The rebuild has finally started today and so far in a few hours I've managed to completely strip the interior.

 

 

 

Next job on my list is to get both the bumpers, tailgate and bonnet off.

 

After that i'll work on the body panels and stripping down the engine.

I’ve pinged you a message mate

Feel your pain that drivers side oil feed is a bitch. The passenger one isn’t much better.

So the next pain in my side on my zed is now an electrical issue.

 

Seems i have no spark on the coil packs.

 

Tested the ignition relay by testing voltage between pins 1 and 2 and then cranked the ignition but i get 0 voltage.

Have you removed and reconnected the main plug onto the Link ECU and are you 100% sure it has fully seated?

yeh, tried that a few times.

 

The ecu only controls the negative side on pin 16, the other side goes to a fusable link holder, but not sure which one it is.

Taken from the oz site :

 

Some (long winded) assistance?

 

The ECU earths pin 16 when the ignition is turned on. This is probably by a 'pull down' or 'open collector' transistor inside the ECU. Sorry if this is obvious to some, but a transistor has three connections, a base, collector and emitter. It's really just a switch. When voltage is applied to the base by the cpu (computer chip that runs the ECU), the collector becomes electrically joined to the emitter. If is is a transistor, the base would be connected to the cpu, probably via a resistor, the emitter would be permanently connected to ground (earth), and the collector will be connected directly to pin 16. When the cpu wants the ignition relay ON, it sends a voltage to the base of the output transistor, which then connects pin 16 to earth by joining the transistor's collector to its emitter. This supplies an earth to the ignition coil relay, which always has 12 volts connected to it, so it turns on.

 

Pin 16 is connected to one side of the coil of the ignition relay. Once again, apologies if it's obvious, but relays are just electro-mechanical switches too. They have a pair of spring loaded contacts and a coil. When voltage is applied across the coil, it creates a magnetic field which pulls one contact onto another, to close a circuit. The 'click' you hear when a relay is energised is one contact being pulled against the spring onto the other contact. Some relays can be 'normally open' (with no power, contacts are open, or apart), normally closed (with no power, contacts are together, or closed), or both if they have three contacts (a centre contact normally sits on one contact, and is pulled off the first contact and pushed onto the second contact when energised). The main advantage of relays is that you can use a very small amount of power to energise the coil, which closes much larger contacts to enable a much larger current to flow through the relay. The Zed ignition coil relay is a 'normally open' type. Looking at the bottom of the relay, the two widely spaced contacts are the coil contacts. The closer contacts are the normally open contacts. Pin 16 is connected to one of the coil contacts, and the other side of the coil is connected to 12 volts all the time via one of the green fusible links in the engine bay. This is why you can see 12 volts at the ECU pin 16 connector when the ecu is disconnected and/or ignition is turned off. If you can't see 12 volts on pin 16 of the connector when the ecu is unplugged, then you've got a blown fusible link, busted relay coil, broken wire or dud connector E12/F25 - this is the only connector between the ECU and the relay, and I think it's inside the passenger guard, but I'm not 100% sure. This is also where the resistor is that drz400y has mentioned, but I don't think the resistor has anything to do with the ignition circuit, as it is fitted in autos only.

 

The two main contacts of the relay are connected to another green fusible link on one side (which gives it its 12 volts supply), and to the power connection of all 6 ignition coils on the other side.

So tracing the fault i found a 10amp ignition fuse blown,

 

Replaced it and it blew again.

 

Seems i have a short somewhere.

You’re getting there slowly but surely Lee, keep at it and she’ll be ready for the summer :thumbup1:

Just to confirm, the ignition 10A fuse that is blowing is a red herring as it does not supply power to the ignition coil relay, it uses the ignition relay to power things related to the cruise control and auto box so it’s likely that you have not seen an effect of it being blown at this stage. The problem you have with that fuse is either related to your retrofit cruise control or the manual conversion but you can worry about that later.

 

Your ignition coil relay is what you need to focus on as that is what isn’t being powered here. I’ve not reviewed a pinout of the relay itself but the switched section receives 12v direct from the battery via the green fusible link in the engine bay titled IGN, I’m assuming this is what you’re referring to as pin 5 and this will give power to the PTU. In order for this relay to power the PTU, it requires the coil in the relay to be energised (across pins 1 and 2?), the power supply for this comes from a different fusible link in the same box titled FUEL PUMP.

 

The wiring diagrams clearly show that this feed not only powers the fuel pump relay, but it also energises the coils to close the ECU and ignition coil relays so without both of these green fusible links in, you won’t get a spark. If you’re pulling the fuel pump fuse when cranking to troubleshoot, you’ll be inhibiting the ignition system.

 

This is not from experience as it’s just from reviewing the wiring diagrams which I am “assuming” are also applicable to your late spec car for this system. Someone with more hands on experience may be able to prove otherwise but from what I can see, to safely test for a spark, you would want to pull the fuel pump relay and crank with both of those green fusible links in the engine bay installed.

 

Test for a spark again configured as above and report back so we can methodically work through your issue.

Edited January 14, 20197 yr by Joely P

And if you’re a little confused Lee, JoelyP and i we’re talking about the problem last night.... he’s not hacked your phone or anything

Out of curiosity, did the link require any adaption or special wiring amendments to function on your late spec car? Am I right in thinking that the permanent live to the injectors are switched on the later cars? The power supply to the injectors is from pin 58 on the ECU and this is the same supply to the coil to energise the ignition coil relay etc. Checking for 12v on pin 58 is an easy way to ensure you have power to the relay with those green fuses in before you move onto a crank test.

Out of curiosity, did the link require any adaption or special wiring amendments to function on your late spec car? Am I right in thinking that the permanent live to the injectors are switched on the later cars? The power supply to the injectors is from pin 58 on the ECU and this is the same supply to the coil to energise the ignition coil relay etc. Checking for 12v on pin 58 is an easy way to ensure you have power to the relay with those green fuses in before you move onto a crank test.

 

The diagrams in the link below show the 90-94 and 95 on harness changes:

 

http://www.twinturbo.net/nissan/300zx/forums/main/view/1045147/-Rehosted-images-.html

 

You can see which fusable links need to be in place for the spark and ignition circuits to get their power. The Pin 58 to Pin 45 change

was only for the injectors.

So is there injector cabling changes i need to be aware of?

 

The ecu itself is operational and is powering up and reading all sensors.

 

Prior to this spark issue which might not even be an issue based on the information presented by Nick and Joel

the engine cranks perfectly fine (when i have a charged battery) but just wont start, so the presumption was to

be either fuel or the spark.

 

The diagrams in the link below show the 90-94 and 95 on harness changes:

 

http://www.twinturbo.net/nissan/300zx/forums/main/view/1045147/-Rehosted-images-.html

 

You can see which fusable links need to be in place for the spark and ignition circuits to get their power. The Pin 58 to Pin 45 change

was only for the injectors.

It was plug and play,

 

Initially it wouldn't power up but discovered that was because the ecu plug was not in tight enough.

 

Out of curiosity, did the link require any adaption or special wiring amendments to function on your late spec car? Am I right in thinking that the permanent live to the injectors are switched on the later cars? The power supply to the injectors is from pin 58 on the ECU and this is the same supply to the coil to energise the ignition coil relay etc. Checking for 12v on pin 58 is an easy way to ensure you have power to the relay with those green fuses in before you move onto a crank test.

So is there injector cabling changes i need to be aware of?

 

The ecu itself is operational and is powering up and reading all sensors.

 

Prior to this spark issue which might not even be an issue based on the information presented by Nick and Joel

the engine cranks perfectly fine (when i have a charged battery) but just wont start, so the presumption was to

be either fuel or the spark.

 

None that will cause an issue if no changes have been made to your harness. Your presumption of either fuel or spark is correct but we just need to isolate exactly how. If you are definitely getting a spark we can then look into the firing order and the fuel scheduling. You also need to be 100% sure that you have connected both the coil packs and the injector connectors up correctly so you’re not chasing your tail!

It was plug and play,

 

Initially it wouldn't power up but discovered that was because the ecu plug was not in tight enough.

 

That’s not a problem, the link from Andrew clarifies the alteration in the injector power supply which is just a modification in the later harness and will not affect an ignition issue. We know that you have power to the injectors as it keep filling up your pots with fuel!

I'm running a wiring specialists harness anyways so again completely different :)

 

That’s not a problem, the link from Andrew clarifies the alteration in the injector power supply which is just a modification in the later harness and will not affect an ignition issue. We know that you have power to the injectors as it keep filling up your pots with fuel!

I'm running a wiring specialists harness anyways so again completely different :)

 

I understand you’ve had the car running ok with that harness though right?

I understand you’ve had the car running ok with that harness though right?

 

It came from my last zed and worked fine.

So is there injector cabling changes i need to be aware of?

 

The ecu itself is operational and is powering up and reading all sensors.

 

Prior to this spark issue which might not even be an issue based on the information presented by Nick and Joel

the engine cranks perfectly fine (when i have a charged battery) but just wont start, so the presumption was to

be either fuel or the spark.

 

Don’t entirely agree with that. From the video chat we had the other week, it sounds like it’s spinning enough to potentially start, but still sounded like a fairly slow crank over, and it significantly drains the battery after 2 or 3 start attempts. That, in my eyes, is not normal. It may be a symptom of your issue (an electrical gremlin somewhere sapping power and preventing a start) or it may be unrelated... I’m not sure.

 

Once you/we have verified you have a good spark, as Joel says, would be wise to the verify the correct plugs are attached to the correct coils and injectors. We know you have fuel as it floods, so next step would be to check its firing the plug st the correct time and firing the injectors at the correct time.

 

At least we have learned something new, that the fuel pump fusible link is connected to the ignition coil relay.... always thought they were independent circuits!

Battery now has full charge :)

 

Put plugs back in, along with the coil packs then put the ecu back .

 

After plugging the fuse back in for the fuel pump i can confirm the relay previously mentioned has power on both pins that it needs.

 

Just nipped in for a quick coffee and heat up and i'll go back out and work on doing a spark test.

 

I'll just pull the fuel relay as you mention previously.

Just over a month since my last update and i had a bit of success today i thought i'd post a few videos.

 

Previous issues were presumed electrical but after alot of diagnostics and tinkering i'm fairly sure its now just down to fuel.

 

My own timing gun refused to work so i borrowed a old but known to be working version to set the timing.

 

Fuel relay out i got the timing mark as close as possible to 15.

 

Then i gave her a crank of the key.

 

[video=youtube_share;K1ffIRlYSTU]

 

Much smoother, but after i put the relay back in and gave er some fuel she instantly died again.

 

Thinking its far too much fuel i set the master fuel level on the ecu lower and tried again

 

[video=youtube_share;dMtMi1BK7Tc]

 

This time she started and lasted about 30 seconds before cutting out.

So after trying to start my zed many times with various fuel setting i've managed to foul up my plugs ever so slightly.

 

4 of them are a little worse for wear so i've ordered a new set, after which i'll start the process again.

 

Hopefully after the new plugs arrive i will have her started by the weekend.

 

Another nasty job done that well and truly needed it; gearbox oil change.

 

You wont believe the colour of what came out prior to putting new oil in.

 

Never had a oil pump so removed the shifter support bracket and used some hose pipe.

 

Stop procrastinating and get it running!!