box. Does the installation
manual specify how to ground the sensor?
Tom Gourley
|