Homemade O2 Sensors

[jdanda at sunflower.com (James S. Danda)]

Thanks, I took off the sensor and re-built the connection using the straight
tube splice crimp connectors. I removed the platic insulation from the
connector before crimping the wires. I then re-insulated with heat shrink.
At this point I can't imagine that connectivty is a problem. Unforn, this
did not fix my problem.

Now I guess I'm going to run through the electrical tests outlined in
bentleys. I've done everything I can think of that is less than $100/part. I
don't want to chance spending money on a new coil or distributor if I'm not
98% convinced it needs replacing.

My next questions: Where can I buy some 'generic  vw/german' connectors to
build up the test harnesses required to perform the tests?

I'm getting real depressed with CIS-E. I have made the decision never to own
a car again with a hybrid mechanical/vacuum/electric fuel injection built in
the 80's. Its 70's carbs, or 90's computers for me from
now onward.

Jim
Go Navy!

----- Original Message ----- 
From: "Allyn" <amalventano@sc.rr.com>
To: "Ron Pieper" <rapieper@yahoo.com>; "James S. Danda"
<jdanda@sunflower.com>; <scirocco-l@scirocco.org>
Sent: Tuesday, February 10, 2004 10:54 AM
Subject: Re: Homemade O2 Sensors


> > (this opens the solder vs. crimp debate).
>
> here, i'll attempt a quick end to the crimp vs. solder debate.
>
> crimping or soldering work ALMOST equally well. to understand why you must
> see how the o2 sensor interface works. the o2 sensor outputs a small
voltage
> (~0.5v), and due to the method by which that voltage is made, it is very
> sensitive to loading. the slightest load will cause the voltage to drop
> below what it is supposed to be. for this reason, the thing that reads
this
> sensor (ecu) uses a circuit with a very high impedance input (similar to a
> digital voltmeter - which is also the reason that analog meters don't work
> well reading o2 sensors - as they load the output down too much).
>
> ok, so we basically have something making voltage that is very sensitive
to
> loading, and its measured with a circuit designed to put near-0 load on
the
> device being read.
>
> ok, now what all of this tech stuff does for us is show that electrically,
> it just doesnt matter if you solder or crimp this connection. reason being
> that since the sensor is read using very high impedance, small differences
> in resistance of the wiring will have no impact on the voltage reaching
the
> ecu. this is because there is ~0 current running through the o2 sensor
> wires, so changes in resistance of those wires have no impact on the
voltage
> reaching the other end (cant have voltage drop across the line when there
is
> no current running through it).
>
> ok, so we (thoroughly) covered the electrical. what remains is the
> mechanical. the reason some prefer crimping over solder is because solder
> joints usually fail. now dont get me wrong, solder IS the superior
> connection method, but not when it is done improperly. lets face it, your
> average joe cant pull off nuclear grade solder joints. if you dont
properly
> solder this connection, the solder wicks up the wire as its being
soldered,
> causing it to be rigid up to the point where the wicking ended. not
knowing
> this, the wire is not properly reinforced at the end of the wick, and this
> junction is allowed to take the bending force of the wire. keep this up a
> few times and the wire breaks at that junction.
>
> ...so its not that solder is bad, its that people shouldnt do it unless
they
> are competent enough to do it correctly.
>
> Al
>
> Allyn Malventano, ETC(SS), USN
> 87 Rieger Scirocco GTO 2.0 16v (daily driver, 190k, rocco #6)
> 86 Kamei Twin 16V Turbo Scirocco GTX (30% complete, rocco #7)
> 86.5 Occo 16v Trailer (rocco #8)
> 90 Passat GL 16V (the wifes new daily, 200k)
>
> ----- Original Message ----- 
> From: "Ron Pieper" <rapieper@yahoo.com>
> To: "James S. Danda" <jdanda@sunflower.com>; <scirocco-l@scirocco.org>
> Sent: Tuesday, February 10, 2004 10:37 AM
> Subject: Re: Homemade O2 Sensors
>
>
> > Yes, I installed the same Bosch sender in a Cabby some time ago...worked
> wonderfully.  Did you
> >
> > Should be OK...
> >
> > Ron
> >
> > --- "James S. Danda" <jdanda@sunflower.com> wrote:
> > > Has anyone had luck wiring up a Universal O2 sensor (ie Bosch 13913)
to
> a 16v CIS-E car?
> > >
> > > I have one wired and installed, but I'm having problems getting my car
> to run right. It misses
> > > under load. In other words when accelerating it accelerates
erratically.
> Eventually I reach
> > > steady speed and it runs great, but while accelerating it has power in
> bursts. Its like a switch
> > > is randomly thrown which gives small burst of full power. Otherwise
> power is at 75%(guess). Oh,
> > > and it only acts like this AFTER the engine has completely warmed up.
> > >
> > > I've done the following in trouble shooting: new filters(air, fuel),
new
> injector seals, new
> > > plugs and wires, checked for vacuum leaks, and built a new o2 sensor.
> > >
> > > I'm beginning to think its the o2 sensor, but like an idiot I threw
the
> old one away so I can't
> > > test it. It ran ok before changing my downpipe. While installing the
> downpipe I figured I'd
> > > replace the o2 sensor. I really don't want to spend $125 on an OEM
> sensor, but if that gets the
> > > car running right I'll start saving.
> > >
> > > Thanks,
> > > jim
> > > _______________________________________________
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> >
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