Where to mount O2 sensor bolt

[jkarlsso@metabolex.com (Jonas K.)]

On 5/5/02 8:03 AM, "Scirocco-Al" <scirocco-Al@insight.rr.com> wrote:

> Mount it exactly where the old one went.  If it read all 4 mount it at th=
e
> collector.  If it read just one make it read off of one of the main tubes=
.

The O2 sensor on the 4-2 8v Exhaust manifolds read all 4 cylinders. The nex=
t
time you have an EM out look at the O2 port and you'll see it reads all 4.
The 4-1 is probably the same (didn=B9t keep it around long enough to make not=
e
of it)

> Also, if your car didn't come with a heated 02 sensor then don't put one =
on.
> They are more expensive an you will have to figure out how to wire it.  B=
eyond
> that your cars computer won't look for it anyway until the coolant temp s=
ensor
> tells the computer the motors warm enough to do so, which really defeats =
the
> whole purpose of having a heated sensor.

I disagree, the cost of a "universal" Bosch O2 sensor is only like $45 IIRC=
.
A universal single wire is $30. Chris D. just said how to wire it in. Havin=
g
a heated sensor when the location is far from the head will provide a much
more stable signal. I havn't done any testing on which reaches proper/activ=
e
temperature first (exhast @2ft from head, or CTS), but I'd want quite a bit
of margin. Especially if there's a cat in there to burn out with excess
fuel.=20
>=20
> I tried mounting a 4 into 1 on my 84 and had the sensor at the collector.=
  Ran
> like crap and I couldn't get it adjusted right.  Switched to a tri-y with=
 the
> sensor in the original location, easily adjusted the mixture and it runs =
fine.

Sounds like you should have used a heated sensor. :-) It would have been
cheaper to go with the heated sensor, plus the 4-1 header makes more power.
 =20
> Think of it this way.  Your sensor reads the amount of oxygen in the exha=
ust
> stream.  If you mount it where you have 4 times the exhaust then it will =
read
> 4 times the oxygen and think the car is running lean.

The sensor compares oxygen content in the exhaust to oxygen content in
ambient air. It only measures a tiny bit of gas from each.

Every one agrees, if the sensor is far from the head, it needs to be heated=
.
There will not be a problem with putting the sensor on only one pipe, but i=
f
something goes wrong on that pipe, then the others will be compensated for
inappropriately. Not the best scenario.

Go with Chris D's suggestion, a heated O2 sensor at the collector.
=20
Jonas