When does the ECM switch from closed loop to open loop mode?

[claydbal]

inthered, if you are correct, then we cant use wideband independantly to monitor afr. i use both the wideband commander a dtt twinscan2 + to monitor on street and dyno.

can you not watch an analog meter ssweeping during a o2 sensor test? indicating switching?

[Paul Goodfield]

Now I'm really confused.
If I got this right, if I increase the bias voltage of the O2 sensors to get a richer afr, they will burn out early or as some of the latest post claim will not burn out early but just be extreemly inaccurate. If I increase the constant of Cubic Inches the sensors will adjust to the afr of bias voltage eventually anyway, so that won't work. The same for upping the VE by percentage, the sensors will adjust to the afr of bias voltage eventually anyway.
So the only way to richen is by voltage bias or go out of closed loop.

If I go out of closed loop I loose adaptive fuel values.

Hey, what happens if I deduce the area of closed loop? Like leaving the idle area in open loop to reduce temps when in idle and/or leave area above 3000 RPM open for power and heat control?

[ViennaHog]

Originally Posted by claydbal

inthered, if you are correct, then we cant use wideband independantly to monitor afr. i use both the wideband commander a dtt twinscan2 + to monitor on street and dyno.

can you not watch an analog meter ssweeping during a o2 sensor test? indicating switching?

For further education on the subject read up http://delphi.com/manufacturers/auto.../switchingoxy/

Delphi calls them switching sensors for a reason as they have a steep signal change at very little variation of the actual oxygen content. This characteristic of the sensor is used by the control strategy of the ECM. E.g. the sensor signals a steep increase in voltage (rich), the ECM responds in a fraction of a second with a reduction in fuel delivery. This will cause a significant swing of the sensor voltage back to lower levels which in turn will trigger an increase of the fuel delivery of the ECM and the game continues. These sensors are cheap and widely used to control emissions in 'easy' applications like motorcycles. Cars with a much more complex control strategy need heated narrow band sensors that cover AFR ranges from say 10-20.

Going back to the initial discussion, both are right in way. The sensors are switching sensors, but the ECM switched the fuel delivery based on the sensor signal.
Clear as mud?

[AZFXSTB]

I love these type of threads!!! Now we need to see a thread on "do I need to remap if I change xxxxx" to bring us back down to normal

[HDMD88]

Originally Posted by AZFXSTB

I love these type of threads!!! Now we need to see a thread on "do I need to remap if I change xxxxx" to bring us back down to normal

There are three major groups of 02 Sensors, there are your wide band sensor, your narrow band sensor and your narrow band SWITCHING DEVICE sensor. As VH said the Harley uses these cheap divices in there Delphi System
Will you shorten the life of the narrow band switching device by setting the CLB table at 800mv....yes.....even the Rocket Scientist told you the richer the mixture is the faster it carbons up and the slower it works.....so what do you think setting the CLB Table to 800mv does, thats right it richens the mixture with very little switching activity so the AFR stays in that rich area for a longer period of time.
Sensors can last 50,000 hours or one hour depending on the fuel, EGTs, location in the system, oil, on/off temps......the 02 sensor is the weak link in the EFI system and needs to be checked frequently.
You can run the CLB table where you want but when your in the 750mv and higher the life of the narrow band switching device will be cut down to about 10,000 miles or so.

[AZFXSTB]

Originally Posted by HDMD88

There are three major groups of 02 Sensors, there are your wide band sensor, your narrow band sensor and your narrow band SWITCHING DEVICE sensor. As VH said the Harley uses these cheap divices in there Delphi System
Will you shorten the life of the narrow band switching device by setting the CLB table at 800mv....yes.....even the Rocket Scientist told you the richer the mixture is the faster it carbons up and the slower it works.....so what do you think setting the CLB Table to 800mv does, thats right it richens the mixture with very little switching activity so the AFR stays in that rich area for a longer period of time.
Sensors can last 50,000 hours or one hour depending on the fuel, EGTs, location in the system, oil, on/off temps......the 02 sensor is the weak link in the EFI system and needs to be checked frequently.
You can run the CLB table where you want but when your in the 750mv and higher the life of the narrow band switching device will be cut down to about 10,000 miles or so.

Doc,

I have heard from little birdies that some tuners toss there O2 sensors after about 6 tunes. My question is if one is using the wideband sensors in a auto AFR system like the Tmax or DDT and the sensors are "showing" calibrated and appear to be reading correctly is the normal deterioration going to richen the AFR over time? The reason I ask is if XXX tuner that knows what they are doing is tossing out the O2s after a few tunes are the rest of us fooling ourselves?

[Paul Goodfield]

I suppose I could help myself from asking such stupid questions but what the hell maybe an answer will help another.

If the O2 sensors are most accurate in the middle of their range (450mv) would'nt make sense (using the TTS) to discover VE values with the bias set to 450mv and then to increase bias to desired value thereafter?

paul

[HDMD88]

Originally Posted by Paul Goodfield

I suppose I could help myself from asking such stupid questions but what the hell maybe an answer will help another.

If the O2 sensors are most accurate in the middle of their range (450mv) would'nt make sense (using the TTS) to discover VE values with the bias set to 450mv and then to increase bias to desired value thereafter?

paul

Paul, no one said the 02 sensors are more accurate at .450mv (at least I didn't) however they are more active there. The Narrow Band Switching Device is accutate between 14:1 to 15:1 AFR, the mv in the CLB table only pick a target AFR in this area. I'd say the accuracy of these sensors to the CLB table are within 20mv or so when they are working correctly.
Using the TTS V-Tune program you have to set the AFR target before yo utune, if you do it the way you mentioned by tuning first at .450mv then setting the CLB to something higher the VE tables will all be off.
Remember the V-Tune uses the 02 sensor to tune with so the target AFR must be set first.

[HDMD88]

Originally Posted by AZFXSTB

Doc,

I have heard from little birdies that some tuners toss there O2 sensors after about 6 tunes. My question is if one is using the wideband sensors in a auto AFR system like the Tmax or DDT and the sensors are "showing" calibrated and appear to be reading correctly is the normal deterioration going to richen the AFR over time? The reason I ask is if XXX tuner that knows what they are doing is tossing out the O2s after a few tunes are the rest of us fooling ourselves?

Your tuner is only as good as his 02 sensors accuracy. When I go to Dealers I take a new wide band sensor with me and my first question is ...''when is the last time your sensor was checked for the correct calibration and when is the last time you changed it out''.
You would be surprised that in 80% of the tuning Dealers are working with a sensor that is anywhere from .5 to 2.0 off the correct calibration.....now the 2.0 is the worse I ever saw but I see .5 to .8 quite often. There are so many things effecting a sensor and it's life span so as a rule I check the accuracy of the sensor every 5 tune ups and replace the sensor every 20 to 25 tunes. If you know of someone that is changing the 02 every 6 tunes he knows about the weak link in tuning and is doing the right thing, however in a production shop like Dealers are every 6 tunes will get expensive this is why I check the calibration every 5 tunes.
Bottom line, the answer to your question is simple....YES, the rest of the tuners are fooling them selves.

[Paul Goodfield]

Originally Posted by HDMD88

Paul, no one said the 02 sensors are more accurate at .450mv (at least I didn't) however they are more active there. The Narrow Band Switching Device is accutate between 14:1 to 15:1 AFR, the mv in the CLB table only pick a target AFR in this area. I'd say the accuracy of these sensors to the CLB table are within 20mv or so when they are working correctly.
Using the TTS V-Tune program you have to set the AFR target before yo utune, if you do it the way you mentioned by tuning first at .450mv then setting the CLB to something higher the VE tables will all be off.
Remember the V-Tune uses the 02 sensor to tune with so the target AFR must be set first.

To be clear I ment still setting the afr to 14.6 for tuning and then setting the bias to 450mv before calculating VE with TTS but as I can see from your response in does not matter since the sensors are accurate over the range you specified.

I guess my concern comes from the v-tune run i did and at the end of the run found engine temps to 248 at idle. To be fair that is with stock mufflers and stock intake but outside temps were only in the mid fifties.

Again you have been very helpful.

[HerkoBagger]

Originally Posted by HDMD88

Your tuner is only as good as his 02 sensors accuracy. When I go to Dealers I take a new wide band sensor with me and my first question is ...''when is the last time your sensor was checked for the correct calibration and when is the last time you changed it out''.
You would be surprised that in 80% of the tuning Dealers are working with a sensor that is anywhere from .5 to 2.0 off the correct calibration.....now the 2.0 is the worse I ever saw but I see .5 to .8 quite often. There are so many things effecting a sensor and it's life span so as a rule I check the accuracy of the sensor every 5 tune ups and replace the sensor every 20 to 25 tunes. If you know of someone that is changing the 02 every 6 tunes he knows about the weak link in tuning and is doing the right thing, however in a production shop like Dealers are every 6 tunes will get expensive this is why I check the calibration every 5 tunes.
Bottom line, the answer to your question is simple....YES, the rest of the tuners are fooling them selves.

Ditto.
I did some sensor tests and comparisons back in the fall that were a real eye opener. It's almost scary to know that many of DJ250i's (and other Dynos too) out there are very likely getting inaccurate AFR data.

As Doc said, we're not talking just a few tenths but some big inaccuracy's. They all seem to work pretty good and maintain a reasonable amount of accuracy near stoic for gasoline. Go richer than stoic...look out! No direct pattern either to the sensors drifting rich or lean when they decide to go incorrect.

There are ways from low budget to high dollar means to check the accuracy of the data.
One of the cheapest and is to chit can the Dyno's sensor every so often and replace it with a new one.

Yes, these sensors have a life expectancy of tens of thousands of miles on a car etc. Even when equated to hours of life, for some reason it's not the case when that sensor is used on a Dyno.

Might be time to add a sixth question?? to Doc's famous list: "5 Questions to ask your tuner"

No. 6: What measures do you take to ensure that your Dyno's AFR measuring device is accurate?

[BVBOB]

Originally Posted by HerkoBagger

Ditto.
I did some sensor tests and comparisons back in the fall that were a real eye opener. It's almost scary to know that many of DJ250i's (and other Dynos too) out there are very likely getting inaccurate AFR data.

As Doc said, we're not talking just a few tenths but some big inaccuracy's. They all seem to work pretty good and maintain a reasonable amount of accuracy near stoic for gasoline. Go richer than stoic...look out! No direct pattern either to the sensors drifting rich or lean when they decide to go incorrect.

There are ways from low budget to high dollar means to check the accuracy of the data.
One of the cheapest and is to chit can the Dyno's sensor every so often and replace it with a new one.

Yes, these sensors have a life expectancy of tens of thousands of miles on a car etc. Even when equated to hours of life, for some reason it's not the case when that sensor is used on a Dyno.

Might be time to add a sixth question?? to Doc's famous list: "5 Questions to ask your tuner"

No. 6: What measures do you take to ensure that your Dyno's AFR measuring device is accurate?

My bet is the sensor's life is shorter due to the lower temps it runs on the dyno compared to being a few inches past the exhaust valve when installed in a bike or auto. A quick easy test if you have dual monitoring is to simply swap sensors(or sniffers) from front to back for a comparison, the Twinscan II has a free air recal feature to use before tuning, pretty hard to say if it would weed out a bad sensor, I believe it just gives it a nuetral starting point.

[HerkoBagger]

Originally Posted by BVBOB

My bet is the sensor's life is shorter due to the lower temps it runs on the dyno compared to being a few inches past the exhaust valve when installed in a bike or auto.

Bob, that's one of the supporting theories along with the condensation that collects with the shut downs and restarts.
Another is the micro copper fragments that get through the filter or with the newer shop air operated vacuum which has no filter.
Stainless sniffer tubes can help here but flexibility is less.

[HerkoBagger]

Originally Posted by BVBOB

My bet is the sensor's life is shorter due to the lower temps it runs on the dyno compared to being a few inches past the exhaust valve when installed in a bike or auto. A quick easy test if you have dual monitoring is to simply swap sensors(or sniffers) from front to back for a comparison, the Twinscan II has a free air recal feature to use before tuning, pretty hard to say if it would weed out a bad sensor, I believe it just gives it a nuetral starting point.

Another can of worms to a degree.
Rigged up a dual sensor test manifold. Had a new DJ sensor on one port and a new LC-1 (free air calibrate-able) sensor in the other port.

Ported through some 13.0 test gas. DJ displayed 13.0/13.1. LC-1 displayed 12.7/12.8. Had a similar situation with the WB Commander a few months prior.

One would think the the DJ was most accurate. Yes, for this 13.0 test. Get a 13.8 gas...may have a different winner.

Basically all 3 use the same sensors.
The differences are in the software and electrics of each the systems. ie the can of worms.
IIRC, TBF mentioned this software/electrics phenomenon some months back.

Then, put a just a few PSI of back pressure on the manifold...more deviations.
It can even go on from here.

[HDMD88]

Originally Posted by HerkoBagger

Ditto.
I did some sensor tests and comparisons back in the fall that were a real eye opener. It's almost scary to know that many of DJ250i's (and other Dynos too) out there are very likely getting inaccurate AFR data.

As Doc said, we're not talking just a few tenths but some big inaccuracy's. They all seem to work pretty good and maintain a reasonable amount of accuracy near stoic for gasoline. Go richer than stoic...look out! No direct pattern either to the sensors drifting rich or lean when they decide to go incorrect.

There are ways from low budget to high dollar means to check the accuracy of the data.
One of the cheapest and is to chit can the Dyno's sensor every so often and replace it with a new one.

Yes, these sensors have a life expectancy of tens of thousands of miles on a car etc. Even when equated to hours of life, for some reason it's not the case when that sensor is used on a Dyno.

Might be time to add a sixth question?? to Doc's famous list: "5 Questions to ask your tuner"

No. 6: What measures do you take to ensure that your Dyno's AFR measuring device is accurate?

John has been working hard on this 02 sensor dilemma, he has spent countless hours documenting figures for me plus he has spent a small fortune in test gasses, LC1 sensors, Bosch wide band sensors, an the latest Dyno equipment to assure a accurate and collective data from every stand point. My hat is off to you for your efforts John.....and.....thanks for the Christmas Cookies, lol.
The best sensors used in todays top performance shops and colleges for EFI map developers cost about $1000.00 and up. These sensors are calibrated at the beginning of a tune for free air and again after lunch....lol...really they are re calibrated for free air most every time they cool down. These kind of sensors are not an option for tuners of our caliber so checking the accuracy of the sensor being used often and replacing the sensor the first sign of it getting lazy is all we can do to assure our tunes will be the best we can give.
Thanks again John for all your research and money you spent in this endeavor.
Doc