z24, what triggers the secondary coil?

[Farmer Joe]

wife and i picked up an 85 720. 

 

runs well, but only on the primary coil. 

 

sooo, what would make just the primary run? 

 

the secondary coil is good. swapped it with the primary and it ran. 

 

the fuse in the #1 spot on the fuse box is fine. 

 

 

 

all the connections from the distributor to the coils is correct, and it seems to be right to the ecc... 

 

what does that ecc box do in this whole mix?

 

 

any help would be awesome.. 

 

thanks

 

[datzenmike]

Check for power on the + terminal of both coils. 

 

No power on the exhaust coil.... change the fuse never trust it to looks.

 

 

 

If you have power on both coils..... does your distributor have 4 wires to it? Three together in a harness and a forth White one with it's own separate plug? Find the plug, and unplug it. Got spark now????

 

[Farmer Joe]

No white wire like you explain. Ive got 4 wires from the module that terminate at a 4 or 6 pin connector. There's a ground that connects on the outside of the case on the distributor.

 

Ours doesn't have the eyelet ends like that pic.

[Farmer Joe]

https://imgur.com/gdOfvAX

[wayno]

There is a ground over by the carb that has to be connected, if it isn't grounded, only one coil fires, it's right over next to the carb harness.

See the stupid ground wire in the photo I didn't have grounded on the left near the wrapped wires that go to the fusible link.

[datzenmike]

Do you have two wing nuts on the air filter??? If so you have a crank angle sensor and the coil is fired by the ECU. That I know very little about.

 

If you have one wing nut the distributor should have the 4 wires I posted a picture of. The White wire is grounded by a vacuum switch to turn the exhaust side plugs OFF under heavy load. If this switch has failed or stuck the exhaust side will not be on. Unplugging the white wire leaves the exhaust side permanently ON.

[HRH]

If it's a Z24i, it's controlled by the ECU.  Secondary coil shuts off after 3000 rpm and under hard load.  Reason they give in the FSM is too much noise from the engine operating all 8 plugs at higher rpm or load.  I still think that's straight bullshit from Nissan, but meh, maybe not.  I never did bypass that and run both all the time.

[datzenmike]

Do you have two wing nuts on the air filter??? If so you have a crank angle sensor and the coil is fired by the ECU. That I know very little about.

 

If you have one wing nut the distributor should have the 4 wires I posted a picture of. The White wire is grounded by a vacuum switch to turn the exhaust side plugs OFF under heavy load. If this switch has failed or stuck the exhaust side will not be on. Unplugging the white wire leaves the exhaust side permanently ON.

 

 

One wing nut is a Z24 and the distributor module fires intake and exhaust together at all times. Simple.

[Farmer Joe]

okie dokie, 

 

so im still workin on this issue. 

 

replaced the module today, but the trailing set still dont fire.. 

 

made a new tool..

 

 

got the junkyard one freed up from the advance plate... 

 

 

had to modify it a little bit.. 

 

 

to get this bastard off without breaking it.. 

 

 

 

 

all that and still isnt working and no new ways to isolate it further that i can think of... 

 

help!?

[datzenmike]

I came in kind of late but...

 

You must have 12 volts on the + side of both coils

 

Negative side of coils are grounded off and on by the module to fire them

 

Swap coils. If problem swaps the coil is bad. If problem stays with that coil then distributor.

 

 

 

 

 

I assume the Red/Orange? wire is the 12 volts?

The two wires on the left go to the coils???

 

Disconnect the white wire. This is the switch that tells the module to turn off the exhaust side coil. It's either disconnect it or ground it that does this. I forget.

[Farmer Joe]

well i got it figured out.. 

 

took the multi meter to it and found out the trailing coil was only getting 2 volts on the power side. tested and did a jump from the battery to the coil and it started working. decided to just share the 12v from the leading coil for the trailing coil and it works great now. 

[datzenmike]

The intake side is powered directly from the ignition.

 

The exhaust side from the second fuse over from the left hand side of the fuse box. You could try replacing it or making side that it's making good contact.