Aftermarket Wideband to Rear O2 signal

[Kodename47]

Whatever you do don't take the stock O2 sensor output as what's happening, it won't necessarily be accurate.

How are you reading the AFR of the wideband? Custom map result from the ECU in logs or just the visual display in the car? If it's properly setup you could easily rescale the stock sensor to your wideband output, especially if the wideband in a similar position. Or you could not bother and log the wideband output rather than the front O2. So long as the difference is minimal around the CL area, which it should be, then it won't have much of an impact on fueling error.

[Skorov]

Originally Posted by Kodename47

Whatever you do don't take the stock O2 sensor output as what's happening, it won't necessarily be accurate.

How are you reading the AFR of the wideband? Custom map result from the ECU in logs or just the visual display in the car? If it's properly setup you could easily rescale the stock sensor to your wideband output, especially if the wideband in a similar position. Or you could not bother and log the wideband output rather than the front O2. So long as the difference is minimal around the CL area, which it should be, then it won't have much of an impact on fueling error.

Thanks! So you're suggesting I use the wideband as the point of truth.

I'm looking at the visual display and the custom map result from ECU logs.

Just to confirm, I should do this:
1. Scale the custom map output to match the visual display.
2. (Optional) Rescale stock O2 sensor based in wideband data.

Do I have this right?

[Kodename47]

Originally Posted by Skorov

Thanks! So you're suggesting I use the wideband as the point of truth.

I'm looking at the visual display and the custom map result from ECU logs.

Just to confirm, I should do this:
1. Scale the custom map output to match the visual display.
2. (Optional) Rescale stock O2 sensor based in wideband data.

Do I have this right?

Are the wideband readings different? There should be information/specs about what voltage your sensor/controller outputs so creating the table should be easy, unless it's programmable output. What sensor setup do you have?

[Skorov]

Originally Posted by Kodename47

Are the wideband readings different? There should be information/specs about what voltage your sensor/controller outputs so creating the table should be easy, unless it's programmable output. What sensor setup do you have?

After seeing a rather silly mistake in my aftermarket O2 scaling, I have corrected and now the stock and aftermarket O2 read almost the same.

However, the reading from the ECU is a constant ~0.25 less than the reading on the display. It's an AEM Failsafe gauge.

I might have to just live with it.

[Kodename47]

Originally Posted by Skorov

After seeing a rather silly mistake in my aftermarket O2 scaling, I have corrected and now the stock and aftermarket O2 read almost the same.

However, the reading from the ECU is a constant ~0.25 less than the reading on the display. It's an AEM Failsafe gauge.

I might have to just live with it.

Even at lambda 1? Sounds like the output has a voltage offset or there's something causing interference. If it's always 0.25 AFR different, just change the map by that amount if you're certain.

[Skorov]

Originally Posted by Kodename47

Even at lambda 1? Sounds like the output has a voltage offset or there's something causing interference. If it's always 0.25 AFR different, just change the map by that amount if you're certain.

I've scaled the reading to match the gauge display as much as possible. As you can see from the log below, the readings are a bit off when compared to the stock O2 sensor.

http://www.datazap.me/u/skorov/aem-f...log=0&data=3-6

Do you think this is an acceptable error?

Thanks!

[Kodename47]

Originally Posted by Skorov

I've scaled the reading to match the gauge display as much as possible. As you can see from the log below, the readings are a bit off when compared to the stock O2 sensor.

http://www.datazap.me/u/skorov/aem-f...log=0&data=3-6

Do you think this is an acceptable error?

Thanks!

From that log you can easily see the delay caused by the difference in position. Now you can log the wideband I personally wouldn't worry about the stock one. There will always be a variance between different sensors, and honestly there may be times when the stock one's more accurate.

So long as your closed loop operation is scaled using the OEM sensor to reduce trims, use the wideband just to keep an eye the sensor isn't failing over time.

Remember to try and calibrate the wideband every once in a while. Most recommend annually.

[Skorov]

Originally Posted by Kodename47

From that log you can easily see the delay caused by the difference in position. Now you can log the wideband I personally wouldn't worry about the stock one. There will always be a variance between different sensors, and honestly there may be times when the stock one's more accurate.

So long as your closed loop operation is scaled using the OEM sensor to reduce trims, use the wideband just to keep an eye the sensor isn't failing over time.

Remember to try and calibrate the wideband every once in a while. Most recommend annually.

Awesome! Good to have this finally finished.

I want to use the rear O2 to rescale the open loop portion of the MAF sensor. Any reason why that's a bad idea?

[Kodename47]

Originally Posted by Skorov

I want to use the rear O2 to rescale the open loop portion of the MAF sensor. Any reason why that's a bad idea?

Nope, that's what you should do. To make it more accurate you could set a flat AFR in the fuel table, and if you're using vgi's tool remember to increase the row offset by 1 or 2.

[Fizz]

Originally Posted by Kodename47

Nope, that's what you should do. To make it more accurate you could set a flat AFR in the fuel table, and if you're using vgi's tool remember to increase the row offset by 1 or 2.

Just about to order a UEGO wideband myself.....will contact you soon to get your help in rescaling etc

[Kodename47]

Originally Posted by Fizz

Just about to order a UEGO wideband myself.....will contact you soon to get your help in rescaling etc

Could I recommend the NGK AFX, or it's replacement as it's now discontinued. Better sensors which are likely to last longer and be more accurate.

[Fizz]

Originally Posted by Kodename47

Could I recommend the NGK AFX, or it's replacement as it's now discontinued. Better sensors which are likely to last longer and be more accurate.

Will check them out....

[Kodename47]

Originally Posted by Fizz

Will check them out....

This is basically a replica of the NTK AFX - Make sure you go for the NGK sensor, that is what I was told.

AFR500

Or NTK's replacement for the AFX:
NTK AFRM

[Fizz]

Originally Posted by Kodename47

This is basically a replica of the NTK AFX - Make sure you go for the NGK sensor, that is what I was told.

AFR500

Or NTK's replacement for the AFX:
NTK AFRM

Thanks, but lol at the backorder till June 2015. Anyways I found a very good deal on the AEM UEGO so might jump on that instead...