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Is ECU wiring loom lenght important?

Posted: Tue Dec 26, 2017 6:04 am
by GGR
Hi All,

I have a project where I am fitting a Mercedes M120 V12 out of '93 600SL into a '62 W111 Coupe. I would like to keep the original engine management system for now (2 ECUs - one per cylinder bank - and one ECU for electronic throttle actuation) and look into Megasquirt later, when I have worked out a new intake system and camshafts. I would like however to fit the ECUs in the trunk, together with the battery. That would mean lenghtening the original wiring loom. Will the lenght of the loom affect the nature or quality of the signals from the sensors? I guess Megasquirt versatility can compensate for this, but how will a stock system react to an additional 6 feet of wiring?

Thanks for the help, and Merry Christmas!

Re: Is ECU wiring loom lenght important?

Posted: Tue Dec 26, 2017 9:20 am
by jsmcortina
Greater cable length will have at least two effects.
1. voltage drop on high current signals
2. risk of noise pickup

James

Re: Is ECU wiring loom lenght important?

Posted: Tue Dec 26, 2017 10:08 am
by GGR
Thanks!

How would that translate in real life? Would that really impact how the car runs, or would the effect be marginal?

Re: Is ECU wiring loom lenght important?

Posted: Wed Dec 27, 2017 3:11 pm
by Matt Cramer
I've seen an industrial installation where they put the ECU about 50 feet from the engine... and the engine itself was somewhat larger than a Mercedes W111. Not larger than the engine in a Mercedes... larger than the car itself. They didn't have any problems.

Re: Is ECU wiring loom lenght important?

Posted: Thu Dec 28, 2017 6:03 am
by Paul_VR6
As long as everything is grounded and shielded well, I don't see an issue.