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Re: [Tech]: O2 sensors



Well now, that is actually a very good question since the O2 sensor is
suppose to save the Cat from premature failure and aid in economy, why not
disconnect it as long as your cat is gone?  The answer to this actually
depends on your knowledge of your fuel system.  I would suspect if you know
enough about your fuel system to be able to keep it from either fouling your
plugs by drowning them in fuel or burning a valve by creating a "too lean"
situation, and you are willing to take the risk, experiment with it.
There's probably someone who has actually done this successfully and could
explain the system to you.  I suspect that in the CIS system you are dealing
with (since it is as early as it is), the only reason for the O2 sensor is
to keep the cat from burning up.  Since the early CIS systems are not
electronic at all (atleast nothing like CIS-E systems), I wouldn't see any
problems with atleast experimenting but keeping an eye on the air/fuel
mixture of course!!  HTH!!

Davee

> Ok, now you've peaked my interest.
> What if you are running the early (1981-US/CA) CIS system and you have the
> Oxygen sensor but removed the Cat.
>
> Question is:
> Can/Should I disconnect the O2 sensor from the system and just run the
> signal wire to my air/fuel mixture gauge?
> I would obviously have to reconnect it when I put the Cat back in and have
> it smog'd every 2 years.
> Will I notice any gains or will this be a detriment to the CIS system?
> Thanks,
>
> Randy B  "I hugged a tree last week for pennance"
> Mars 81S - techtonics tuning 1847cc 8V
> Cosmos 81S - future project - dreaming of 200-220hp.
> 87 Jetta GLI 16V - daily driver
>
> -----Original Message-----
> From: Jonas Karlsson [SMTP:jonas85k@hotmail.com]
> Sent: Monday, December 04, 2000 9:13 AM
> To: Captnbr@aol.com; roccophil@mindspring.com;
> scirocco-l@scirocco.org
> Subject: Re: Tech (RANT) : O2 sensors
>
> >From: Captnbr@aol.com <mailto:Captnbr@aol.com>
>
> >roccophil@mindspring.com writes:
> >
> ><< O2 sensors - for those of you who disconnect them -
> DON'T!
> >
> >Yeah, ok I know I'm a dumbass.  But , is it true that the
> euro 16v's do not
> >have O2 sensors?  I thought I heard that once before. And
> don't they put
> >out a little more HP.  So are they just missing the o2
> sensor >or do they
> >have a completely different engine management system. later
>
> Not that I'm an expert on the euro 16v fuel systems or anything, but
> here's a lowdown on some FI basics.
> First, exessive unburnt fuel will kill a catalytic converter in
> no-time.
> That should scare you 16V guys a bit (with the integral downpipe/cat
> unit.
> $$$)
>
> The famed euro 16v injection systems were straight CIS. If there was
> no cat used, as Euro listers indicate, then there was little need for an
O2
> sensor.  The system as a whole was designed for this however. Most of the
> power increase seems to be due to lack of cat and 50mm intake/euro cam.
> KE-jetronic (AKA CIS-E) that is used on US cars was designed to very
> precisely control the air-fuel mixture (to reduce emissions and prevent
cat
> death). To do this there needs to be a O2 sensor (connected). Merely
> disconnecting the O2 sensor will not yield a euro system but will cause
your
> car to run like crap. The system will not be able to contol A/F mixture,
and
> performance will suffer.
> Basically maximum performance comes at a slightly rich mixture.
> Bosch knows this (that's what we pay them for) and they design FI systems
> that work very well to maintain a mixture that is on the money. Modifying
> the stock system (even if you know what you are doing) usually is not very
> successful and requires many hours of testing to make sure that everything
> works right.
> Until you're pushing 180 HP the stock system will work very well to
> deliver fuel at the proper amount.
> HTH
> Jonas
> 85 Scirocco 2.0
> 78 Scirocco 1.8
> For direct reply: jonas@metabolex.com <mailto:jonas@metabolex.com>
> http://www.geocities.com/scirocco2l8v
> <http://www.geocities.com/scirocco2l8v>
>
>
>
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