Adding an O2 sensor?

really? can you post a pic? it's hard to imagine the point of running
fuel injection absent the sensor because without it, the ecu doesn't
know for sure how much gas to inject.

Post by sharx333
My
question is, is this a great disadvantage in terms of mileage? Average
mileage for civics here is 18 to 24 MPG (~8-10km/liter).
Is the ECU always running in open loop mode?

presumably.

Post by sharx333
Can we somehow buy an O2
sensor and put it in, and if so, will this buy us much MPG-wise?

presumably, but you may need to do extensive wiring mods. it could save
you significantly in gas.

Post by sharx333
Thanks so much in advance.

double check on this "common knowledge" thing - i've never seen any
electronic fuel injection system that doesn't have a sensor - without
it, the ecu is "blind". check both sides of the cat as well as in the
manifold. it would be amazing if one wasn't there somewhere.

John Horner

2006-09-10 04:04:16 UTC

Post by jim beam
double check on this "common knowledge" thing - i've never seen any
electronic fuel injection system that doesn't have a sensor - without
it, the ecu is "blind". check both sides of the cat as well as in the
manifold. it would be amazing if one wasn't there somewhere.

Interesting. Early fuel injection systems sold in the US were indeed
open loop designs, such as the Bosch D-Jetronic which was installed on
many late 1960s and early 1970s era Volkswagens and Volvos. Closed loop
came into general use about the same time as three way catalytic
converters did. Late 1970s and onward.

I suppose that it is possible that car makers built open loop versions
for countries without emissions regulations much later than the 1980s,
but I have no idea how it was done or if it is possible to easily
convert such systems to closed loop operations.

John

sharx333

2006-09-10 15:06:58 UTC

Hello again and thanks for the replies. I've posted photos at this
link, if you're interested:

http://hondaswap.com/ecus-electronics-tuning/car-has-no-o2-sensor-can-i-73624/#post698583

I think this version (ESi, Philippines) is a "stripped-down" version,
if you will, of the EG 4-door coupe (92-95) with a D16Z6 engine, minus
the VTEC. I've been using the service manual for some time now, and all
other parts match. The manual doesn't say anything about other O2
sensors though.

This may have been done to make it more affordable, even though at the
time this was the top-of-the-line model here. Also, the emission laws
here aren't as strict as in the U.S., and back in the early '90's they
were even less so.

Am I missing something here?? Are our civics "crippled"?

Interesting. Early fuel injection systems sold in the US were indeed
open loop designs, such as the Bosch D-Jetronic which was installed on
many late 1960s and early 1970s era Volkswagens and Volvos. Closed loop
came into general use about the same time as three way catalytic
converters did. Late 1970s and onward.
I suppose that it is possible that car makers built open loop versions
for countries without emissions regulations much later than the 1980s,
but I have no idea how it was done or if it is possible to easily
convert such systems to closed loop operations.
John

jim beam

2006-09-10 15:33:00 UTC

Post by sharx333
Hello again and thanks for the replies. I've posted photos at this
http://hondaswap.com/ecus-electronics-tuning/car-has-no-o2-sensor-can-i-73624/#post698583
I think this version (ESi, Philippines) is a "stripped-down" version,
if you will, of the EG 4-door coupe (92-95) with a D16Z6 engine, minus
the VTEC. I've been using the service manual for some time now, and all
other parts match. The manual doesn't say anything about other O2
sensors though.
This may have been done to make it more affordable, even though at the
time this was the top-of-the-line model here. Also, the emission laws
here aren't as strict as in the U.S., and back in the early '90's they
were even less so.
Am I missing something here?? Are our civics "crippled"?

it certainly looks that way! john raises the good point about
pre-catalyst injection systems not having sensors [i'd forgotten that -
it's /so/ long since i've seen one!] and you've posted the pics. but it
still amazes me. the cost of a sensor, in bulk, to a manufacturer has
got to be less than $50. it's astonishing that honda would elect not to
use one - maybe there was a legal reason.

getting back to your original question, you can almost certainly
retrofit, but there will obviously be wiring involved and it would
probably require acquisition of a new ecu. interesting project though!
and you may as well go for the vtec while you're at it!

Interesting. Early fuel injection systems sold in the US were indeed
open loop designs, such as the Bosch D-Jetronic which was installed on
many late 1960s and early 1970s era Volkswagens and Volvos. Closed loop
came into general use about the same time as three way catalytic
converters did. Late 1970s and onward.
I suppose that it is possible that car makers built open loop versions
for countries without emissions regulations much later than the 1980s,
but I have no idea how it was done or if it is possible to easily
convert such systems to closed loop operations.
John

sharx333

2006-09-11 10:27:11 UTC

Post by sharx333
Am I missing something here?? Are our civics "crippled"?

it certainly looks that way! john raises the good point about
pre-catalyst injection systems not having sensors [i'd forgotten that -
it's /so/ long since i've seen one!] and you've posted the pics. but it
still amazes me. the cost of a sensor, in bulk, to a manufacturer has
got to be less than $50. it's astonishing that honda would elect not to
use one - maybe there was a legal reason.
getting back to your original question, you can almost certainly
retrofit, but there will obviously be wiring involved and it would
probably require acquisition of a new ecu. interesting project though!
and you may as well go for the vtec while you're at it!

Now that you mentioned it, it's also "common knowledge" here that this
ESi doesn't have a catalytic converter! I'll have to go check.. where
might it be located?

jim beam

2006-09-11 12:49:55 UTC

Post by sharx333
Am I missing something here?? Are our civics "crippled"?

it certainly looks that way! john raises the good point about
pre-catalyst injection systems not having sensors [i'd forgotten that -
it's /so/ long since i've seen one!] and you've posted the pics. but it
still amazes me. the cost of a sensor, in bulk, to a manufacturer has
got to be less than $50. it's astonishing that honda would elect not to
use one - maybe there was a legal reason.
getting back to your original question, you can almost certainly
retrofit, but there will obviously be wiring involved and it would
probably require acquisition of a new ecu. interesting project though!
and you may as well go for the vtec while you're at it!

Now that you mentioned it, it's also "common knowledge" here that this
ESi doesn't have a catalytic converter! I'll have to go check.. where
might it be located?

it's a huge bump in the exhaust, round about where the passenger seat
is. but if you don't have an oxygen sensor, you won't have a cat.

regarding retrofit, it's not essential to have the cat. - the important
bit is the sensor.

Matt Ion

2006-09-12 05:35:06 UTC

Post by sharx333
Am I missing something here?? Are our civics "crippled"?

it certainly looks that way! john raises the good point about
pre-catalyst injection systems not having sensors [i'd forgotten that -
it's /so/ long since i've seen one!] and you've posted the pics. but it
still amazes me. the cost of a sensor, in bulk, to a manufacturer has
got to be less than $50. it's astonishing that honda would elect not to
use one - maybe there was a legal reason.
getting back to your original question, you can almost certainly
retrofit, but there will obviously be wiring involved and it would
probably require acquisition of a new ecu. interesting project though!
and you may as well go for the vtec while you're at it!

Now that you mentioned it, it's also "common knowledge" here that this
ESi doesn't have a catalytic converter! I'll have to go check.. where
might it be located?

it's a huge bump in the exhaust, round about where the passenger seat
is. but if you don't have an oxygen sensor, you won't have a cat.

Tell that to my '87 Accords, all of which have had cats and no O2 sensors.

Or my old '80 Mazda GLC, for that matter.

Post by jim beam
regarding retrofit, it's not essential to have the cat. - the important
bit is the sensor.

The cat IS essential if your local emissions laws require it!

jim beam

2006-09-12 05:50:57 UTC

Post by sharx333
Am I missing something here?? Are our civics "crippled"?

it certainly looks that way! john raises the good point about
pre-catalyst injection systems not having sensors [i'd forgotten that -
it's /so/ long since i've seen one!] and you've posted the pics.
but it
still amazes me. the cost of a sensor, in bulk, to a manufacturer has
got to be less than $50. it's astonishing that honda would elect not to
use one - maybe there was a legal reason.
getting back to your original question, you can almost certainly
retrofit, but there will obviously be wiring involved and it would
probably require acquisition of a new ecu. interesting project though!
and you may as well go for the vtec while you're at it!

Now that you mentioned it, it's also "common knowledge" here that this
ESi doesn't have a catalytic converter! I'll have to go check.. where
might it be located?

it's a huge bump in the exhaust, round about where the passenger seat
is. but if you don't have an oxygen sensor, you won't have a cat.

Tell that to my '87 Accords, all of which have had cats and no O2 sensors.
Or my old '80 Mazda GLC, for that matter.

ok.

Post by jim beam
regarding retrofit, it's not essential to have the cat. - the
important bit is the sensor.

The cat IS essential if your local emissions laws require it!

indeed, but this is apparently not the case for the o.p.

Grumpy AuContraire

2006-09-12 12:53:46 UTC

Post by sharx333
Am I missing something here?? Are our civics "crippled"?

it certainly looks that way! john raises the good point about
pre-catalyst injection systems not having sensors [i'd forgotten that -
it's /so/ long since i've seen one!] and you've posted the pics. but it
still amazes me. the cost of a sensor, in bulk, to a manufacturer has
got to be less than $50. it's astonishing that honda would elect not to
use one - maybe there was a legal reason.
getting back to your original question, you can almost certainly
retrofit, but there will obviously be wiring involved and it would
probably require acquisition of a new ecu. interesting project though!
and you may as well go for the vtec while you're at it!

Now that you mentioned it, it's also "common knowledge" here that this
ESi doesn't have a catalytic converter! I'll have to go check.. where
might it be located?

it's a huge bump in the exhaust, round about where the passenger seat
is. but if you don't have an oxygen sensor, you won't have a cat.

Tell that to my '87 Accords, all of which have had cats and no O2 sensors.
Or my old '80 Mazda GLC, for that matter.

...or my '82 & 83 Civics.

Post by jim beam
regarding retrofit, it's not essential to have the cat. - the important
bit is the sensor.

The cat IS essential if your local emissions laws require it!

'82 is exempt and '83 soon will be!

JT

Matt Ion

2006-09-12 14:52:21 UTC

Post by Grumpy AuContraire

Post by sharx333
Am I missing something here?? Are our civics "crippled"?

it certainly looks that way! john raises the good point about
pre-catalyst injection systems not having sensors [i'd forgotten that -
it's /so/ long since i've seen one!] and you've posted the pics. but it
still amazes me. the cost of a sensor, in bulk, to a manufacturer has
got to be less than $50. it's astonishing that honda would elect not to
use one - maybe there was a legal reason.
getting back to your original question, you can almost certainly
retrofit, but there will obviously be wiring involved and it would
probably require acquisition of a new ecu. interesting project though!
and you may as well go for the vtec while you're at it!

Now that you mentioned it, it's also "common knowledge" here that this
ESi doesn't have a catalytic converter! I'll have to go check.. where
might it be located?

it's a huge bump in the exhaust, round about where the passenger seat
is. but if you don't have an oxygen sensor, you won't have a cat.

Tell that to my '87 Accords, all of which have had cats and no O2 sensors.
Or my old '80 Mazda GLC, for that matter.

...or my '82 & 83 Civics.

Post by jim beam
regarding retrofit, it's not essential to have the cat. - the important
bit is the sensor.

The cat IS essential if your local emissions laws require it!

'82 is exempt and '83 soon will be!

Again, depends on your local laws. In BC, if the car came from the manufacturer
with a cat, then it must always have a cat. In most of the province, nobody
will usually notice or care, but legally it must still be there; in the
Vancouver area, where we also have emissions testing, the car won't pass if it
originally had a cat that's now missing, regardless of the year.

sharx333

2006-09-12 14:02:39 UTC

Post by Matt Ion
The cat IS essential if your local emissions laws require it!

Actually the emissions laws here *don't* require it. Even today I
haven't seen any cars that have Cats. But regarding retrofit, TeGGer
over at rec.autos.makers.honda says:

"On road-going cars, the primary purpose of O2 sensors and their
associated hardware/software is emissions, not mileage. Any mileage
increase you see (if any), would be a bonus, and would be a
side-effect.
Some race cars use oxygen sensors to improve mileage during a race, but

these are using ECUs programmed for mileage. Stock ECUs are programmed
for emissions.
. . .
You should count yourself lucky to live in a jurisdiction with more
reasonable emissions laws and thus a simpler vehicle. Honda OEM oxygen
sensors and cats are priced in the hundreds of dollars."

I respect TeGGer's responses, but do you guys think he's right on this
one? What if our cars here in the Philippines are programmed for
mileage, instead of emissions as TeGGer says?

Matt Ion

2006-09-12 14:57:22 UTC

Post by Matt Ion
The cat IS essential if your local emissions laws require it!

Actually the emissions laws here *don't* require it.

Fair'nuff... it was more of a generic response to Jim's comment that a cat is
"not essential".

Post by sharx333
I respect TeGGer's responses, but do you guys think he's right on this
one? What if our cars here in the Philippines are programmed for
mileage, instead of emissions as TeGGer says?

I'd suspect it's more likely the various parts were left out for cost savings,
with no regard for emissions OR mileage.

sharx333

2006-09-12 20:07:01 UTC

Post by sharx333
Actually the emissions laws here *don't* require it.

Fair'nuff... it was more of a generic response to Jim's comment that a cat is
"not essential".

Oh, no slight meant there, Matt. I was just making it clear that I'm
not contemplating anything illegal :)

Anyway, I'm somewhat confused by TeGGer's response over at
rec.autos.makers.honda, where he says that the O2 sensor is simply
there for emissions. He's a resident guru there and I'm inclined to
believe him, but OTOH when someone asks about poor mileage, group
posters usually point to the O2 sensor as the culprit. Also, most
references on the net say that the sensor is vital for normal running.

Anyone have any idea on how this ECU was tweaked to run without an
oxygen sensor? How does running in open loop affect things?

Jim Yanik

2006-09-12 20:47:01 UTC

Post by sharx333
Actually the emissions laws here *don't* require it.

Fair'nuff... it was more of a generic response to Jim's comment that
a cat is "not essential".

Oh, no slight meant there, Matt. I was just making it clear that I'm
not contemplating anything illegal :)
Anyway, I'm somewhat confused by TeGGer's response over at
rec.autos.makers.honda, where he says that the O2 sensor is simply
there for emissions. He's a resident guru there and I'm inclined to
believe him, but OTOH when someone asks about poor mileage, group
posters usually point to the O2 sensor as the culprit. Also, most
references on the net say that the sensor is vital for normal running.
Anyone have any idea on how this ECU was tweaked to run without an
oxygen sensor? How does running in open loop affect things?

Open loop makes the fuel-air mix richer than optimal(for emissions) ALL the
time,just as it does until the engine warms up to operating temperature.You
have to avoid a too-lean condition in -all- operating conditions,to avoid
damaging the engine.

Closed loop optimizes the fuel-air mix for the leanest possible mix -
without- risking a too-lean condition that could burn a piston or make the
motor run too hot.It minimizes the extra hydrocarbons (rich exhaust)that
the cat-converter has to burn up,for best emissions.

You have a open-loop at the start because the catalytic has not warmed up
yet,nor has the motor.(coolant,plugs)

--
Jim Yanik
jyanik
at
kua.net

sharx333

2006-09-12 21:56:00 UTC

Post by Jim Yanik
Open loop makes the fuel-air mix richer than optimal(for emissions) ALL the
time,just as it does until the engine warms up to operating temperature.You
have to avoid a too-lean condition in -all- operating conditions,to avoid
damaging the engine.
Closed loop optimizes the fuel-air mix for the leanest possible mix -
without- risking a too-lean condition that could burn a piston or make the
motor run too hot.It minimizes the extra hydrocarbons (rich exhaust)that
the cat-converter has to burn up,for best emissions.
You have a open-loop at the start because the catalytic has not warmed up
yet,nor has the motor.(coolant,plugs)

This makes a lot of sense.. So a sensor retrofit would be useful then?

Post by Jim Yanik
Some adventurous soul here could disconnect their O2 sensor and see if the
ECU then flashes the "check engine" light. A brief test.

If only some kind soul would try this... :) But I think the ECU would
just throw a CEL. I'll look at the ECU pinouts today, and post back.

Jim Yanik

2006-09-13 03:09:12 UTC

Post by Jim Yanik
Open loop makes the fuel-air mix richer than optimal(for emissions)
ALL the time,just as it does until the engine warms up to operating
temperature.You have to avoid a too-lean condition in -all- operating
conditions,to avoid damaging the engine.
Closed loop optimizes the fuel-air mix for the leanest possible mix -
without- risking a too-lean condition that could burn a piston or
make the motor run too hot.It minimizes the extra hydrocarbons (rich
exhaust)that the cat-converter has to burn up,for best emissions.
You have a open-loop at the start because the catalytic has not
warmed up yet,nor has the motor.(coolant,plugs)

This makes a lot of sense.. So a sensor retrofit would be useful then?

I doubt it would be worth the expense.
Considering you would have to change the ECU in addition. That's big bucks.
If you're looking for better gas mileage,changing your driving habits would
be far more productive,keeping your tires inflated properly.

Post by Jim Yanik
Some adventurous soul here could disconnect their O2 sensor and see
if the ECU then flashes the "check engine" light. A brief test.

If only some kind soul would try this... :) But I think the ECU would
just throw a CEL.

It's supposed to;it's a failure of the O2 sensor(missing = "open"
sensor),and the control loop is no longer closed,emissions not controlled.

Post by sharx333
I'll look at the ECU pinouts today, and post back.

Your car should have a *different ECU* if it does not have an O2 sensor.
Honda kept the same wiring harness for cost and simplicity,but the ECU
would have to have different programming to ignore the missing O2 sensor
and not flash the CEL.
Since Honda solders in their PROMs,ECUs are different.

--
Jim Yanik
jyanik
at
kua.net

sharx333

2006-09-13 11:59:14 UTC

Post by Jim Yanik
I doubt it would be worth the expense.
Considering you would have to change the ECU in addition. That's big bucks.
If you're looking for better gas mileage,changing your driving habits would
be far more productive,keeping your tires inflated properly.

Thanks, jim. You make a good point.

I'm really curious about this "open" vs "closed" loop mode. Are we
greatly disadvantaged by always running in open loop? Or are we "lucky"
as TeGGer says? Can't an ECU run in closed loop using just MAP, TPS,
TA, etc sensors?

jim beam

2006-09-13 13:19:29 UTC

Thanks, jim. You make a good point.
I'm really curious about this "open" vs "closed" loop mode. Are we
greatly disadvantaged by always running in open loop? Or are we "lucky"
as TeGGer says? Can't an ECU run in closed loop using just MAP, TPS,
TA, etc sensors?

no, it needs to know "lambda", the actual ratio of fuel to air the
engine is experiencing. the only way to do that is with a sensor.
older sensors only detected what's called "stoichiometry", i.e. when the
mix is perfect. newer sensors are "broad band" and detect the range
typically sought, i.e. lambda from 0.8 to 1.2. [the former is lean, the
latter rich - and peak torque.] either way, a sensor allows the ecu to
tune the engine perfectly for its running conditions. closed loop is
the way to go.

if you want to retrofit, you could look at this as a science experiment
and buy a used ecu online from the states. they're typically in the $30
to $100 range for the standard models.

Matt Ion

2006-09-13 15:09:23 UTC

Thanks, jim. You make a good point.
I'm really curious about this "open" vs "closed" loop mode. Are we
greatly disadvantaged by always running in open loop?

Well, it's worked for over 100 years... your average classic muscle car has
virtually nothing in the way of "engine management".

Jim Yanik

2006-09-13 15:42:25 UTC

Post by Jim Yanik
I doubt it would be worth the expense.
Considering you would have to change the ECU in addition. That's big
bucks. If you're looking for better gas mileage,changing your driving
habits would be far more productive,keeping your tires inflated
properly.

Thanks, jim. You make a good point.
I'm really curious about this "open" vs "closed" loop mode. Are we
greatly disadvantaged by always running in open loop?

Well, it's worked for over 100 years... your average classic muscle
car has virtually nothing in the way of "engine management".

Often,those "classic muscle cars" would not run well in other than optimal
weather or driving conditions.

--
Jim Yanik
jyanik
at
kua.net

Jim Yanik

2006-09-13 15:56:42 UTC

Post by Jim Yanik
I doubt it would be worth the expense.
Considering you would have to change the ECU in addition. That's big
bucks. If you're looking for better gas mileage,changing your driving
habits would be far more productive,keeping your tires inflated
properly.

Thanks, jim. You make a good point.
I'm really curious about this "open" vs "closed" loop mode. Are we
greatly disadvantaged by always running in open loop? Or are we
"lucky" as TeGGer says? Can't an ECU run in closed loop using just
MAP, TPS, TA, etc sensors?

"closed loop" is just using feedback from the O2 sensor to continually
adjust input fuel/air mix to optimum. Fine tuning on the run.

"open loop" is just "dump enough gas in to make it run" for a wide range of
conditions. There's no correctional feedback.

Without the sensor measuring at the END of the combustion process,it's not
"closed loop".

the "loop" is; input..combustion..output..*measure output*..make CORRECTION
to input;repeat.
Without the correction,there's no "loop",it's an "open-ended" process.
The closure is the feedback corrections.

Think of the AC and thermostat in your home; you set a temp,and the AC
runs,cools the room,and the TS measures what the room temp is,and when it
reaches your setpoint,it shuts off the AC,and cycles. That's "closed
loop".

"Open loop" would be you turning on the AC and running it for 10 minutes
every hour,say on a timer.
The room MAY be close to where you want it,perhaps not.That would depend on
how hot the room was to begin,and how how it is outside.
There's no measurement and feedback control.

--
Jim Yanik
jyanik
at
kua.net

sharx333

2006-09-13 20:23:55 UTC

Post by Jim Yanik
"closed loop" is just using feedback from the O2 sensor to continually
adjust input fuel/air mix to optimum. Fine tuning on the run.
"open loop" is just "dump enough gas in to make it run" for a wide range of
conditions. There's no correctional feedback.
Without the sensor measuring at the END of the combustion process,it's not
"closed loop".

Thanks. I think I see now. That since the main output of the ECU is the
injector duration, then the main input (to have a true feedback
"closed" loop) is a sensor that measures the effects of combustion (O2
sensor).

So I take it you mean that based on the other sensors (MAP, TA, TPS,
PA), the ECU does no fine tuning based on real-time combustion result,
but rather only bases the injector duration on predefined "maps" in its
ROM. So, the ECU does vary the injector duration and spark timing, but
only based on what it "thinks" is best for a given situation, but would
still not be "closed loop". You really need to somehow measure the
exhaust. Is my understanding correct?

This makes sense, but isn't the O2 sensor just another input for the
ECU? Is it any different from the other sensors, that the ECU uses to
vary timing and injection? What makes O2 so special, if the responses
to it are also based on a ROM "map"?

TIA

jim beam

2006-09-14 02:53:01 UTC

yes.

Post by sharx333
So I take it you mean that based on the other sensors (MAP, TA, TPS,
PA), the ECU does no fine tuning based on real-time combustion result,
but rather only bases the injector duration on predefined "maps" in its
ROM.

yes.

Post by sharx333
So, the ECU does vary the injector duration and spark timing, but
only based on what it "thinks" is best for a given situation, but would
still not be "closed loop".

yes.

Post by sharx333
You really need to somehow measure the
exhaust. Is my understanding correct?

absolutely.

Post by sharx333
This makes sense, but isn't the O2 sensor just another input for the
ECU?

yes.

Post by sharx333
Is it any different from the other sensors, that the ECU uses to
vary timing and injection? What makes O2 so special, if the responses
to it are also based on a ROM "map"?

based on the maps and readings of the sensors, including lambda, the ecu
can then compute in real time the precise amount of fuel to be injected.

if you're interested, there's an open source injector project out there
called [charmingly] "megasquirt". once googled, you can read the whole
nine yards about how injection works, even source code an ecu runs on.

Jim Yanik

2006-09-14 03:07:45 UTC

Post by Jim Yanik
"closed loop" is just using feedback from the O2 sensor to
continually adjust input fuel/air mix to optimum. Fine tuning on the
run.
"open loop" is just "dump enough gas in to make it run" for a wide
range of conditions. There's no correctional feedback.
Without the sensor measuring at the END of the combustion
process,it's not "closed loop".

Thanks. I think I see now. That since the main output of the ECU is
the injector duration, then the main input (to have a true feedback
"closed" loop) is a sensor that measures the effects of combustion (O2
sensor).
So I take it you mean that based on the other sensors (MAP, TA, TPS,
PA), the ECU does no fine tuning based on real-time combustion result,
but rather only bases the injector duration on predefined "maps" in
its ROM. So, the ECU does vary the injector duration and spark timing,
but only based on what it "thinks" is best for a given situation, but
would still not be "closed loop". You really need to somehow measure
the exhaust. Is my understanding correct?

Excellent!

Post by sharx333
This makes sense, but isn't the O2 sensor just another input for the
ECU? Is it any different from the other sensors, that the ECU uses to
vary timing and injection? What makes O2 so special, if the responses
to it are also based on a ROM "map"?

Well,the desired end result is complete combustion(a clean exhaust),and
exhaust O2 content is an indication of how well that's happening.
They are real-time corrections,and measure ACTUAL exhaust output.
(if a plug misfires,or a input-condition sensor is inaccurate,this feedback
corrects for it.it also allows for individual cylinders' injectors to be
corrected,compensating for differing air flow thru the cylinders.They are
not necessarily all equal!)

I believe there may be two 'maps".
One for open-loop,and one for when everything warms to operating temp.
The 2nd map would be much simpler,and smaller in data size,or just a
refinement on (or corrections for) the primary map.
It's like the ECU first sets injector duration for the TPS,IAT,MAP and RPM
via the map,and -then- looks at O2S data and fine-tunes if needed (at op
temp) for optimal exhaust O2 content. It also minimizes the work the
catalytic has to do,-and makes it last longer.

It does take some amount of time to balance the loop once a variable is
changed.(like throttle position or intake air temp)
Loop response cannot be instant,there's always some hysteresis,but it's
inconsequential,until the O2 sensor gets "slow" in it's response(degrades).

OBD-II systems supposedly measure this O2S response time and set a trouble
code (and CEL)if it gets too long(or fails),and also uses a 2nd O2 sensor
to back up the first sensor and monitor the catalytic converter's
performance to ensure low emissions.

--
Jim Yanik
jyanik
at
kua.net

John Horner

2006-09-14 05:38:37 UTC

Post by Jim Yanik
Well,the desired end result is complete combustion(a clean exhaust),and
exhaust O2 content is an indication of how well that's happening.
They are real-time corrections,and measure ACTUAL exhaust output.
(if a plug misfires,or a input-condition sensor is inaccurate,this feedback
corrects for it.it also allows for individual cylinders' injectors to be
corrected,compensating for differing air flow thru the cylinders.They are
not necessarily all equal!)

Uh, hold on there. Few if any modern fuel injection systems monitor
each cylinder and adjust them independently. At best you have one O2
sensor per bank on a multi-head engine. The ECU has no information
about individual cylinders.

I know that some years ago Saab was working on a system which used an
ionization current passed through the spark plug during the exhaust
cycle to try and do the individual cylinder optimization you talk about,
but I don't know if such a thing ever got into production. Certainly
that is not the scheme in use on the majority of vehicles today.

Closed loop fuel injection also does not correct for ignition problems
like a misfiring spark plug.

John

Matt Ion

2006-09-14 05:52:23 UTC

Post by Jim Yanik
Well,the desired end result is complete combustion(a clean
exhaust),and exhaust O2 content is an indication of how well that's
happening.
They are real-time corrections,and measure ACTUAL exhaust output.
(if a plug misfires,or a input-condition sensor is inaccurate,this
feedback corrects for it.it also allows for individual cylinders'
injectors to be corrected,compensating for differing air flow thru the
cylinders.They are not necessarily all equal!)

Well, I can't claim to know exactly how these systems DO work, but I can
hypothesize that it wouldn't be all that difficult for the ECU to get an idea
what's going on with each cylinder individually. Given timing input, it will
know which cylinder is firing when, and a subsequent change in the O2 sensor
reading is pretty easy to correlate to that cylinder.

As O2 sensor input is split up to separate groups of cylinders, as has already
been discussed here, such calculations become even easier...

jim beam

2006-09-14 06:09:33 UTC

Post by Jim Yanik
Well,the desired end result is complete combustion(a clean
exhaust),and exhaust O2 content is an indication of how well that's
happening.
They are real-time corrections,and measure ACTUAL exhaust output.
(if a plug misfires,or a input-condition sensor is inaccurate,this
feedback corrects for it.it also allows for individual cylinders'
injectors to be corrected,compensating for differing air flow thru
the cylinders.They are not necessarily all equal!)

Well, I can't claim to know exactly how these systems DO work, but I can
hypothesize that it wouldn't be all that difficult for the ECU to get an
idea what's going on with each cylinder individually.

it's already done to some extent - angular velocity for each power
stroke is measured, so any cylinder not producing the same "oomph" as
the others gets individually tuned.

Post by Matt Ion
Given timing
input, it will know which cylinder is firing when, and a subsequent
change in the O2 sensor reading is pretty easy to correlate to that
cylinder.
As O2 sensor input is split up to separate groups of cylinders, as has
already been discussed here, such calculations become even easier...

Jim Yanik

2006-09-14 14:11:04 UTC

Post by Jim Yanik
Well,the desired end result is complete combustion(a clean
exhaust),and exhaust O2 content is an indication of how well that's
happening.
They are real-time corrections,and measure ACTUAL exhaust output.
(if a plug misfires,or a input-condition sensor is inaccurate,this
feedback corrects for it.it also allows for individual cylinders'
injectors to be corrected,compensating for differing air flow thru
the cylinders.They are not necessarily all equal!)

Well, I can't claim to know exactly how these systems DO work, but I
can hypothesize that it wouldn't be all that difficult for the ECU to
get an idea what's going on with each cylinder individually.

it's already done to some extent - angular velocity for each power
stroke is measured, so any cylinder not producing the same "oomph" as
the others gets individually tuned.

How does the ECU measure angular velocity? Crank sensor?
That would really complicate the ECU's program and require a much faster
processor.

--
Jim Yanik
jyanik
at
kua.net

jim beam

2006-09-14 14:37:34 UTC

Post by Jim Yanik
Well,the desired end result is complete combustion(a clean
exhaust),and exhaust O2 content is an indication of how well that's
happening.
They are real-time corrections,and measure ACTUAL exhaust output.
(if a plug misfires,or a input-condition sensor is inaccurate,this
feedback corrects for it.it also allows for individual cylinders'
injectors to be corrected,compensating for differing air flow thru
the cylinders.They are not necessarily all equal!)

Well, I can't claim to know exactly how these systems DO work, but I
can hypothesize that it wouldn't be all that difficult for the ECU to
get an idea what's going on with each cylinder individually.

it's already done to some extent - angular velocity for each power
stroke is measured, so any cylinder not producing the same "oomph" as
the others gets individually tuned.

How does the ECU measure angular velocity? Crank sensor?

yes - that sawtooth thing.

Post by Jim Yanik
That would really complicate the ECU's program and require a much faster
processor.

check - and that's what we have! there's a lot of computing power out
there. this stuff is small beer compared to what's in the average pc.

John Horner

2006-09-14 18:26:41 UTC

Post by Matt Ion
Well, I can't claim to know exactly how these systems DO work, but I can
hypothesize that it wouldn't be all that difficult for the ECU to get an
idea what's going on with each cylinder individually. Given timing
input, it will know which cylinder is firing when, and a subsequent
change in the O2 sensor reading is pretty easy to correlate to that
cylinder.

The sensor reaction time is nowhere nearly fast enough to do what you
suggest.

John

Elle

2006-09-14 20:05:04 UTC

Post by Matt Ion
Well, I can't claim to know exactly how these systems DO
work, but I can hypothesize that it wouldn't be all that
difficult for the ECU to get an idea what's going on with
each cylinder individually. Given timing input, it will
know which cylinder is firing when, and a subsequent
change in the O2 sensor reading is pretty easy to
correlate to that cylinder.

The sensor reaction time is nowhere nearly fast enough to
do what you suggest.

Tegger commented not long ago on certain Fords having one
oxygen sensor per cylinder. I googled and found support for
this.

Seems perfectly reasonable to me, timing-wise that the ECU
and O2 sensor could calibrate fuel going to each cylinder.

Jim Yanik

2006-09-14 03:14:19 UTC

"sharx333" <***@gmail.com> wrote in news:***@i42g2000cwa.googlegroups.com:

To add more;

Yes.
The TPS,MAP,IAT,and RPM sensors are all input-side variables,the O2S is the
ONLY output measurement.

If I said this in the first post,apologies.
(it's then just a "senior moment"!) 8-)

--
Jim Yanik
jyanik
at
kua.net

sharx333

2006-09-14 04:08:04 UTC

Post by Jim Yanik
To add more;
The TPS,MAP,IAT,and RPM sensors are all input-side variables,the O2S is the
ONLY output measurement.
If I said this in the first post,apologies.
(it's then just a "senior moment"!) 8-) ...

Wow, Jim, kudos on all the info, you really hit the spot. Thanks!

I'll take a look at "megasquirt", it sounds really interesting!

John Horner

2006-09-13 22:09:43 UTC

Thanks, jim. You make a good point.
I'm really curious about this "open" vs "closed" loop mode. Are we
greatly disadvantaged by always running in open loop? Or are we "lucky"
as TeGGer says? Can't an ECU run in closed loop using just MAP, TPS,
TA, etc sensors?

Closed loop is the way to optimize for low emissions and good fuel
economy. Open loop certainly can work. Most cars manufactured before
1980 were open loop systems be they carbs or early fuel injection.

For those countries where leaded fuel continued to be available the open
loop style carried on for a long time.

John

Jim Yanik

2006-09-12 20:39:44 UTC

Post by Matt Ion
The cat IS essential if your local emissions laws require it!

Actually the emissions laws here *don't* require it.

Fair'nuff... it was more of a generic response to Jim's comment that a
cat is "not essential".

Post by sharx333
I respect TeGGer's responses, but do you guys think he's right on
this one? What if our cars here in the Philippines are programmed for
mileage, instead of emissions as TeGGer says?

I'd suspect it's more likely the various parts were left out for cost
savings, with no regard for emissions OR mileage.

I'd guess that the Honda programmers would only edit/alter their ECU
program enough to ignore a missing sensor rather then write another
completely different one for mileage.

Some adventurous soul here could disconnect their O2 sensor and see if the
ECU then flashes the "check engine" light. A brief test.

--
Jim Yanik
jyanik
at
kua.net

John Horner

2006-09-11 17:03:39 UTC

Post by sharx333
Am I missing something here?? Are our civics "crippled"?

Fuel could also be an issue. In places where tetra ethyl lead continued
to be used as an additive there would be an O2 sensor contamination
issue. TEL was outlawed in the US many years ago, but much of the rest
of the world continued to use it as an octane improver.

That would explain the lack of O2 sensors in countries where the use of
TEL continued.

John

sharx333

2006-09-11 21:34:21 UTC

Post by John Horner
Fuel could also be an issue. In places where tetra ethyl lead continued
to be used as an additive there would be an O2 sensor contamination
issue. TEL was outlawed in the US many years ago, but much of the rest
of the world continued to use it as an octane improver.
That would explain the lack of O2 sensors in countries where the use of
TEL continued.

That could be it! Unleaded fuel was introduced here in 1994, while the
EG line was from 1992-95. Is it true that leaded fuel could damage the
O2 sensor?

If this is the reason, and not cost-cutting, then could I simply, as
jim says, "retrofit" a sensor? (Taking care to use only unleaded fuel,
of course).

The ECU is a P27 (OBD-1 EG JDM Civic 1600 sohc VTEC) which I think is
the same as the one used in the EX US version. However this model has
no VTEC, and no O2 sensor. Could they have left the ECU "as is"?
Wouldn't Honda have used a different ECU code if it's not the same one?
I'm just hoping that it is, since it means I could just plug a new
sensor in.

I'm not after the VTEC, just want to save on gas.

John Horner

2006-09-12 02:56:06 UTC

That could be it! Unleaded fuel was introduced here in 1994, while the
EG line was from 1992-95. Is it true that leaded fuel could damage the
O2 sensor?

Absolutely. Leaded fuels also deteriorate spark plugs, but they are
readily changed. In the days when leaded fuel was the norm in the US,
typical spark plug change intervals were 12-15k miles. Now with
unleaded fuel and slightly better spark plugs the norm is 100k miles.

TEL leaves nasty deposits when it burns. These rapidly build up on
oxygen sensors and ruin it. They also build up in exhaust systems and
on exhaust valves. Oddly enough, the build-up on exhaust valves acts as
a sort of solid lubricant. When the conversion to unleaded happened in
the US, some older cars had very rapid exhaust valve seat wear due to
the lack of TEL's valve lubricating side effect. Other than for exhaust
valves, everything else about TEL fuel is a downside for the motor!

Post by sharx333
If this is the reason, and not cost-cutting, then could I simply, as
jim says, "retrofit" a sensor? (Taking care to use only unleaded fuel,
of course).

You would need someone who really knows the Honda fuel injection system
in detail to answer that. Perhaps you can get your hands on a parts
manual for your version and the US version and try to compare what is
different from one to the other. Maybe it is as simple as connecting an
O2 sensor, maybe not. The US version is certainly capable of running
open loop in the case of a failed O2 sensor.

Do you have any friends in Honda's engineering department :) ??????

John

Jim Yanik

2006-09-12 04:20:46 UTC

Post by John Horner
Fuel could also be an issue. In places where tetra ethyl lead
continued to be used as an additive there would be an O2 sensor
contamination issue. TEL was outlawed in the US many years ago,
but much of the rest of the world continued to use it as an octane
improver.
That would explain the lack of O2 sensors in countries where the use
of TEL continued.

That could be it! Unleaded fuel was introduced here in 1994, while
the EG line was from 1992-95. Is it true that leaded fuel could
damage the O2 sensor?

Absolutely. Leaded fuels also deteriorate spark plugs, but they are
readily changed. In the days when leaded fuel was the norm in the US,
typical spark plug change intervals were 12-15k miles. Now with
unleaded fuel and slightly better spark plugs the norm is 100k miles.
TEL leaves nasty deposits when it burns. These rapidly build up on
oxygen sensors and ruin it. They also build up in exhaust systems and
on exhaust valves. Oddly enough, the build-up on exhaust valves acts
as a sort of solid lubricant. When the conversion to unleaded
happened in the US, some older cars had very rapid exhaust valve seat
wear due to the lack of TEL's valve lubricating side effect. Other
than for exhaust valves, everything else about TEL fuel is a downside
for the motor!

Post by sharx333
If this is the reason, and not cost-cutting, then could I simply, as
jim says, "retrofit" a sensor? (Taking care to use only unleaded
fuel, of course).

You would need someone who really knows the Honda fuel injection
system in detail to answer that. Perhaps you can get your hands on a
parts manual for your version and the US version and try to compare
what is different from one to the other. Maybe it is as simple as
connecting an O2 sensor, maybe not. The US version is certainly
capable of running open loop in the case of a failed O2 sensor.
Do you have any friends in Honda's engineering department :) ??????
John

I believe the ECU would be a different model than a US OBD-I ECU,as a US
ECU will set a code and light the check engine light if the O2 sensor
fails. "not present" counts as "failed".(open)
The Euro ECU's program would have to know to ignore the missing sensor,thus
a different ECU. ECU programming is fixed in PROM,thus a different PROM,and
a different ECU p/n.

--
Jim Yanik
jyanik
at
kua.net

jim beam

2006-09-10 15:33:57 UTC

you're absolutely right.

Post by John Horner
I suppose that it is possible that car makers built open loop versions
for countries without emissions regulations much later than the 1980s,
but I have no idea how it was done or if it is possible to easily
convert such systems to closed loop operations.
John

Jim Yanik

2006-09-10 17:29:32 UTC

Interesting. Early fuel injection systems sold in the US were indeed
open loop designs, such as the Bosch D-Jetronic which was installed on
many late 1960s and early 1970s era Volkswagens and Volvos. Closed loop
came into general use about the same time as three way catalytic
converters did. Late 1970s and onward.
I suppose that it is possible that car makers built open loop versions
for countries without emissions regulations much later than the 1980s,
but I have no idea how it was done or if it is possible to easily
convert such systems to closed loop operations.
John

Corvettes used to have a MECHANICAL fuel injection option(totally open-
loop),long before EFI came to be.

--
Jim Yanik
jyanik
at
kua.net

Stewart DIBBS

2006-09-10 20:46:14 UTC

Post by Jim Yanik
Corvettes used to have a MECHANICAL fuel injection option(totally open-
loop),long before EFI came to be.

Anyone remember the Lucas mechanical FI system? Wonderful when it worked
properly, a pig when it didn't, which was most of the time, being made by
Lucas ...

And some Peugeot 404's had a mechanical FI system too.

sd

Matt Ion

2006-09-10 23:42:56 UTC

Post by Stewart DIBBS

Post by Jim Yanik
Corvettes used to have a MECHANICAL fuel injection option(totally open-
loop),long before EFI came to be.

Anyone remember the Lucas mechanical FI system? Wonderful when it worked
properly, a pig when it didn't, which was most of the time, being made by
Lucas ...
And some Peugeot 404's had a mechanical FI system too.

Look at any old diesel engine, particularly those on tractors and heavy
equipment... mechanical FI there as well.

ajtessier

2006-09-10 22:10:47 UTC