Alfa Romeo Forum banner

1 - 1 of 1 Posts

·
Registered
Joined
·
83 Posts
Discussion Starter #1 (Edited)
I decided to start a new thread with “FIXED” in the topic rather than posting this in the current 2 threads where the problem was originally discussed.
Some of you may know that I have been experiencing number 4 ignition coil melting repeatedly on my 159 3.2 Q4 over a period of several months. Other owners have also reported similar problems, some being on a different ignition coil though. In all the cases there have been no definite fixes.
It appears that my problem has been caused by less than perfect electrical earth connections. Since these connections have been cleaned the problem has not shown its ugly head again.
Here is the diagnosis and remedy for the problem I had. You will need a digital multimeter.
On the front bank you must remove the cover whereas if the problem is on the rear bank you will need to take the intake manifold off to get access to the ignition coil.
Press the START/STOP button (engine off).
Disconnect the corresponding cylinder coil.
Press the START/STOP button (panel on).
The pic below shows the pinouts on the connector when looking into the open end.
Measure the voltage between Pin 2 of the coil and the Earth, checking that it corresponds to the battery voltage.
Measure the voltage between Pins 2 and 3 of the coil checking that it corresponds to the battery voltage.
Measure the voltage between Pins 2 and 4 of the coil checking that it corresponds to the battery voltage.
In my case the readings between Pins 2 & 3 and 2 & 4 were slightly lower than battery voltage.
I then measured the resistance between Pin 4 of the coil and Earth terminal on the battery. This reading showed a resistance of less than 2 ohms. This should read 0 ohms.
Now, the Earth path goes from Pin 4 to a terminal connection on the cylinder head (the 3 ignition coils on each bank use a common connector on each cylinder head respectively). Clean this connection thoroughly. Under the battery tray there is a connection from the gearbox via a heavy cable to the vehicle body. You will have to remove battery and tray to get proper access. Clean both these earth connections. The final path is a heavy cable that goes from the vehicle body to the negative terminal on the battery. Clean these connections as well.
Reassemble and confirm that all previous measurements are now what it should be.

I hope this post will help others as well.
 

Attachments

1 - 1 of 1 Posts
Top