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Matt, Engineer
Category: Nissan
Satisfied Customers: 21857
Experience:  BEng hons Mech engineering, worked in auto industry for 22 years on engine, transmission and suspension design
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D21: , I'm having a problem with surging on my 86 Nissan

Customer Question

Hi, I'm having a problem with surging on my 86 Nissan pickup. It is the d21 style body.***** Z24i motor. I have changed both exhaust and ignition coils and modules. I have changed all spark plug wires. I have changed the distributor cap and rotor. And I have cut the exhaust pipe to verify its got flow and not a plugged catalytic converter. I'm currently doing the tests as you explained in a different thread. I have isolated the problem to the ignition coil side of the system. I'm having trouble identifying which wires are which and what I should have feeding the transistor assembly. What should I do

Edit...I just verified the intake side coil is not generating spark. Both the coil in the transistor module are brand new. I'm thinking for some reason its not getting power to it? Those are the wires I'm trying to identify.

Submitted: 2 years ago.
Category: Nissan
Expert:  Matt replied 2 years ago.

there should be a 12V feed from the fusebox to the module and and earth to the chassis / battery negative and then 2 wires feed from the switch module inside the distributor
Customer: replied 2 years ago.

I already know that. What I'm trying to do is identify the wires because they don't match the colors on the schematic that I have.
I'm using the schematic found in the chilton's manual.

it is also found here....

it's the one for the 86 D21 z24i fuel injected 4 cylinder

It shows a blk wire to ground, a grn/yel to terminal 5 on the ECCS (whatever that is), blue wire which turns to white before the transistor, and a brown wire.
I'm checking at the plug before the transistor (or what I have been told is called the ignition module). The colors present on the harness side of the plug are a BLK/White, Blk/Pink, a white wire that is shielded, and a blue wire.

Expert:  Matt replied 2 years ago.
Hello Frank

the white shielded wire will be the one from the ECCS unit (pin5) as thats the speed signal as these need to be shielded to work

so you should be able to confirm that the black an white wire is 12V power from the ignition switch

and also trace the wire from the distributor back the module so this should leave few enough wires to trace and confirm
Customer: replied 2 years ago.

So I unplug the wire from the bottom of the distributor that goes to the condenser. It is a black colored wire. Started the motor and the problems seem to have changed for the better. is it possible that the condenser could be causing the intake side coil to not generate spark. As if it is stuck one way or the other. Looking at the schematic it appears that there are two open contacts 1 to the ignition coil on the intake side 1 to the ignition coil on the exhaust side. Not understanding how this condenser works or what it does, I'm wondering if this is the problem.

Expert:  Matt replied 2 years ago.
Hello Frank

thanks for the extra information

the condenser is there to extend the signal from the distributor to make it more suitable for the module

what can happen they can short out internally with age so you end up with no signal at all into the module

so the engine will run without the condenser but you will shorten the life of the module so its a good idea to replace it quite soon

glad you got it sorted
well done
Customer: replied 2 years ago.

So a little bit more information and I think I'll be close to finished. I have confirmed that the black/pink wire shows 0.2 ohms to ground so I'm assuming that it is the ground wire, on the schematic that wire is shown as a plain black wire if I'm right. Both the black/white and the blue wire on the harness side show better than 30 ohms to ground. with the ignition key turned forward I do have 12 volts on the black/white wire. I have not checked the blue wire yet. on the schematic I'm going to assume that it is the wire going to terminal 5 on the ECCs control unit. what should I be showing on it and in what state of the ignition switch being turned.

edit..... I just noticed next to the wire I'm speaking of on the bottom of the distributor which upon second observation looks like it might be a ground. There is a loom with like four wires in it that goes over to the passenger side of the motor and disappears into a harness any idea what these wires are? And could this be part of my problem

Expert:  Matt replied 2 years ago.
Hello Frank

the wire that runs back the ECCS should be shielded and I thought that was white?

in any case you shouldn't see anything on that wire unless the engine is running and even then you'll need to measure AC voltage as you should have an alternating voltage / sine wave voltage thats coming out of the distributor
Customer: replied 2 years ago.

Now I'm just more confused. I did edit my last question possibly after you answered. Would you mind re reading my last post?

Expert:  Matt replied 2 years ago.
hello Frank

Ok I didn't see that edit
and I was getting a little confused myself as the blue wire turns into the white wire that runs back to pin 3 of the ECCS

that one I think will have no signal unless the engine is running

the green and yellow wire is the same as the blue and white wire to the exhaust module unit and I think that will be a 5V supply with the ignition on

hopefully a new condenser will sort out your issue
Customer: replied 2 years ago.

So now I'm scouring the internet trying to A. find one and B. what it even looks like so I can identify it in the engine compartment. Is there anything you can do to clue me in to where it is located and what it looks like? Did you see my comment about the other four wires that are attached to the bottom of the distributor next to the wire that I said is colored black

Expert:  Matt replied 2 years ago.
Hello Frank

how about this

as for the 4 other distributor wires then I don't have information about that I'm afraid
Customer: replied 2 years ago.
Relist: Incomplete answer.
I am still not able to fix this issue with the information in this thread.
Expert:  Matt replied 2 years ago.
OK Frank I'll opt out
and get another expert to try and give you the help required

good luck
Customer: replied 2 years ago.

Thanks Matt

Expert:  Matt replied 2 years ago.
Ok don't reply to me otherwise it'll lock back to me

good luck