[Diy_efi] Wires broken inside insulation

[Mike Frels]

These last couple of posts have been some good food for thought. The 21 year old emissions/control harness in my car mught be contributing to some of the puzzling ways my engine seems to change temperament day to day and season to season. Here in the Gulf Coast of Texas, USA we see some pretty wide humidity swings. It can range from 10% sometimes during the winter months to 90-100% during the summer. Most of the time I attribute the performance change(butt dyno of course) to changes in barometric pressure but I was never really convinced. Could it possibly be changes in conductivity due to changes in the moisture level of the air? Sounds like it might be a good idea to pull the complete harness and do a complete inspection and rebuild.

Thanks for all the technical input on the corrosion mechanisms.

Mike


-----Original Message-----
>From: Mike <niche at iinet.net.au>
>Sent: Mar 30, 2007 2:43 AM
>To: diy_efi at diy-efi.org
>Subject: Re: [Diy_efi] Wires broken inside insulation
>
>At 01:43 PM 3/30/07, you wrote:
>>That's good to hear, Mike, thanks. Or is it bad news?  Glad I havn't run into more of it, heh.
>>Ernie 
>
>mmm, Now that I think of it, the other likely failure mechanism relates to where the loom
>is bundled and compressed where it passes through the firewall. On my model, there is a bunch
>of wires from the various EFI sensors as well as drive lines to the injectors all bundled together
>and about 150 to 200mm from the exhaust manifold and turbo. So on hard runs the hot air
>from that is always passing over this tight bundle, imaging that the PVC breaks down and
>thin cracks start to appear, then imagine the first rains and puddles throw up water and
>it seeps its way into the cracks.
>
>One wonders if this might allow the pulses and back emf from the injectors to find a path
>to the analog sensor cables, especially if the copper chloride/copper sulphate as a result
>of corrosion is moistened,
>
>This might well explain odd things my ECU does as it sometimes acts as if the AFM is
>out of whack, ie Trips the ECU to overfuel - which is a common issue with the Bosch/Hitachi
>ECU on a 20 year old car, <sigh>
>
>
>
>
>Regards from
>
>
>Mike
>Perth, Western Australia
>VK/VL Commodore Fuse Rail panel that wont warp, twist or melt, guaranteed  !
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>http://niche.iinet.net.au