Car wont start after ECU swap.

Nissan 300ZX technical discussion forum: Maintenance, performance, installations, modifications, how-to's and troubleshooting.
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Retro-Cow
Posts: 76
Joined: Fri Sep 21, 2012 10:48 am
Car: 1993 300zx TT
Location: Salt Lake City, Utah

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So I just completed a plenum pull, 300 degree fuel rail install and nismo 740cc injectors. I also installed an Ash spec ECU but the coil packs dont get power.
It's getting fuel and air perfectly fine.
It also sparks and starts fine with the stock ECU but obviously runs rich.

Some info about the car that may help in determining the problem, it started as an automatic and I did a 5 speed swap on it. I used the "conversion" harness from z1 and I didn't wire the clutch to anything and I bypassed the starter relay. This may have something to do with it?

Any help would be greatly appreciated.


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Retro-Cow
Posts: 76
Joined: Fri Sep 21, 2012 10:48 am
Car: 1993 300zx TT
Location: Salt Lake City, Utah

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Oh forgot to mention that the Ash spec ECU is a manual ECU.
It starts fine with the stock Automatic ECU.

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Retro-Cow
Posts: 76
Joined: Fri Sep 21, 2012 10:48 am
Car: 1993 300zx TT
Location: Salt Lake City, Utah

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So I got her to start and run by removing the green ignition relay in the relay box and just connecting the points with wire.
Any ideas on why the stock ECU would power that relay but the new tuned one won't? Also it is safe to run with that connection bypassed like that?
To specify this is the relay in the engine bay not the starter relay.

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t.mcginley.jr
Posts: 1547
Joined: Fri Jun 01, 2012 5:50 am
Car: 2002 Nissan Altima SE 3.5
1990 Nissan 300ZX NA 2+0
1966 Ford Mustang
Location: New Jersey, USA

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Are you sure the relay isn't just bad? You can test by swapping in a known working relay like headlights, horn, etc.

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Retro-Cow
Posts: 76
Joined: Fri Sep 21, 2012 10:48 am
Car: 1993 300zx TT
Location: Salt Lake City, Utah

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The relay is fine. I already tried switching it with another and if the relay was bad the car wouldn't start with the stock ECU either.


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