See the article on how the O2 sensor is used
by the engine computer.
________________
Date: Tue, 11 Apr 2000 21:07:17 -0400 Closed loop is only intended for light load cruising. you go out of closed
loop the moment you start loading the engine.
Latency of the o2 sensor is about 1/2 second (ie. readings are 1/2 second
old when read). No prob for cruising but instant death at full power WOT.
________________
Date: Wed, 14 Apr 1999 16:32:46 -0500 Here's the scoop as I understand it on this issue. First let me state that I have or
have had both on my car. Both being the PFS hooked into a standard O2 and heated O2
as well as the fancy $2000 wide range lambda which happens to be built into my Motec
currently on the car. The 4 wire wide range sensor can be had for a little less than
$400 but yes that's what's there.
I'm not up on my reading with respect to the function of the wide range, but have
done a reasonable amount on the normal and heated O2's in the past.
Accuracy
A normal O2 is actually very accurate, but only in a certain range which happens to
be close to stoich or 14.7 : 1 or .45 volts as an output from a normal sensor. What
happens is that the further from stoich you go with a normal O2 sensor the numbers
become more inaccurate with respect to an actual oxygen ratio present. A wide range
sensor is just like its name suggests, more accurate than a normal sensor at mixtures
further from stoich.
Relative Numbers
I'm currently using a wide range for the motec, because that's the only thing it
supports as well as my car being so far from any known 3rd gen configuration I can't
use relative numbers. In this case I'm not speaking of the PFS data logging of
numbers, only what is displayed on the older boxes with keypad. I would differ with
what others have stated in that you should ignore the numbers displayed from a normal
O2 sensor. While you can't extrapolate an actual AF ratio from the voltage on a
normal O2 sensor once it deviates any significant amount from stoich you can use the
voltage as a benchmark that others have used with success. If you recieve the same
voltage as another person has on a normal O2 sensor you can assume that your AF is
similar to theirs at that given time.You may not know exactly what AF that happens to
be but you really don't need to know. Since we do have relative numbers that have
worked for others in the past I would suggest that you can safely tune your car
within reason using numbers from a standard O2 sensor up to the point of about
450+HP. So what voltage numbers are reasonable? From my experience of a few years
doing it that way I found a good benchmark of .82 volts to be the leanest you want to
allow during WOT and higher boost, above 10-12psi. Voltage higher than that will be
richer and a bit safer until you reach a point of being excessively rich, which can
actually cause damage of its own, such as clogging cats, diluting lubrication in the
housings etc. So .82 -.86 is a good balanced range to be in. Just watch the keypad
numbers at wide open throttle in 3rd and 4th gear at 5000-8000 RPM. The number should
remain fairly constant. If the numbers drop below .82 let off the throttle and
increase the fuel in that range and test again. If higher than .86 remove fuel from
that range and test again. A little side observational info. When running leaded race
gas the heated O2 does read a slight bit differently given all other conditions being
the same. Off the top of my head it was about .76 = .82 or something like that. If
someones using C16 or something ask me directly about numbers to be used.
________________
From: Rob Robinette
How the O2 Sensor Works
The oxygen sensor detects oxygen in the exhaust in a way similar to a
battery cell. Platinum layers on the inside and outside of the probe act as
electrodes. Zirconium dioxide between the layers of platinum acts as an
electrolyte. The inside layer of platinum is exposed to the air in the
engine bay, the outer layer is exposed to the exhaust. When the O2 sensor
is hot it generates positive voltage between the two layers of platinum.
Negatively charged oxygen ions in the exhaust are attracted to the platinum
and reduce the voltage that the Engine Control Unit and air/fuel gauge
reads.
That's why a rich mixture = higher voltage from the sensor (more gas
= fewer negative O2 ions to drop the voltage) . Just remember "L=L", Lean =
Low voltage. You can attach a Volt Ohm meter (black to ground, red to the
O2 sensor) to monitor your engine's air/fuel ratio. Full throttle with 0.82
volts is best performance but slightly higher voltage (richer) is safe. At
part throttle the ECU will bounce the ratio from rich to lean. You only
have to worry about full throttle. I suggest you have a copilot read the
voltage while you accelerate at full throttle.
The 3 wire sensors are used to give power and ground to pre-heat the sensor
so it starts working quicker, it has no effect after the sensor gets warmed
up.
Date: Thu, 12 Jun 97 12:49:55 -0500 I bought the NAPA part below and have it installed on my 93-R1. If I
remember it was less than $60. It works fine and lets me mix in leaded
race gas (100-115 octane) at the track for the same price per gallon as the
no lead 100 octane race gas. Means I have to buy a lot less race gas to
raise the overall octane to a meanful level. Leaded gas will eventually
kill the heated O2 sensor but it takes a while (probably several seasons).
It will probably kill an unheated O2 sensor on the first tank. By the way,
one of my concerns was if I was going to have to use a funnel or get a gas
can to use leaded fuel since the filler on cars is designed to not allow
leaded gas in unleaded cars. At Road Atlanta at least, all the race gas is
pumped from the same nossels (leaded & unleaded) so it is not problems
(except for the Porsche PCA members who had been filling up with leaded Race
Gas for 2 days in their new 911's with full emmissions intact - leaded gas
also kills the CATs).
You will also probably want to get the 3 wire connector harness to
permanately replace the wiring harness side connector for the O2 sensor. I
got this at the Ford parts counter. It is a generic aftermarket item and
cost me $10. Have the O2 sensor with you because there are two plug types
and if you have my luck the first one you get will not fit.
Netblazer post:
You want one off a Ford Escort of all things. I grabbed the wiring
harness connector off one at a wrecking yard (make sure you don't tell
them what you are taking or they will FLIP since its part of the engine
harness :)
NAPA part No. OS204
Should have 3 wires (2 white, and 1 black) hook the white wires to pos,
12, and gnd, and hook the black wire to the wire where the old one hooked up.
___________________
Date: Thu, 8 Jan 1998 10:32:38 -0500 Napa part # OS204 for 86 Ford Escort, $39, 3 wires, black to O2 sensor, two
white to power and ground (optional).
The oxygen sensor is located on the exhaust pipe (pre-cat) between the
right front fender and the fire wall in the engine compartment. It is
sticking out from the exhaust pipe and has one wire attached to it. There
is a plastic connector on this wire above the sensor so you can disconnect
it.
You will have to solder the new O2 sensor's black wire to this
connector for reinstallation. The two white wires on the Napa sensor are
for 12 volt power and ground and heats the sensor. A heated sensor
supposedly works better with high octane racing fuel. You can leave these
white wires disconnected.
It's a good idea to spray the sensor with a
penetrating lubricant the night before you do the change to make the
removal a little easier. I would also recommend putting some anti-sieze
paste (available at Napa) on the threads of the new sensor before you
install it.
Overall the O2 sensor replacement is a straightforward job.
Good luck.
_________________
Date: Thu, 05 Mar 98 13:15:38 -0500 For immediate replacement, you do NOT need to connect ground and 12V for the
heating element. It works OK without heating it, just takes a few minutes
to warm up.
Buy it and buy the mating connector to put in your wiring harness at the
same time (i.e.- test it). About $10. If NAPA doesn't have it try a Ford
dealer.
_________________
Date: Tue, 03 Mar 1998 08:53:56 -0800 About a year ago I "retired" my stock O2 sensor.
I tried a plain $25 Bosch sensor, reacted very slow. Junk, trashed it.
Then I heard about this great Escort O2 sensor everybody was using on
this list. I got the part number from Sandy Lithium and bought one. It
was reading a little leaner that my stock 65k sensor was reading. But it
was doing so very consistently and quickly. I trashed it and got another
one just like it thinking that I either got a bad one or that I somehow
screwed it up by getting anti-sieze on the sensor or something.
Guess what? The second one acted the exact same way. Now I'm thinking my
car is running lean. I send my ECU to XS Engineering to get reprogramed.
Same readings, little richer, not much. I call XS and b%tch. They tell
me it's got to be my O2 sensor or my stock FPR. They run the fuel maps
at like 11.5:1 or 12:1. I replace my stock FPR with an adjustable one
they sell made by SX. O2 readings don't change. I don't want to jump to
any harsh conclusions, but I think the Escort O2 sensor is junk. I think
the O2 sensors on our cars actually cost around $200 bucks because they
are, sort of, high quality sensors. I had a long talk with Eric at XS
about O2 sensors. The only one he really trusts is his Motec (whatever
that is) He uses the sensors out of the new 96-98 Porsche Twin Turbos
when he can get somebody to spend the $1000 bucks for one.
New connector for the 3-wire sensor:
_________________
Date: Wed, 4 Mar 1998 09:33:26 +0000 Spencer Hutchings is upset because his Escort 02 sensor gives leaner
readings on his A/F meter than he was used to seeing from the stock
sensor.
When I was talking with the guys at Tri-Point, they said that they
liked to use Mazda O2 sensors with aftermarket engine management
systems because these systems were in closed loop mode (using
readings from the sensor) much more of the time. Tri-Point's
experience was that the original equipment sensor was more stable
over time than less costly alternatives, and more accurate.
Earlier Net discussion on the subject highlighted the fact that O2
sensors of all kinds are not very accurate (in an absolute sense)
when they are reading mixtures that extend near either end of their
ranges. Most of us with A/F meters figure where the car runs
best--usually near the rich end of the A/F meter display--and just
look for repeated readings. Many of the meters themselves are
purposefully vague about the readings--with actual values only being
stated for the ends of the range, and for the 14.7 to 1 reading.
That having been said, with the stock engine management system NOT
depending on the O2 sensor in full throttle situations, it comes
down to the same air/fuel mix being interpreted as a different voltage by
various O2 sensors. I can understand Spencer's frustration that his
ECU is seeing leaner readings from the Escort O2 sensor than from
the original. It just isn't "right." On the other hand, getting
used to a slightly different light pattern on his A/F meter should
not be a major hassle, and the worse that would happen from a
driving standpoint is that the ECU would make the mix a little
richer during closed loop operation--namely at relatively steady
state cruising.
There is a significant difference in cost between the O2 sensors in
question, so I guess each of us has to decide what the best value
is, what we can live with, and what will drive us crazy.
As for Spencer, he needs to go back to the stock unit. I thank him
for bringing up the differences to the list. It is valuable
information. Maybe someone wants to buy his Escort O2 sensor.
_________________
And one more response to Spencer's issues above. --Steve
Date: Tue, 03 Mar 98 12:36:14 -0500 If I had changed
nothing but the sensor, then I would simply ajust my interpertation of my
monitor's information accordingly, not go crazy swaping components trying
to get exactly the same readings.
I cannot compare the Escort sensor to the stock sensor technically, anymore
than you did, but no one I am aware of has had anymore trouble using it
than they did the stock sensor.
If values are different on your Cyberdyne, then either its impedence is too
low and it is dropping the voltage level of the sensor more than it did with
the stock sensor or maybe there is simply a small variance in the designs.
None of the stock sensors are suitable for precision measurement, which is
why closed loop operation is only used for idle and light to moderate
throttle. The O2 data is not used to meter fuel at all when you have to
worry about running lean (WOT or on boost), it uses its preset air/fuel maps.
________________
Date: Wed, 24 Feb 1999 09:08:45 -0600 I got a 4 wire sensor from pep boys for $36.99. 2 white wires (positive
and ground for the heating element) black (signal) and grey (sensor ground).
Works REALLY well. Just thought you all might want to know
OOPS.... fergot to say that it is off of a '98 camaro. pep boys, and it is
a Borg Warner part.
________________
From: Bob TMS Murray My next O2 sensor will be from Motec. Theirs is actually quite
reasonably priced at ~$95 - higher than a Ford or OEM, but we're not
talking about a lot of $ in the first place. I would investigate this -
as if it's good enough for WSC, it's probably sufficient for anything I'll
ever build.
_______________
Date: Wed, 24 Mar 1999 20:46:36 -0500 As another note, Motec's sensor and injector components are
simply off the shelf standard GM, Ford, Bosch components -
significantly marked up.
Nothing wrong with that, and they say they QC all the parts for
function and accuracy.
Date: Fri, 09 Jan 1998 18:15:15 -0500 Originally From: peter paul fenske (pfenske@direct.ca) For those interested in the Bosch lead tolerant O2 sensor, the part number
you want is: 0 258 104 002 also known as LSM11.
The correct "Quoted Life" in a leaded environment is: 100LL AVGAS contains .56 g/liter Pb.
I've been running mine since Oct 20th or so, without any problems yet on
nothing but AVGAS. Cost is roughly $270.
Date: Mon, 10 Apr 2000 23:01:26 +0000 Just some info on wide band O2 sensors... Feedback is
appreciated.
Demetrios and I have been swapping emails regarding O2
sensors for tuning the Haltech (and any other computer
that has adjustable fuel maps). We decided to take this
public in an effort to get a relevant thread going.
My orignal intention was to buy a wide-band O2 sensor
(Bosch Motorsports, approx. $) and datalog to the
Haltech. But hold everything...you can't do that. Wide
band O2's use a different type of input that cannot be
resolved as simply as the narrow band (the one-wire and
three wire O2's in most modern vehicles). Most wide-
band sensors, if not all, are a part of a "system",
wherein they are attached to a standalone computer to
sample (~25-30 samples per second), convert, dampen (to
~5 readings per second), and display the A/F ratio.
The net result of this is that discrete tuning of
adjustable ECU's will likely require at least one trip
to the dyno (or hook up w/ a buddy who has a wide-band
O2). Once that's done, ou can feel free to hook up a 3-
wire O2 to datalog for "skips" and giggles.
So, has anyone ever run a wide-band O2 to datalog w/o
using a computer to convert the O2 voltage?
_____________
Date: Tue, 11 Apr 2000 00:22:11 GMT Haltech can be configured for choosing what O2 sensor you
want to use for your car. My lambda unit has an output
port where I can tied to the haltech and configured the
haltech to read 0-5V range from the unit and still be
accurate. You can simply choose Bosch 0-5V O2 sensor and
tied that to your car without the lambda meter. The only
problem is that you'll have to convert a/f ratio into
voltage. I believed at 12:1 ratio, the voltage is around
78V for 0-1V range so basically you multiply that number
by 5 for 0-5volt range and it should be the same.
_____________
Date: Tue, 11 Apr 2000 12:41:06 +0000 As I understand it, after being schooled by Demetrios,
the benefits of running the Bosch Motorsports or NGK
wide band O2 sensor connected to the Haltech is that you
can datalog the results to disk during a run, and make
changes afterwards to all the applicable fuel maps.
Running in closed loop mode means that you intend to use
the O2 sensor as an input to the fuel map adjustments.
This effectively uses your base maps but makes +/- fuel
adjustments based on the O2 readings.
We talked about splitting the costs of the wide lambda
O2 + standalone computer but before I do that, I've
decided to buy just the Bosch Motorsports four-wire O2
sensor (this is important that you get a 4-wire for
tuning) and datalog/tune with it. If I need more
resolution, the box we talked about uses the Bosch
sensor, so I/we would only have to buy the box at that
point. Also, the sensor lasts about 500+ hours on pump
gas and about 50 for straight leaded/C16. The plan
would simply be to run the O2 for tuning and datalogging
and then hang it up. Fact of the matter is you could
run the O2 for MADS the whole weekend through and still
have plenty of life left in it. I plan to datalog my
MADS sessions and by that time, have an excel
spreadsheet with functions to graph 2-way and 3-way
plots (yeah, yeah, stay tuned). :-)
Date: Thu, 13 Apr 2000 17:50:58 -0700 I hooked up a high quality (Tektronix TX3) voltmeter
to my O2 sensor wire and did some voltage measurements
while driving around last weekend. I thought I
would share the results for those of you are interested.
My car is a completely stock 95 with 42K miles. Strong
runner with normal 11-9-11 boost pattern (4.6 second
40 to 70 MPH, 3rd gear WOT test).
Here are the results:
O2 Sensor Voltage Measurements
-----------------------------------
Engine coolant at full operating temperature.
At idle: At hiway cruise, 5th gear, 65 MPH, 2400 RPMs: V = 0.0 when cruising, and throttle is closed
(injectors are off). If you had leaky injectors
you may see something above 0 volts.
WOT after idling a long time (exh gas temp lowest,
and O2 sensor temp lowest) WOT after cruising moderate speed on highway (exh
gas temp higher than at idle) WOT after extended high loads (higher exh temps,
probably around 750 C = 1400 F) RPMs at 3500 in neutral System goes open-loop at approx. 3400 RPM, with or without a
load, even parked in neutral.
V = 0.90 to 0.91 even with very slight throttle
loads in open-loop mode (above 3400 RPMs or larger
throttle openings at < 3400 RPMs the system will
go from closed-loop to open-loop control. This is
why you never want to cruise on the hiway in 4th
gear and expect good gas mileage).
-----------------------------------
Note that the O2 sensor's output decreases slightly
when it gets hotter, even though the A/F mixture is
probably still at approx. 12:1. This is normal
according to reference info at:
http://robrobinette.com/autometer_af.htm
If you are interested on where that strange backwards
"S" shaped curve comes from and don't mind some nitty
gritty math, down-load my Excel file at the bottom
of Rob's referenced page. This derived information
confirms the basic curves provided by Autometer.
I know that using the stock O2 sensor is not the
most accurate thing to use, but its better than
nothing if you can't afford a $2500 wide-band
Lambda sensor kit. If the car was ultra lean you
should still be able to see it with the stock
O2 sensor (less than 0.87 volts at WOT with normal
exhaust temps of approx. 750 C (1400 F) which is
around 13:1 A/F ratio).
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[Copyright Notice]
Intro to O2 Sensors
From: "\(Mr\) Sandy Linthicum" (sandy-linthicum@nc.rr.com)
From: "Kevin T. Wyum" (aspi@winternet.com)
Replacement O2 Sensors
From: "Linthicum, Sandy"
From: Rob Robinette (robinett@postoffice.dca.net)
From: "Linthicum, Sandy" (linthias@sandy-ntws.usps.gov)
From: Spencer Hutchings (hutch@qnis.net)
From: "David Lane" (dlane@peabody.jhu.edu)
From: "Linthicum, Sandy" (linthias@sandy-ntws.usps.gov)
From: "Justin Arnold" (aarnold@pdq.net)
RPMEngineering
Date: March 24, 1999
From: Sandy Linthicum (sandy_linthicum@mindspring.com)
O2 Sensors for Leaded Gas
From: Jay Wallace (jwallace@nist.gov)
Sender: owner-diy_efi@efi332.eng.ohio-state.edu
at max .6 g/liter Pb, 20-30,000 km
at max .4 g/liter Pb, 30-50,000 km
at max .15 g/liter Pb, 80,000 km
Wide Band O2 Sensors
From: ryan.schlagheck@att.net
Subject: (rx7) [3] Wide Band Lambda O2 Sensor discussion?
From: skan@ticnet.com
From: ryan.schlagheck@att.net
O2 Sensor Readings
From: "Ulen, Robert S" (Robert.Ulen@PSS.Boeing.com)
Subject: (rx7) [3] O2 Sensor - Voltage Measurement Test
V = 45 to 50 mV.
V oscillates between 0.10 and 0.80 volts.
V = 0.94 to 0.95.
V = 0.91 to 0.92.
V = 0.90.