HELP! Mallory Distributor ( 4563901) on 280ZX wiring

[Mr240GT]

hi all, i replaced the stock 280zx distributor by ( Mallory ) p/n 4563901. after connecting wires the car wont start. i noticed there is a spark going to the plugs but no signal going to the injectors!!! any help , drwaing, appreciated.

note, mallory wires ( red - green- brown) , the brown wire lookl ike the ground. do i need to put adapter in between the mallory and the coil?? i heared the GM adapter is ok !! is this true

please help

payusup@hotmail.com

thx

Edited October 17, 2015 by Mr240GT

[Zed Head]

What year is the car?  And which country did it come from?

 

You said 280ZX distributor, but you may not have a ZX.  Typicality though, there's a blue wire that would be attached to the coil negative terminal that goes back to the tachometer and the ECU.  That's what the ECU uses to know when to fire the injectors.  Does the tachometer still work?

 

And you siad that you see spark, but you didn't say when.  You can see spark when you turn the key on and off, but still not have spark when the engine is cranking.  Describe how you tested for spark and how you know that you don't have injection.

 

Here is a link to many different manuals and diagrams.

 

http://www.classiczcars.com/files/

[Chickenman]

He's using a Mallory Optical distributor in place of the 280ZX distributor.

 

OP: Do you have a normally aspirated 280ZX or a factory Turbo 280ZX . I'm assuming a 280ZX of some sort as this post is in the ZX forum.

 

The Mallory distributor is designed for a carburated car, it will not work on the stock Nissan ECU. The Optical sensor on the Mallory sends out a different signal type ( square wave ) vs the Variable Reluctor of the stock Nissan dizzy, which sends out a Sine Wave.

 

The ECU receives the Injector trigger signal from the dizzy, but with the Mallory Optical ignition the ECU can not understand the signal pulse.

 

Note: This only applies to the Normally aspirated 280ZX. The 82 and 83 280ZX Turbo's also use an Optical distributor and the ECU should be able to trigger the Fuel Injectors from the Mallory.

 

You may be able to install a Tach adapter to convert the signal into something the Nissan ECU will understand, but more research will be needed.

 

From MotorSport Auto:

 

 

Restrictions:
Mallory Unilite distributors will not work with the stock Nissan fuel injection system ECU. If you are running carburetors on your 75 & Later L-Series engine, this distributor can work. If you are running an aftermarket fuel injection system that does not utilize the factory ECU, please check with that product's manufacturer for compatibility with a Mallory Unilite.

 

http://www.thezstore.com/page/TZS/PROD/12-4042

Edited October 18, 2015 by Chickenman

[Zed Head]

That's interesting from MSA, but the explanation doesn't quite fit.  The ECU doesn't see the distributor trigger mechanism, just the make and break of the coil current, on the negative post.  They're different sides of the ignition module.

 

So the problem would be more about the ignition module side of the Unilite.  Maybe it doesn't cut it cleanly, so the ECU doesn't get a good sharp signal.  Interesting issue.  I wonder if a GM HEI module in between could "translate" the Unilite weirdness.  Use the Unilite to run a GM HEI module, just like using the ECCS to do the same.

[Zed Head]

Back when I had stock ignition components I found that the ECU would not fire the injectors if the resistor on the tachometer line was not in place.  So the ECU is sensitive to the quality of what is coming through on the blue wire from the coil negative.

 

I wonder if there's a combination of coil and Unilite that would work.  It seems like I've seen people with 280Z EFI use the Unilite.  I'll have to do some Googling.  Maybe it's stock coil + Unilite + EFI that doesn't work.

[Chickenman]

We'd have to dig deeper into the wiring diagrams of the factory ECU and the Trignition boxes/ Modules on 280Z's and 280ZX's. But a quick Google search shows many people that have had problems running the Mallory Unilite on the factory FI system. None were able to make the Fuel Injectors fire. Some of the threads you answered but I couldn't find any that were resolved. Mind you I haven't searched that long....

 

I think that you're right that it's a signal type or strength issue.  Bottom line is that the ECU is not getting an RPM signal or it is getting one that it can't understand with the Mallory, so injectors do not fire.

 

OP: Is your car a 280Z or a ZX? Totally different Ignition circuit wiring on them and we need to know more of what you've done.

Edited October 18, 2015 by Chickenman

[Chickenman]

Could probably be made to work... but is it worth the trouble? Most people seemed to go back to the stock ZX ignition. Actually, on a 280ZX... why would you get rid of the factory " Matchbox dizzy " in the first place?

Edited October 18, 2015 by Chickenman