Air-Fuel Ratio

[Arata]

The reason I asked about the Catara Sensor is, that is what is used in the Dynojet O2 sensor, that made it relevant.
Is the 99.99% of cars use narrow band sensors accurate??

The difference between the Dynojet "Power Commander and the Motec and the AEM, is a Power Commander plugs into the exsisting ECU using OEM connectors, simple, and costs between $329 and $399 Retail, whats that about 10% of the Motec?
They are not made for cars yet, just Motorcycles.
But just as Dynojet started making Dynos for motorcycles and now does Car Dynos, you can bet a Power Commander for cars is down the road, at a price and ease that anyone can afford and do.

 

[sjs]

The reason I asked about the Catara Sensor is, that is what is used in the Dynojet O2 sensor, that made it relevant.

OK, sorry, I wondered what it had to do with most cars.

Is the 99.99% of cars use narrow band sensors accurate??

If you interpret my original statement of “99.99% of all cars” as referring to cars on the road today, then yes. If you count all cars sold in the past five years then almost certainly still yes. Just 2003 model year? I would say still yes if the new sensor type mentioned above is excluded, and probably yes anyway. There are an awful lot of cars sold each year and I think if you spot-check the most popular models you won’t find many equipped with a wideband, but admittedly I have not checked myself.

The difference between the Dynojet "Power Commander and the Motec and the AEM, is a Power Commander plugs into the exsisting ECU using OEM connectors, simple, …

The AEM plugs directly into the stock connectors, and it monitors all the stock sensors plus many more if your wish to add them.

…and costs between $329 and $399 Retail

Admittedly cheap, but then it doesn’t do nearly as much as the AEM needs to do on a car, and a VTEC angine at that. For a street price of < $1300 the AEM is at least equal value.

They are not made for cars yet, just Motorcycles.

Which makes them somewhat irrelevant to us, though interesting so I’m glad you shared.

But just as Dynojet started making Dynos for motorcycles and now does Car Dynos, .

Frankly their dynos are nothing to brag about except that they are relatively affordable and reasonable consistent from run-run if not terribly accurate. Or perhaps most operators bump things up a bit to please their clients, who knows.

…you can bet a Power Commander for cars is down the road, at a price and ease that anyone can afford and do.

They may be in a crowded field by then but I hope they do get into it. However, as others have already learned, ECUs are not all created equal and some are tougher to hack than others. Not to mention that for cars I suspect they are considerably more complex which means the prices won’t be the same as for the cycles.

 

[BryanZublin]

Originally posted by Eddy (snip) Recently, I was researching around and found that Denso/Toyota has came out with a new wide band sensor (they called it "Air Fuel Ratio Sensor") used in late model Toyota, Honda, Subarus, etc. Unlike the duel cell (one being the pump cell) design, it's a single cell design (which means it uses 4 wires instead of 5). (snip)

Eddy, do you have a link or other info you can post regarding this new wideband O2 sensor?

 

[Eddy]

Denso hasn't really announce this sensor to the general public. It was presented probably more to car manufacturers. In any case, here's a paper on the sensor design by Denso. From reading all the information, it sounds like Toyota was the one who wanted this sensor created and Denso just happens to be making it.

Btw, this paper is a scientific paper so it may be a little tough to understand.

http://www.denso.co.jp/DTR/vol7_no1/dissertation5-i.pdf

There links are training material for Toyota service people so it's probably easier to understand. The last link is particular interesting because it compares the regular Zirconia narrow band sensor to the new Toyota/Denso wide band sensor to the old Titania narrow band sensor.

http://www.lindertech.com/docs/j_thornton_toyota_wraf_sensor.pdf

http://www.autoshop101.com/forms/h37.pdf




Eddy

 

[BryanZublin]

Eddy,
Thanks for the links, it makes for very interesting reading. I found a press release from Denso regarding the sensor:
www.globaldenso.com/ENVIRONMENT/e-report/1999/pdf/11.pdf

It mentions Toyota first using the wide band sensor in 1996 and an improved version in 1998. Considering that it has been in use for more than 5 years by an OEM, I am surprised that it has not appeared in any aftermarket wide band meters. The control cicuitry looks simpler than the 5 wire NTK and Bosch LSU4 sensors.

Do you know which Toyota/Lexus models use this wideband sensor from Denso?

 

[Eddy]

I am not 100% sure but according to those training materials I posted, it should be used in the late model Camrys.

Denso Aftermarket told me that Subaru uses it. I am not sure of the model but the part number is 22641AA00A and it's supposed to be about $130 retail. Btw, Denso will be selling this sensor as an aftermarket generic part soon.

As for Honda, I found that all the late model RSXes and the Civic Si uses this sensor. Also Accord 4 cylinder uses this new sensor 36531-RAA-A01 as well and it's priced at about $120 retail, the cheapest I've found so far.

Denso told me that Toyota sells the sensor at a whopping $300 a piece so shop carefully.

The electronics is easier yes, but the control is not. I have found a few papers from Denso and Toyota and all of them describe the new electronics with an addition of a microcontroller to control the heater which has to be driven using PWM using close loop feedback from the sensor element. It also senses and controls the voltage differential across the terminals to maintain it at 0.3V. There is a risk of overheating the sensor if a microcontroller isn't used.

Eddy

 

[BryanZublin]

Originally posted by Eddy (snip)The electronics is easier yes, but the control is not. I have found a few papers from Denso and Toyota and all of them describe the new electronics with an addition of a microcontroller to control the heater which has to be driven using PWM using close loop feedback from the sensor element. It also senses and controls the voltage differential across the terminals to maintain it at 0.3V. There is a risk of overheating the sensor if a microcontroller isn't used.

Since most air-fuel-ratio meters will already have a microcontroller for display, serial interface, etc., the incremental cost is low once the firmware is worked out. Can you post the links to the technical articles that describe the controller? Thanks in advance and thanks for your previous posts.

 

[Eddy]

Actually they are patents I found. Go to the US Patent Office web site and do a search on "air fuel sensor heater control" and you should find a few.

Eddy

 

[spdntckt]

Perhaps a dumb question, but i was under the impression that most fuel injection systems run in open loop during WOT, and only use the O2 sensors as feedback during normal cruising.... I believe most turbo cars run like this anyway - using MAP and RPM as inputs during WOT.

does the NSX system actually measure O2 at WOT and change the mixtures over time?

also - any good threads on teh differences between ODB I and II?

 

[sjs]

Perhaps a dumb question, but i was under the impression that most fuel injection systems run in open loop during WOT, and only use the O2 sensors as feedback during normal cruising.... I believe most turbo cars run like this anyway - using MAP and RPM as inputs during WOT.

does the NSX system actually measure O2 at WOT and change the mixtures over time?

Not dumb questions at all. As you suspected, the NSX like all cars using narrow band O2 sensors, operate in open-loop mode under hard acceleration and high loads. The exact combination of conditions that trigger a switch from closed-loop to open may vary between car models (throttle position, MP/MAF, etc.), but essentially it happens when the desired A/F is outside the useful range of the sensor. Since the sensors are heavily centered on 14.7:1 for emissions and economy, under hard acceleration and high load it must relinquish control to the primary maps and sensor based trims or the mixture would be dangerously lean and power would suffer.

As for learning, it is generally believed that many ECUs track long-term averages in closed-loop mode, and then apply correction factors throughout the range on the assumption that either the engine, environment, or fuel supply has changed. There may also be short-term "trims" applied globally. I've never seen a definitive paper on it an of course it would vary between manufacturers and models.