A hollowed cat reduces backpressure, but your FI system should
compensate.  I drove my '85 for 4 years with an empty cat with no
problems.

On 10/14/08, Dave Arthur <dave.arthur@nscc.ca> wrote:
> Hi Jim
>
> I have a 2.1 and have installed a S&S muffler on it. My cat has been
> emptied, it's just a place for the o2 sensor now. The rest of the exhaust is
> the stock pipes.
>
> I have a perfectly running 2.1, using Digifant. The cat *should* not make
> any difference to the running of the FI. It will of course make a difference
> to emissions.
>
> My FI troubleshooting started from a similar place to you. I installed a new
> o2 sensor, checked my blue temp sensor and made sure my throttle position
> sensor was working properly. In my opinion, the most likely culprit will be
> the throttle position sensor switch, it's a rather crude affair and any wear
> on the throttle body or the throttle stop will cause a maladjustment of the
> switch.
>
> Best Regards
>
> Dave
>
>
> On 14/10/08 10:06 AM, "Jim Johnston" <inmytree1@GMAIL.COM> wrote:
>
>> Hello all,
>>
>> Vehicle:  91 GL with 163,000+, manual
>> Location: Wilmington, NC
>>
>> I'm trouble shooting a stumbling idle.  I think I've found my problem. I
>> noticed the exhaust puffing and the muffler had some odd sounds coming
>> from
>> the muffler itself.  So I pulled the cat and muffler.  I only snapped two
>> of
>> the three bolts.  It turns out, my catalytic converter has nothing  left.
>> It's completely empty.  The previous owner had a S & S Exhaust system put
>> on
>> a few months before my taking ownership 3+ years ago.  The cat has big
>> dents
>> in it.  My theory is this: when the shop put on the new Header and
>> Muffler,
>> they cleaned out the Catalytic Converter.  In NC, vehicles older than 1996
>> do not require emissions testing.
>>
>> I started her up, while a bit loud, no more puff puff puff....
>>
>> Would running with an hollowed out cat lead to the muffler breaking down?
>>
>> Now I have to figure out if I have to buy a muffler from S & S or does a
>> stock muffler bolt up to the system.
>>
>>
>> Jim
>> Wilmington, NC
>

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