Re: Two little holes in Catalytic converter

[Mark Denovich <mark@domain.elided>]

> From: Joe Elliott <jee@domain.elided>
> I'm guessing that your welding may have fried something.  The oxygen 
> sensor would seem to be a likely victim, but since it doesn't come 
> into play in a cold start, I fear for your ECU.

Well there doesn't seem to be any problem at all.   It fired up in less 
than a half second this morning.   My guess is that the engine got just 
warm enough to prevent the cold start injector from firing, but was 
still cold enough that it could use it.

As for MIG welding frying my ECU...  Odds are if I were going to fry it 
I'd have done it a long long time ago.   I've laid about 12lbs of MIG 
wire on this car in the last few months, with no ill effect.   The 
concensus on sci.engr.joining.welding seems to be to disconnect the 
negative terminal of the battery to break any induction loop.   However, 
it should be noted that most of the muffler shops (MIDAS, etc.) don't 
bother (otherwise they'd be having to deal with radio's requesting 
codes, and customers PO'd about losing their presets.)  The incidence of 
problems must be pretty low.

I always make sure to have a good ground, and the clamp as close as 
possible to the piece I'm welding.

	--Mark

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