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Need help z31 ECU Swap + 280zx Turbo swap into '77 280z


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I've been working at this electrical swap for the past week. I have followed every possible guide you can find online, and those that aren't available anymore.

 

I have three z31 turbo ecus (88'x2 and 87'x1)

 

No matter what I do, I have not been able to even get the ECU's green light to come on. I've opened up all three ecu's and there are no burn marks anywhere. They all look very clean.

 

I'll add some photos here of my harness. If someone can tell me where it is I'm going wrong or how to exactly wire this, I would greatly appreciate it.

 

this is the whole harness. I do not know what year it is, but I believe it to be 82-83 because it has 8 pin connectors, and not 6 pin.

https://www.dropbox.com/s/yuig448fpd7fsm7/IMG_20130414_000623.jpg

 

this is right near the ECU connectors.

https://www.dropbox.com/s/yvgblp0ps8ek9cq/IMG_20130414_000733.jpg

 

here are the connectors

https://www.dropbox.com/s/w2bil80b5bi1zop/IMG_20130414_000713.jpg

 

this is the CHTS and knock sensor plugs

https://www.dropbox.com/s/u66z6g10epxx4ti/IMG_20130414_000629.jpg

 

here is near the relay

https://www.dropbox.com/s/tnvb4jcje3zr0f1/IMG_20130414_000654.jpg

 

======================================

 

here are the guides i've been following

 

CygnusX1's diagram

http://gyazo.com/0869d6211e5c73253691fed364532a5b.png?1365923974

 

1. http://forums.hybridz.org/topic/38416-82-ecuwiring-harness-install-in-1977-280z/

2. http://forums.hybridz.org/topic/34469-a-quick-fi-and-ignition-280zxt-to-s30-turbo-swap-guide

3. http://www.zcar.com/forum/10-70-83-tech-discussion-forum/111562-turbo-swap-wiring-harness-q-2-a.html

4. http://forums.hybridz.org/topic/100535-83-l28et-harness-into-24z/

5. http://www.xenonz31.com/s130/Z31MASin280zxt.html

 

I'm not sure what I'm doing wrong at this point.

 

Also, what pins on the ECU need ground and power to turn it on?

Edited by Milenko2121
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Looks like you were almost where you needed to be to answer the last question.  Or at least tell you which pins have power and which ground.  Probably paged right over it.  There are other pin-outs shown, like EFEC 84 for the CAS.  That's where I'd be if was in your shoes.

 

http://www.xenonz31.com/reference.html

 

Attached a sample.

post-8864-0-31373900-1365959453_thumb.jpg

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Got it.

 

I had the wrong Plug #1

 

the previous owner cut up the harness and spliced in 2 blue wires instead of the Brown/Green wires.

 

I didn't fire the engine, I just provided the 12v and ground, and bam the ECU light went on.

 

I'm going to finish it up tonight. This is exciting, and was so frustrating.

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ok well here is how I have it wired currently, if someone could help me i'd really appreciate it.

 

Plug #1

Brown to + Battery

Green to + Battery

 

Plug #2

Y/W to - Coil

G/L to ground

Y to 12v start + Y/W from ignition harness

 

Plug #3

B/W to 12v switched

G to 12v switched

 

and for the ignition harness

 

I have

Y going to Y/W from Plug #2 + 12v start

B/W going to 12v switch

 

Can someone tell me why I'm not getting spark(coil isn't grounding out)

and why are my injectors not firing?

 

I thought this would be way less hassle than this. All these guides seemed so easy, but when I wire it how they say, it isn't workin.

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Pretty sure both of those rely on the CAS signal.  The ECU (ECM) gets the CAS "triggers" (more than one maybe) and causes the power transistor (ignitor) to cut current to the coil to cause spark, and grounds the injectors to cause squirt.  Different times of course.

 

Have you gone through the troubleshooting procedures in the FSM?  Once you're wired in, you essentially have an 87 or 88 ZX, just 280 intead of 300.  Code 21 is on page 93.  Even tells how to check the power transistor.

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Page 93 says "CHECK GROUND CIRCUIT".  If you're getting ignition pulse and the ECU isn't using it, maybe the ECU is bad.  But you've tried three so that's unlikely.  I'm guessing that your CAS isn't right.  How did you measure "ignition pulse"?  Did you use a "logic probe"?  Or did you just measure voltage?  You have to have the pulse.

 

That's all I know.  I would study the FSM.  Inputs > ECU > outputs. 

 

Somebody will probably have some ideas if you show what and how you measured and the numbers you got.

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The power transistor (also called an "ignitor") controls current to the coil, and the transistor is controlled by the ECU.  The 280ZXT transistor is out in the open on the coil bracket and looks like a quarter-sized metal object.  The 300ZX transistor seems to be a little more hidden but still looks the same.  There's a drawing of all of the parts on page EFEC-4.  It's shown under the coil.

 

The transistor does essentailly the same thing that the ignition module used to do on your 77's original system.  Except that "dwell" control is handled by the ECU in the 300ZX ECCS, where it's handled by the module in the 77 system.

 

If you don't have a transistor the ECU can't control the coil.  The transistor is supposed to be at the end of one the wires in your wiring instructions.  Page EFEC-13 shows the factory wiring to the coil, and how the L (blue) wire connects from the coil negative to the transistor (that's where it controls the coil ground).  They do go bad sometimes, apparently, especially if not grounded correctly.

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https://www.dropbox.com/s/8bbdhq3tzyftrdy/IMG_20130415_000312.jpg

 

here is the cabin side of my ignition harness. the person i bought it from had cut it at this end.

 

I'm very certain i'm at the point where it's my ignition harness wiring that is at fault. everything else works as far as I can tell.

 

I'm at a loss as to how to wire it considering my current setup isn't working.

 

and I tested the transistor, and test showed it was fine.

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still no luck.

 

Coil/Bracket are mounted directly to car where stock coil used to be.

Condenser is mounted to bracket, and B/W hooked into it.

 

on power transistor, B/W is going to ignition on, Y/W goes to pin 5.

 

on ECU pin 34 is going to + side of coil.

 

is there something I am missing?

 

=======================

 

I'm getting pulse to Y/W on Pin 5, and 12v to B/W

 

===========================

 

Just tested the power transistor in diode mode.

 

I'm getting continuity no matter the polarity. This means a bad power transistor correct?

Edited by Milenko2121
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still no luck.

 

Coil/Bracket are mounted directly to car where stock coil used to be.

Condenser is mounted to bracket, and B/W hooked into it.

 

on power transistor, B/W is going to ignition on, Y/W goes to pin 5.

 

on ECU pin 34 is going to + side of coil.

 

is there something I am missing?

I know you said you tested your power transistor (igniter) and it was good, but I'm still gonna throw it out there that maybe it IS your problem, it does happen. I know you had the swap running before the Z31 ECU swap, but was it on just your 77 ECU?

Point being that I didn't know there was an igniter checking method, and when I deemed my 280zx ignitor was bad, I just did the GM HEI ignition module swap-a-roo, and fired the motor right up. It's less than a $25 swap/test, could be that simple.

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SHE LIVES!

 

Replaced the 280xzt coil and ignitor with a z31 coil and ignitor i got from the junkyard, and she fired right up.

 

Just got everything routed into the car, and I need to go buy an o2 sensor, haha.

 

One weird thing currently though. When I tried to set timing with my old school timing light, the Timing mark keeps moving counter clockwise at a consistent pace.

Edited by Milenko2121
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