The ECU has to have a very good understanding of the
engine’s current crank angle. Setting the base timing is a
critical part of the ECU setup and tuning process.
Sample Timing Mark
First of all, you must have timing marks to be able
to do this. Many engines, especially older ones, will have
these on them from factory. Sometimes they are at funny
positions, for example the FD 13B engine has a single mark at
20 degrees ATDC.
FD 13B engine timing mark
If there is no timing mark on the crank pulley, you
can determine where TDC is by pulling out a spark plug and
rotating the engine by hand to see where the spark plug gets
to the top. If you have put a screwdriver down the hole and
use that to move a dial gauge, that will get it to within a
degree or so. If you can’t, or you don’t have a dial gauge
then you can screw a bolt into the spark plug hole and roate
the engine until the piston touches the bolt near TDC, and
mark that position on the crank. Then rotate the engine back
the other way until it touches the bolt from the other side,
and mark that position. TDC is halfway between those two
marks. This assumes that you have a running engine that will
idle by itself. You will need a timing light; the dumber and more
basic the better. If you’re using a timing like that has
intelligence in it and advances or retards the time of the
flash relative to the ignition trigger, then you must disable
that. On COP engines, there’s no ignition lead so you can’t
clip the pickup on the lead. In most cases you can clip the
pickup on the leads at the back of the ignition coil, because
the common mode current is the same as the high voltage
current by Kirchoff’s current law. I have never seen this not
work, but if it fails you can remove the coil and connect an
ignition lead between the coil and the plug. On some Nissans,
they have a timing loop which you are supposed to be able to
clip your timing light onto, but in my experience this often
doesn’t read correctly so I recommend against using that.
Timing light clipped onto the back of the COP
In Eugene, go to the inputs -> triggering page,
and enable the timing lock. You will need to select a value
for the timing lock angle, based on the angle of the timing
mark that you have on the engine. For the RX7 engine, you can
select the dedicated 13B RX7 trigger mode, which locks the
leading ignition timing to 5 degrees ATDC and the trailing to
20 degrees ATDC, so that you can use the factory timing marks.
Enable timing lock
13B RX7 trigger mode
Then check the timing with the timing light, and
adjust the ignition timing using the up and down arrows to
change the base trigger angle until the timing light shows the
same number commanded by the ECU. You should also increase the
revs and make sure that the timing stays still.