87 Testarossa - Has No ignition to spark plugs - *Both Banks* Need assistance please?

Not sure that you are understanding what is needed here -- each wire (the green and the yellow) needs to have its own "shield" fully surrounding it and acting as the second wire for each sensor (not "for 2 wires"). What I don't like about this zippertubing product is how to connect the short wires at each end -- conductive epoxy is not near as reliable as a soldered joint. My choice would be to put a small solderable ground braided wire around each of the green and yellow wire individually so that the short wires at each end can be soldered to it, and then you could put the zippertubing product over each one of those individually for a little extra EMI insurance and to insulate them from each other. Then, finally, something to go over both to make a single "cable". JMO (although there may be other ways to skin this cat).

 

yes, this I mean. and even the inner wire is multi-core, so flexible

 

You're right, I didn't fully understand this. Ok, so the green and yellow wires need to be shielded and that means as tightly as possible, e.g., not putting 2 insulated wires inside the shrink, the yellow/green must be shielded individually. It seems like the least complicated would be to try to replicate the factory shielding, e.g., wrap the black copper wire around the yellow and the blue copper wire around the green, leaving the insulation at the ends for the connectors and then shrinkwrapping each set of wires (green/blue and yellow/black) as a pair.

As for this suggestion: "my choice would be to put a small solderable ground braided wire around each of the green and yellow wire individually so that the short wires at each end can be soldered to it, and then you could put the zippertubing product over each one of those individually for a little extra EMI insurance and to insulate them from each other" - what would that look like?

Thanks again for the education here, this is why you and this forum are such a great resources.

Todd

 

You need a short section of "regular" wire at each end of the shields to attach to the second terminal of the connectors (as you mentioned in post #19). What I meant to apply the zippertubing over each of the braided shields was to act as insulation so the two braided shields don't touch each other when they are finally combined into a single cable (as well as being more EMI protection for each -- shrinking the zippertubing pieces over each of the braided shields should good electrical contact between the foil in the zippertubing ID and the braided shield OD).

 

I’ve been communicating with Todd as I also am in need of a repair on this harness. Todd simply ran new black green yellow and blue wires and used shielded shrink wrap on the yellow wire in the yellow/black pair then the green wire on the green/blue pair and crimped new connectors in place. Steve what would you do?

Thanks - Jeff

 

Ummmm...that's not quite the same thing physically. One shield (covering the yellow and black wires) should be electrically-connected to the black wire (at both ends), and the other shield (covering the green and blue wires) should be electrically-connected to the blue wire (at both ends) to be similar to the stock wiring arrangement. Might be OKish just having "floating" metal shields (if Todd's system is working well). The bottom line would be to look at the "quality" of the TDC and RPM signals at the Microplex ECU (with an oscilloscope) during engine operation and see if any significant spark ignition noise pulses are getting into those signals or not.

 

Hi - its slightly different. I have the single yellow wire shielded with the zipper tubing, then the black wire is within a second shielded tubing that covers both the already shielded yellow wire. Same with the green wire. Here's a pic I sent to Jeff where he circled the two different shieldings. I was unable to recreate the factory setup and be confident that I'd be able to wrap the bare copper tight enough and not miss any spots and then get a solid crimp on a connector which would be adequately sealed from the elements. Maybe someone has a technique they could share. The OE PVC covered wires (yellow and green) on the OE harness were cracking due to heat and age and they had to be replaced.

I should look at the signal, though, to see how it looks.

Image Unavailable, Please Login

 

Yes, that is a little different configuration, but two floating shields shouldn't be worse than one floating shield. If your system is working well, it probably is OK. Ferrari's choice makes sense for them as one wire and one shield for each sensor is the minimum weight/cost, but can't fault your choice.