Checking the Engine Sensors
There is a photo below indicating where some of these parts are.
a) Cleaning the high-tension
ignition components.
I removed the distributor cap and rotor for cleaning. The inside of the cap
was a bit dirty. I washed the parts in soapy water as these can't be easily
and cheaply replaced in NZ. It pays to note that the glossy finish on the red
plastic resin is fragile and should not be cleaned with an abrasive. I also
wiped down the plug wires and caps with a mentholated spirits. One of the plug
caps was slightly mangled so I filled the holes with silicone RTV. I checked
the resistance of some of the wire assemblies - no problems there and none expected.
b) Replacing the two small
vacuum tubes.
Although the original tubes were not leaking, they were severely deteriorated.
The new rubber tubing should have an ID of 4mm and one meter length is sufficient
for both applications. One supplies vacuum to the fuel pressure regulator such
that the pressure is maintained relative to intake manifold pressure. The other
draws air from the middle of the crankcase breather tube, although it looks
simply like a designed-in bad vacuum leak to me. I think this tube combined
with the large breather tube mimics the PCV valve function seen on other cars.
c) Checking the Crank Position
Sensor.
This is a "Hall Effect" type sensor mounted .030" - .050"
from a toothed wheel on the front end of the crankshaft. I checked the gap,
the alignment with the wheel, and the resistance spec at the connector as 540
ohms +/-10%.
d) Checking the Cylinder
Identification Sensor.
This little gem is located on the No. 6 cylinder HT wire as it exits the distributor
cap and provides a signal to the DME when that cylinder is fired. According
to roadfly.com wisdom, the only purpose
of this is to allow the DME to coordinate fuel injection pulses (into two sets
of three injectors) with cylinder firing for a smoother idle. Apparently it's
not that important that it works - a good thing as spares are reputed to be
hard to come by. Currently I don't what the correct value should be.
e) Checking the DME Temp
Sensor.
The spec from Bentley is 270 - 400 ohms at 80° C (176° F), 2K1 - 2K9
ohms at 20° C (68° F). Mine was 260 and 2K7 ohms.