A little history on m car... I purchased this car 3 months ago and it came with the KD rotary anti-det mod done. This means the car is setup to run without the trailing plugs. Tonight I was installing the leading coil pack (even though it uses leading plugs it fires off of trailing coils) back into the car, so I could undo the mod in the future when I can have it tuned by a pro.

I was unplugging the coils to make room and black tape started peeling off....So curiousity mode kicked in and I started undoing all the black tape. Here is what my harness looks like without all the tape:





So I can't imagine it came from mazda like that.

 

Im no expert on this. But i think that looks fine. I have not taken apart my ign coil harness, but i did take apart my engine harness. The blue tape is common among the wiring in the FD. Mazda liked it, and used it all over the car. :? To me though, that all looks like the stock unmodified ign coil harness.

Please take this with a grain of salt until someone who knows more then i do regarding this chimes in.

 

Normal; those are the ground connections to the wire shielding. Clean up and retape with the correct harness tape. Be sure to reconnect the shields to ground.

 

Ive seen worse

 

FYI, that is the original ignition harness, it's not the updated one that Mazda has now. The old one has the ground wire that connects to one of the coil packs, the new design doesn't.

If you're in there replacing parts, go ahead and buy a new harness with the updated design. The old ones are prone to have misfire problems and ignition breakup at high RPM.

Dale

 

Hrm, I wonder if this is part of the problem I've been having. Looking for a new design now.

Thanks!

 

Both the ignition harness and main engine harness should be replaced if both are the original bad ones, and you are doing any major engine work. The first design had used inferior wiring which was very prone to insulation cracking and becoming brittle, and the copper wire oxidating.

My replacement ones which were installed in 1999 (11 years old now) are in so much better condition than the originals were when replaced at age 7 years.

 

When were the ignition and engine harnesses updated? Ours is a '94 built in Nov. '93.

 

I am planning on replacing the main wiring harness when I go single turbo.

 

Hi everyone,

My car usually idles flawlessly. Sometimes, seemingly randomly, it starts missing. I'll start the car an hour later and it's back to normal. Also, I have high RPM breakup now and then.

I picked up a new, sealed-in-the-Mazda-bag coil harness for about 50% of the dealers (Malloy's) in the for sale section of this forum. Given the price (lucky find), this is as good a place as any to start troubleshooting the problem. Besides the old harness is crispy and needs to be replaced anyway.

The old harness has the ground strap and the new one does not. I was going to ask why but this forum seems to have all of the answers after 10+ years. I shot a pic and thought that this would be a good thread to add it to.

James

 

That's just how they did the new harness with no ground strap. Seems like the ground would be better but I guess it wasn't needed.

I've seen quite a few cars with weird ignition problems that a new ignition harness fixed.

Dale

 

At this stage in the game, anyone still running their original ignition harness should definitely consider replacing it with a brand new one

 

Yup, $80 from Ray at Malloy Mazda.

 

Weird; I would have thought the single eneded ground of the braided cover would have been required to keep EMF out of the low voltage triggering signal. Maybe they grounded internal within the plug ground??

 

^Bingo.

 

Anyone know the part number for the new engine harness?

 

From the pic above, looks like the new number is N3A3-18-05Z (?), but not sure of the number in parenthesis. I think it's Illustration No. 2 in the 1994 RX-7 parts catalog picture attached.

 

Enlarging the photo clearly indicates N3A3-18-05Z (3), I don't recall seeing a PN descrption that way before??

The N3A1-18-... part is the main engine harness (Illustration #1) for Manual Trans cars; where-as N3A2-18-... is for automatic. N3A3-18-... is the Illustration #2 harness (coils)

N3A1-18-05ZF is an acceptable alternative to N3A1-10-05ZE

and N3A1-18-05ZH is and alternative to N3A1-10-05ZG

 

^ +1. Also there is a VIN break for some of those P/Ns at ... 4408, for the 1994 model.

 

Yes the VIN is a break point, but then the 'A" fro alternative is given for the higher revision letter, so should be Ok.

 

.

 

Yes, but what is pictured is the ignition harness, not the engine harness. I'm assuming the engine harness is the one that contains the solenoid connectors and routes underneath the UIM, right?

 

dblboinger,

True. But thought only the ignition harness had changed. In any case, the correct engine harness numbers (for 1994 models) are shown both in my attachment above, and also are listed correctly by Julian in post #18 above.

 

I've never torn into an FD harness, and hope I never have to, but going from my experience with the harness on my REPU, and looking at the pictures shown here, Mazda uses blue tape to mark splices.