Pull the coil wires from distributor and reverse them and see if the non firing bank is now firing, if it is you bought a bad coil, it does happen. It is simple to do ,so do it.
Should always put new rotor with new cap.

 

I think it could be possible to pull the main plug from your working bank and coil and plug it to the non working and see if it follows. Meaning the other bank will fire while the other does not.

From memory there aught to be 3 wires to each coil at the main coil plug.

Also, the spade INSIDE the coils themselves have a habit of bending off center and when you push the main plug into the coil, one spade will move off to the side and not make contact, no spark.

Then, if you follow the wires from the 2 main coil plugs they lead into a harness that runs along the top LH of the engine. This is where ALL 12volts splits to coils, to ignition amps up front and (from memory) one of the sensors for coolant (I could be wrong about that last 12v split. Anyways, where everything connects at that point (at least on mine) was some shotty wiring and was producing real resistance...

There is one puzzling thing about this that I have read tho. If you are getting spark to half the engine, and you remove that coil wire (the good one) and put it on the "bad" side,,, the spark should then rightly power your BAD side. Are you saying that it doesn't?

This connection is about at the point where the wiring comes out of the LH harness with wires headed to the coils.

Disregard the large circle,,, focus mostly in the area of that little red horizontal line. That is the connection I mentioned above. Messy messy.

 

Hi Norman

There are literally dozens of things that could be causing the problem including a Short or maybe a break in the Wiring but here are some of the things that you could try as well as the suggestions made above

(1) Bad earth/ground somewhere

(2) Battery not fully charged

(3) Bad CPS giving intermittent Signal

(4) Wrong Gap in the Crank Position Sensor or a build up of Crud on the Sensor pick up, where the Gap for the CPS needs to be a Max of 0.042

(5) Burned or worn contacts on Rotor or Inside the Cap

(6) The White Coax Wire aka 'The Dreaded White Shielding Wire' (See Photo) this goes from the Engine Compartment where you see it in the Photo, all the way to the ECU in the Boot Trunk to Pin 24

Check the Continuity from the Engine Compartment to the ECU in the Boot/Trunk where it is only earthed at the ECU and not at both ends and then make sure that it is plugged in properly where you can see the join in the Engine Compartment and that the Contacts are Clean

As an extra double Check you could take some Coax TV Ariel Wire and run this from the join in the Engine Compartment round the outside of the Car to the ECU if you suspect that there may be a break in this Wire, as it isn't know as 'The Dreaded White Shielding Wire' for nothing

Last but not least for the Moment you need to take Precautions and Expect the Unexpected, because as your Car has been running on only One Bank of Cylinders, RAW FUEL is still being pumped into the Exhaust of the Bank that's not working (which could hold almost a gallon of Gas!)

Where if that Bank of 'Non Firing Cylinders' suddenly Bursts into life, then it could very easily set fire to your Car and then cause what has come to be known as a Marelli Fire, so maybe best to give it a day for any build up of Fuel to evaporate and even then have Fire Extinguishers ready just in case the worst should happen



White Shielding Wire to Pin 24 of the ECU

 

Macdoesit.
Thank you for your reply. As I have said many times there is no spark out of the new front coil so all that would do is stop the other bank running and maybe start a fire.
nofking

 

Jayjagjay.
Many thanks for the info and wiring diagram. If I interchanged High Tension wires on the distributor the ignition would be 30 degrees late so I am not going to do that.
I am going to check grounds and look for poor connections but it is 45 degrees here in North Florida today and I don't work so well in such bitter cold. I know - you wish it were 45 degrees where you are.
nofking

 

Orangeblossom.
Many thanks for the info. Going to look for a bad earth (ground) or other bad connection.
nofking

 

What I mint was, connect the working coil to the non working bank on the dizzy. Not the new coil.

 

Yes to checking grounds...

I would never suggest run and drive with the wrong HT lead. I didn't know about the change in timing due to swapping the HT leads, tho. All I am really suggesting is, even if it's for a minute or two, swapping the HT lead to see if you will get spark on the other (dead) bank. I guess you could try that with both coil to dizzy HT to rule out a bad HT coil to distributor wire as well. If you DID get spark to the dead bank by momentary swapping the HT lead to the dead bank, this would also rule out a problem in the cap and rotor itself.

In the diagram you can see that you will find a hard B+ feed at both coils. Then one on each that I think is a signal from the amp, then the last wires - one feeds the tach on one coil and ignition half,,, and then the second goes to a diagnostic port (that I think is rarely used by anyone). 3 WIRES in each coil harness plug. Did you say that you only have 2?

Also, check for a bent spade in the cavity of the coil, the female receiver for the plug OR a bum contact in one of the coil plugs itself.

Yes, check grounds. And, if the car is running, albeit only on 6 cylinders, check/probe with a DMM or even a test light, to see what you are getting from the wires on the dead bank. You'll find the 12v B+ lead,,, but what about the other 2?

 

JayJagJay.
I did say my car has 3 wires to the rear coil but only 2 to the front coil. I have looked and there isn't any spare wire which could have broken off the coil plug, in fact looking into the plug when it is off the coil I only see 2 connectors. I will try physically swapping the coils and feed.
I would expect one connection on the coil to be a pulsed feed and the other a ground or current won't flow so I will look into that today.
Nofking

 

The third wire on one coil is for Tacho. Marelli ignition V12's ran a 6 cylinder Tacho.
Has the new coil been verified good or is just an assumption due to being new?

 

The third wire on one coil is for Tacho. Marelli ignition V12's ran a 6 cylinder Tacho.
Has the new coil been verified good or is just an assumption due to being new?

 

JayJagJay and others who helped.
Finally running on 12.
I have always been suspicious why the front coil had 12 volts at either pole to the coil, but nobody thought that strange.
Finally bit the bullet and cut the white/black wire which I assumed went from coil to amplifier and connected a new wire.
Started immediately, no bang, no fire. I assume the wire is broken somewhere and touching a switched 12 volt wire. Haven't seen evidence of mice but I see other wires that are brittle.
Many thanks to all who helped
nofking

 

Brilliant!!!
Good work Man!
Really.
Must feel purty darn good to have figured it out!

Now, lol, to what's next!?
​​​​

 

Going to use a glue gun on any exposed wires that are cracking or look brittle, then, hey, I might just take her out and enjoy.
nofking.

 

Keeeeeep going. Open up them injector and ignition wire harnesses to see what's hiding under there... It's worth it.

 

JagJayJag
Hi Again.
Had a Porsche 928 many years ago and loved it.
The self adjusting valve rockers were noisy. I finally figured out the oil pump was above the sump and the seal was weak. Air was being pulled into the oil and wound up in the self adjusting valve lifters making them clatter.
nofking

 

I recommend pulling the distributor cap and removing the rotor held in with two allen head screws and inspecting it for condition. This photo shows the damage to the rotor that failed in my car. It was intermittent at first before the internal short was significant enough to short out to the distributor shaft. It seems to be an issue with aftermarket rotors and caps.