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gvincent

Turbo swap 78 280Z NO Spark

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I am at a lost trying to figure why I can't get any spark on my turbo swap project. I am putting an 83 turbo motor in my 78 280Z. I have ruled out the distributor as I am getting both high and low signal to the ECU computer, I can hear the injectors clicking while cranking, I have correct fuel pressure. I have changed out the coil and even tried the GM HEI module swap in place of the ignitor transistor. I have the Black/White wire with 12V connected to the coil+, the blue wire from the ignitor to the coil- terminal. I have a yellow wire, not a yellow/white wire which most people say i should have connected to the ignitor. this wire is in the same 78 280Z harness coming from the 8 pin connector at the 83 turbo ECU, I checked it with an analog meter on low scale and you can see it swing from 0-5volts, now the blue wire in that harness also is reading the same is this correct? There is a white/black wire which I don't know what it is for. the ignitor is grounded with a black wire.
Now i had this engine running 4 years ago although not very well I think it was low spark from the old coil. All the wires come from the 78 harness that goes to the 8 pin connector with was wired to the 83 ECU 8 pin connector. I haven't hooked up the blue tach wire as I was told I need a resistor but couldn't find a value anywhere yet.
I'm lost trying to figure what to check next. Anybody have a spare 83 Turbo ECU I can borrow

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The "T" connector on the Ignitor does NOT have a ground. (the ignitor gets it's ground from the bracket which should be connected to the body) It should be Black/White (+12v at IGN ON) on the top spade of the ignitor connector and ECU signal (pin 5) on the leg.  The ignitor then feeds +12v to the "+" coil via a B/W. There shouldn't be any another connection to the "+" side of the coil.

 

(Stock 280Z will have a B/W in the engine bay harness that goes directly to the coil "+". The turbo engine coil is not wired that way - the B/W goes to the ignitor. The coil "+" should already be wired to the ignitor in the stock 280ZXT coil/ignitor assembly...)

 

You can use the stock 280Z Blue wire that was attached to the 280Z coil "-" to drive your Tach - IF you remove your stock 280Z Electronic Ignition Module (which you should have done anyway while doing a turbo swap). That Blue wire originates at the stock EIM as the coil "signal to fire" and tees off to drive the Tach. The Tach signal goes through a resistor in the dash harness. If you disconnect the Blue wire from the EIM it then becomes just a Tach signal (which will run just fine off the 280ZXT coil/ignitor)...

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Hi, Thank you for your responses, I am headed to the shop to try a few other things today. Yes the black/white wire is connected to the ignitor spade connector and I have a yellow wire connected to the other spade connector. there is a B/W wire from the ignitor going to the + coil terminal. There is a blue wire on the coil - terminal

 

Ignition in on position 12 volts present at + coil terminal

 

Cranking using an analog volt meter on 0-5V scale the yellow wire is receiving a signal, jumps from 0 to 5V

Some people say it should be a yellow/white wire but all I have in that harness is yellow.

 

Cranking using an analog volt meter on 0-5V scale the Blue wire is ALSO receiving a signal, jumps from 0 to 5V is this normal?

 

Now I noticed with a spark indicator light on the output of the coil that there was a single spark every time i turned the ignition on and again when I turned it off

Second thing i noticed that while cranking there was no voltage on the positive terminal of the coil?????? Bad Ignition switch?

 

Going to try a jumper wire from the battery to the ignitor and to a remote starter switch with ignition in the ON position today to bypass the ignition switch.

Going to search for this black box somebody mentioned that is under the dash on the passenger side, but if it was for the stock 280Z it was probably removed because that motor, harness etc. went into a 240Z that is running.

 

I don't know what else to check, green light visible on ECU, yes.

Now I had this thing somewhat running 4 years ago, badly but at least would start and run if I just feathered the gas, figured it was a fuel problem. took it apart, installed an intercooler custom fuel rail new injectors and new connectors, new fuel pump, hoses and a gauge  and put it all back together and now no spark.

 

I'll post back what I find

Thanks again

Greg

 

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Happy New year, Finally got a chance to get to the shop and try a few things.

we tried a remote start and put a 12v source to the positive coil because we were not reading 12V at the coil while cranking but we do have 12V with ignition on.

 

Now we seem to be going backwards as now we no longer have the 0-5V pulse on the yellow wire on the ignitor or the blue wire as I mentioned in my post above.

we looked on the passenger side and yes there is a "black box ignition/transistor"thing that another forum suggests that I check. Now wasn't this box for the 280Z? Is it still needed with the 83 280ZXT? Could it be causing problems with the 83 turbo ECU? I don't know if that Ignition box could be getting any info as the 280Z distributor/motor etc is no longer there.

 

getting frustrated and being an ole geezer I don't have any hair to pull out.

 

Don't know what to try next until I found out what to do with the old 280Z ignition box

we have double checked the wire connections per the Info above, but like I mentioned I have a Yellow wire, a Blue wire, a Black wire, a Black/White wire and a White/Black wire in the harness going through the firewall. I do not have a Yellow/White wire that is on the wiring info given to me in the Post above by 1970 240Z

 

Any info about the ignition box or other suggestions would be greatly appreciated

Thanks,

Greg

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On 1/7/2020 at 8:37 PM, gvincent said:

 

we looked on the passenger side and yes there is a "black box ignition/transistor"thing that another forum suggests that I check. Now wasn't this box for the 280Z? Is it still needed with the 83 280ZXT? Could it be causing problems with the 83 turbo ECU?

 

Yes, that's the electronic ignition module for the 280Z. It needs to be disconnected (removed) as I said above. But let me simplify this:

 

ALL you need to spark an L28ET with a stock 280ZXT coil and ignitor is:

 

- Black/White (constant battery voltage (+12v) at IGN ON) to top of "T" (2-pin connector on ignitor)

- Yellow (Y/W - who cares) to "leg" (bottom) of "T" (2-pin connector on ignitor) FROM ECU pin 5

- The coil bracket must be bolted to sheet metal (meaning it HAS to be grounded).

- The ignitor -> coil wiring needs to be as stock 280ZXT (meaning: Black/White wire from ignitor to coil "+" - Blue wire from Ignitor to coil "-"

 

That's all.

 

The signal to the Tachometer is lost in the above scenario, but that's easily remedied.

 

Next time you post - Pictures!

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I would start with when this happened you mentioned 4 years ago it was running. And then what suddenly no spark? Can be a couple of things. I would start troubleshooting backwards if that helps. You mentioned You swapped an HEI module why did you do this? Pull out the FSM for zxt there is tests you can do for:

COIL
CAS

IGNITER (transistor)

You can try to the PRW2 ignitor from later Nissans they are plentiful. There is a writeup on that somewhere.

 

"Now i had this engine running 4 years ago although not very well I think it was low spark from the old coil."

 

This all to familiar to me. Honestly, do yourself a favor and get rid of the stock 82/83zxt ECCS system they are very troublesome. You can get a 300zx ECU/MAF for cheap or ms2 system (we do offer a plug and play complete system) I went through the same thing 15 years ago trying to diagnose, trouble shoot and crap shoot everything. Even when it ran would sputter and backfire. Ahh good memories........

 

Also did you verify with multimeter while IGNITION ON and RUN something easy overlooked. You also mentioned you get a spark jump while you turn on ignition on that is very strange.

 

 

Edited by softopz
extra help

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1 hour ago, softopz said:

 

This all to familiar to me. Honestly, do yourself a favor and get rid of the stock 82/83zxt ECCS system they are very troublesome. 

 

 

Yup... Chances are you'll need to get to a different engine management system at some point. Read my posts over the last 9 or 10 years and you'll see what we mean. I struggled with the stock ECCS for years before I decided to change. I started with an Infiniti M30 ECU swap with Nistune (much the same as a 300ZX only Infiniti - so, better - and my son's '76 280Z L28ET still runs well on the Infiniti ECU (also there used to be a bunch of M30's in the yards here in Phoenix - not anymore...). I tried a VE30DE ECU for COP at one time and ended up with an MS3X. There are any number of good options out there these days for stand-alone ECU's however.

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I went through the same struggle for a number of years too!! Thats why I mentioned MS2 ironically we now are a dealer for Megasquirt and offer a turn key package. That includes Pre-configured ECU, plug and play terminated harness + fusebox/sensors/

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