Engine ECU wiring

[andyborris]

I'm installing a modern (ish) engine into a 1960's car, this engine has injection and a ECU.

I'd like to place the ECU in the cabin, this means cutting the wiring loom to route it through the bulkhead. It also needs a lot of redundant wiring removed.

Several of the sensors on the engine have shielded wiring, when I cut and then rejoin these wires, they may be a gap in the shielding.

My question. Are these wires shielded because the static they produce will affect the good running of the engine, may scramble the ECU, or just stop me tuning into the Archers?

The first two are a worry, I can live without the Archers.

[RobinJI]

It's the first 2 unfortunately, or well, pretty much only the first. It can be helped by wrapping paired wires in a spiral, but shielding them's a much better solution. Having a small gap in the shielding won't necessarily be the end of the world as long as it's no where near anything producing large voltages/currents (keep it away from other wiring, in particular HT leads, coils, starter wiring etc..) But the shielding its self will usually only be earthed at one end, so if you cut it and don't re-join it then it will only be shielded on the side of the cut that's earthed. It may be better to replace the entire wire with a new shielded one.

I'm surprised you're having to cut the loom to pass it through the bulkhead though, maybe you could do something like classic minis have where there's a large hole that it's passed through, and then a closing panel fills the hole back down to a sensible size.

[andyborris]

Thanks, unfortunately the ECU plug is huge and I'm not keen on cutting such a large hole in the bulkhead. I'm trying to keep this engine swap as un-intrusive as possible

So, you're saying that the shielding is there to protect the signal? Can I add shielding?

[andyborris]

Perhaps something like this, www.kemtron.co.uk/products/emc/cable-shielding-jackets.html I was going to use cable protection anyway, looks expensive though!

[Clamity]

That product would work, but as you say it looks expensive. Perhaps copper sticky tape around the individual wires followed by pvc tube, or loom tape or whatever you want to use as an outer cover would be a cheaper solution. You want to avoid it coming into contact with bodywork (or any exposed live wires) as RobinJI says, the shielding is deliberately only connected at one end to avoid any ground loops messing up the electronics.

Could you not keep the ECU in the engine bay but box it in somehow instead?

[andyborris]

Engine bay is a bit crowded now and I'm worried about heat damaging the ECU.

I've had a rethink, all the wires are much longer than they need to be, so perhaps I can "peel" the shielding away from the core, shorten the core and then overlap the shielding in the joint, with maybe a glue shrink tube around it.

Provided the shielding makes a good contact in the joint, it'll still work, won't it?

[skip0pot2mus]

Can't you de-pin the connector?!

[Rev. Dick Deluxe]

Yes. Much easier to take the wires out of the multi plug and put them back in after than cutting a complete loom and re joining it.

[andyborris]

Thanks skip0pot2mus, didn't think of that.

And Rev. Dick Deluxe, can you say a small prayer for me......please.