This article is about use of coilpacks also known as COP's (Coil on Plugs) which are common on many Toyota engines.
The bulk of the information and the first picture on this site where courtesy to Anthony Kellam
Coilpack basics:
Just about all of the new Toyota
engines use a coil-pack for ignition. Where previously a single/double
engine bay mounted coil was used with a distributor or external coils
for pairs of cylinders coilpacks are an all in one solution for each
spark plug. The are a very compact ignition coil which is designed to
fit directly onto the end of the spark plug.
Not pictured are 2AZFE Camry and 2NZFE. Both of these are longer types,
which are useful when some extra reach is needed. Similar in length to
the GXE10 (2) coils pictured above.
Fitment of coilpacks to a 20V engine:
The inside diameters of the spark plug
tubes on a 20V engine are 24mm, unfortunately the outside diameter of
the most compatible coils are close to 24.4mm at their highest. So to
make them fit the cols needs to be machined/shaved down to suit. This
can be done crudely with a file or at best in a lathe using a 4 jaw
chuck and a great deal of care. Also to note if these are to be
machined use a high speed steep cutter that goes to a very sharp
pointed tip and with no radiused edge. Below shows an unmodified coil
on the left and a coil that has been machined in a lathe on the right,
both are from a 1NZ engine.
By far the best fitment for a
20V engine is a 1NZ coil as above. This is shown here installed on the
right, to the left is a 1ZZ coil. The space from the cam cover to the
bottom of the clamp on the coil for a 1NZ coil is 8mm, for the 1ZZ coil
it is greater. It is reported a silvertop cam cover can be fitted over
1NZ coils if correctly positioned, although it does raise the question
of adequate coil cooling when under a well fitting cover.
Electrical Connection:
Unlike other companies coils which
more
commonly have just use an encased coil with a twin wire connection all
Toyota coils have an inbuilt igniter. This means they can be run
directly off the ECU's ignition output without any ill effect. The
tell-tale sign of an coil with an inbuilt igniter is a 4 wire
connection instead of 2. The pin connection for almost all Toyota coils is shown as below:
Pin 1- Earth: Constant ground, join all the coils together and ground to the body, grounding to the cam cover is not suggested at all.
Pin 2- IGT:
Ignition triggor, this is the signal wire to activate the internal
igniter, it can be connected directly off the output of any ECU even
with multiple coils in parallel.
Pin 3- IGF:
Ignition feedback, after the coil fires this pin sends a
confirmation of firing. Not needed for any aftermarket ECU, however if
not connected on a factory ECU it will go into a fault mode. For 20V
owners using the OEM ECU the
signal from only one coil (any
coil) is needed to go back to the ECU.
Pin 4- +V:
Switched power, power feed switched when ignition is on. The easiest
and likely the best way is to just use the power feed from the original
coil and then power all four of the new coils instead.
Mounting:
As shown in the previous pictures all
of the Toyota coils are secured via the use of a single mounting tab.
To adapt this to other engines it can through various forms such as an
adapter plate, bosses welded to the cam cover or even the friction of
the coils in the tube.
Shown is an adapter plate from the parts section that is now available. It's bolted to the
middle of the cam cover of either 20V engines. It uses the three blind threaded
holes originally used for the spark plug lead clips. For more information please see here: 20V Coil-pack/COP Adapter plates:
