[Diy_efi] Welding on cars w/ ECU's??

[Programmer]

It's probably not big cap inside--they just made the pig rather large. Has
battery clamps and a whizzy little light to show it's got a good connection.

Lyndon

----- Original Message -----
From: "Chris McKinnon" <chrism at cnx.net>
To: "List for general do-it-yourself EFI talk" <diy_efi at diy-efi.org>
Sent: Friday, January 31, 2003 3:56 PM
Subject: Re: [Diy_efi] Welding on cars w/ ECU's??


> Wouldn't you want a smaller, faster cap like a metalized poly EMI
supression
> cap across the battery? The battery is already a cap with it's parallel
> plates and electrolite  but it's more like an electrolytic cap which has
> poor transient response... Right?
>
> Chris
>
> >Easiest answer is that it probably started from the autobody industry. Hi
> >frequency machines "theoretically" could induce voltages into the PCM
(some
> >are mounted lower left/right fender, others at the frame horn, etc...)
and
> >fry the chips--I've never had or have seen this problem,  but you never
know
> >when some "welder" is going to put the ground clamp onto a PCM / ECM
case,
> >"someday". We do have a giant capacitor that we install across the
battery
> >terminals when doing any weld repairs--just in case.
> >
> >Lyndon ; )
> >
> >----- Original Message -----
> >From: "Chris Spies, ATI ProCharger" <proddev at procharger.com>
> >To: <diy_efi at diy-efi.org>
> >Sent: Friday, January 31, 2003 1:26 PM
> >Subject: [Diy_efi] Welding on cars w/ ECU's??
> >
> >
> >Can anybody explain to me why it is you can not (at least the aftermarket
> >manufacturers prefer that you not) weld on a vehicle while the ECU is
> >connected (electrically) to the vehicle?  It seems that muffler shops
weld
> >on vehicles with factory ecu's all day long without trouble, however I
have
> >heard many horror stories of damaged aftermarket ECU's and ignition boxes
> >when somebody neglected to disconnect the harnesses?  I have never really
> >been given a good answer, I just follow the rules and hope to avoid
> >disaster...
> >
> >-thanks
> >-Chris
> >
> >
> >
>
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