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NC280z

Another ZX distributor question

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Good evening all,

 

I've ran into a bit of an issue with my ZX distributor swap. The car will start fine but once it's warmed up it will hesitate/buck and misfire while the rpms increase up to and beyond 1400 rpms. I have the initial timing set at 8 btdc, and I've even tried disconnecting and plugging the vac advance and it will still hesitate and misfire if the engine temp is at the halfway mark. After some research I've found that the distributor Rock Auto sent me is from an '82 ZX (stamped D6k81-01), and it provides the highest total advance out of the matchbox dizzys.

 

I've swapped back to my working Federal dual-pickup distributor, I'm just hoping someone could provide some ideas as to why I'd have a part-throttle misfire after warmup with the ZX distributor, and not with the '75s stock distributor. I should note that I'm running an n42/n42 setup with flattop pistons, so the compression is a bit higher than on the later ZX engines.

Edited by NC280z

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What have you swapped this distributor onto? an earlier 280z???

 

 

By ZX distributor you mean the matchbox one used on the non turbo engine?

 

The one with the E12 93 matchbox module? This one...?

3h6NWI6.jpg

 

 

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I apologize for not fully describing the setup. I've put the distributor on my 1975 280z, and it's a reman distributor with the generic (no-name manufacturer) 2 prong e12-80 module. 

Edited by NC280z

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Not familiar with the early EFI distributors. They were EI weren't they? Had two pick up coils? This was a remote igniter system?

 

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The original distributor is EI, and it has two pickup coils.  The ignition transistor is remotely mounted in the passenger footwell. The original setup runs fine but I've read that the ZX setup is a worthwhile upgrade

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I can't see why if they are both EI. The remote igniter on the '78 Datsuns is the same as the later matchbox.

 

Are you disconnecting the remote boxes completely? The matchbox and the coil run on straight 12 v....  Can you measure the coil resistance? An EI coil should be 0.8 to 1.0 ohms and not need a ballast resistor.

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From what I've read, the matchbox distributor sends a hotter, more consistent spark when compared to the earlier EI system, which is why people will upgrade to the matchbox distributor on their 75-78 Z cars. When I installed the ZX distributor I removed the remote igniter and the ballast resistor (http://www.atlanticz.ca/zclub/techtips/distributor/index.html).  I've tested the MSD blaster coil I'm using and both the primary and secondary resistance readings are within spec.

 

A better description of what's occuring is that it almost sounds/feels like a rev limiter/cutout is occurring with the ZX distributor when the engine reaches operating temps. 

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This is why I asked what matchbox you are using. The E12 80 does not have ignition retard and you need the EFI box to work it anyway. If you run an E12 93 module it will introduce ignition retard as it's revved up.

 

Within speck is meaningless is it 1.0 ohms or just under? If not sure dump it and get an EI coil from a '79 200sx. I don't believe in after market wizz-bang coils and only trust the factory equipment designed to work with other factory equipment. 

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So I had a dyslexic moment today, the distributor I received from Rock Auto has the 4 prong e12-93 ignition module, not the 2 prong e12-80. By EFI box do you mean the L-Jetronic ECU? I've kept the L-Jetronic on my '75 Z and it's all stock. I would imagine that the e12-93 module would be the one that needs a specific ECU because my understanding now is that the "I" and "W" connections go to some sort of knock sensor. Am I correct in this? The 2 prong e12-80 module came on the earlier ZXs (79-80/81) which had an ECU similar to the 75-78s. 

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The 280z was never designed for working the ignition retard. This is a zx thing.  You could mess around grounding one or both side terminals and see if that fixes your timing curve. I heard this will work but I don't know which ones.

 

E12 80 module (the simple one)

f6MEqUf.jpg

 

 

E12 93 module (the complicated one)

PXHdjNk.jpg

 

 

 

 

Get an E12-80 matchbox module and all will be ok.

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