mx5cartalk.com

Looks like another gremlin has been found...

The wiring to the COPS (#4) has broken. Not sure how long it has been like this, but may explain why the 'miss' sometimes shows itself. After starting the car yesterday it was running a little rough, just like it did at WTAC so checked the COPS and #4 was not 'firing'. Went to replace the COP and noticed the broken wire, turned the plug and the second wire 'broke'

The bad news is I do not have the wiring diagram that was done with the car, plus it does not match the standard PS1000 wiring

A few hopeful questions

1. Can I guess which wire goes into the plug? Zooming in the colour of the wire can still be seen
2. Should I get a multi-meter out and track down each wire?

#4 (broken)




#1


#2


#3

From your first picture, left to right:

12
Tacho
Ecu to coil trigger
Ground

So your power is ok, and the next wire to the right is the broken one which has continuity with the other 3 wires at position 2 looking at the plug from that angle, and the last wire goes to the last spot.

Dann

NitroDann wrote:From your first picture, left to right:

12
Tacho
Ecu to coil trigger
Ground

So your power is ok, and the next wire to the right is the broken one which has continuity with the other 3 wires at position 2 looking at the plug from that angle, and the last wire goes to the last spot.

Dann

Thanks

You can see enough remaining in the socket to work out which goes where.

From the left in pic 1;
Black with white stripe > Blue with yellow stripe > White> White with black stripe

Yep, noticed the little bit of colour left in the plug.

Been given a fix as well, similar to the CAS fix, pot the connections. Rough cost about $500 but will have stuff left over for the rest of the wiring job. Potting the COP’s will solve the problem, it seems to be common.

https://m.facebook.com/story.php?story_fbid=1879384248820353&id=157944390964356&ref=bookmarks&notif_t=feed_comment

The racecar ran Toyota COPS with Toyota plugs for years, without a problem. Maybe not as often as you run your car though ...

It might be worth looking at whether you can better secure the wiring to reduce movement with respect to the plug, as potting may otherwise only change the location of the failure point.

greenMachine wrote:It might be worth looking at whether you can better secure the wiring to reduce movement with respect to the plug, as potting may otherwise only change the location of the failure point.

The wire does feel a little brittle, reviewing the data over 4 years shows the miss decreasing in frequency and severity as each problem was fixed.

CAS sensor,fuel pressure and alternator fixes have all reduced the miss but never eliminated it. Maybe it is time to replace the wires as well as protect it from vibration and heat. Since potting the CAS never had an issue with it. If the COP is potted, Ike the CAS keeping a flying lead or 2 will allow a replacement to be put in quickly. The potted COP will have a short lead with a Deutsche plug to join 8nto the main loom.

Anyway this would be the start of the loom for the shell

OK, I misunderstood. I thought you were potting the plug/connector. You can do the COPs for sure, but I would try replacing the wiring on the plugs first, making sure that the wires are no thicker than necessary, and that they are supported to minimise movement. If the plugs are not Toyota OEM, I'd replace them too - those ones of yours look like they have seen a bit of service.

If you pot the COPs, do a spare or two - they do fail, and having a spare will keep you on the track.

I think potting them is a bit overkill to be honest.
Yeah, it'll solve your issue, but I don't think you require anything more then just a well made loom. I am using the same loom since my red car and it's fine, and I do easily as many hours racing as you do, And it's a piece of sh*t, but I used good wire and got the lengths a little on the long side.
Being able to easily disconnect one or more plugs is a great tool for troubleshooting, you wont be able to do this with potted COPs, unless you have a individual connector for each COP...

Just getting some good wire, ensuring you have good crimps, have the lengths right with a little strain relief will solve your issue, and give you a reliable loom for the future.

Remember

KISS

Also, the wiring looks like it's using standard wires from an mx5 loom, can you confirm? Is it wiring from the NA6 originally?

Will check on the wire. I suspect OEM wires.

I have a spare set of COP’s so can make up a new look. Am ordering connectors and wire today.

Plug acquired and spliced in. Found what I expected when I opened the loom up

Interestingly #4 cop was diagnosed as being burnt out in 03/16 and replaced.

As an NC1 owner I sympathise with you

Happy New Year

Temp fix done, wreckers $10 for a plug. Was going to get the other plugs, but they had the tabs broken off

Looks like it was the signal wire, and has been for a while.


Hmm, not surprised

I ordered a set from these guys.

https://www.bmotorsports.com/shop/static.php/post/miata

Custardtart wrote:I ordered a set from these guys.

https://www.bmotorsports.com/shop/static.php/post/miata

I’m waiting for Ballenger to finish the design on some boots that will give some strain relief and protection to the wires.

Time to start the purchasing of stuff to rewire the car.