Wideband O2 and MS

Question for the experienced Mega/Microsquirt folks on here - how long do you run with a wideband O2 sensor?  Do you leave it in forever, or do you keep it for the first month or so for tuning, and then pull it?  Or something in between?  And if you do pull it, I assume you put a narrowband back in its place??

I'm mostly wondering because it's the last thing I need to install and run the wiring for and I'm not sure if I should be planning for this to be a permanent part of the car or not. 

I'd leave it in permanently and let the MS run closed loop off it. They'll last a good amount of time if left powered.  The narrowband is really good for sensing stoich at idle, but if you have AFR targets that are anywhere else you'd be better off with the wideband.

The one thing you do not want to do is shut down power to the heater/controller and leave the sensor in place. That will kill it.

Leaving it in permanently is best, that's what all the OEMs are doing nowadays.

Instead of a NB sensor for feedback, just stick with the WB.  If you are worried about it breaking (which is reasonable), find an output switch on the computer that has some temperature input, so that you wait for a specific amount of time before turning the WB on.  Like 5 seconds @70F and maybe 20 seconds @20 F.  That should prevent the sensors from cracking due to water vapor in the exhaust stream.

alfadriver said:

If you are worried about it breaking (which is reasonable), find an output switch on the computer that has some temperature input, so that you wait for a specific amount of time before turning the WB on.  Like 5 seconds @70F and maybe 20 seconds @20 F.  That should prevent the sensors from cracking due to water vapor in the exhaust stream.

Interesting, I'm going to try this next time I put a fresh sensor in my car.

GameboyRMH said:

alfadriver said:

If you are worried about it breaking (which is reasonable), find an output switch on the computer that has some temperature input, so that you wait for a specific amount of time before turning the WB on.  Like 5 seconds @70F and maybe 20 seconds @20 F.  That should prevent the sensors from cracking due to water vapor in the exhaust stream.

Interesting, I'm going to try this next time I put a fresh sensor in my car.

Not being an MS person, is there an output that can be controlled with a simple starting temp vs. time?  Or some variable output signals?  Put that into a digital relay, and then let the relay run the O2 sensor.

The other thing- can you delay going closed loop on the MS based on the sensor giving you a reasonable input?

I know it's possible to trigger switches from a wide selection of factors including engine temperature, many people hook up fan switches to run from engine temperature for example. You can set a range outside of which you get an O2 sensor error and the car goes into limp mode, and I know you can limit the AFR correction to a certain range on the stoichiometric scale just to keep you from blowing up your engine based on faulty O2 readings. I don't remember if you can specifically delay closed-loop mode based on AFR reading range.

In reply to GameboyRMH :

Have you ever recorded the AF signal you get when you go from sensor off, to on, to it working?  It would be even better if there was a signal from the O2 sensor that it's reading right- that's how we do it- just go closed loop as soon as the sensor tells you it's ready.

alfadriver said:

In reply to GameboyRMH :

Have you ever recorded the AF signal you get when you go from sensor off, to on, to it working?  It would be even better if there was a signal from the O2 sensor that it's reading right- that's how we do it- just go closed loop as soon as the sensor tells you it's ready.

Probably not, I generally start logging at or close to full operating temperature and I had the WB02 system wired to power up in ON mode, so by the time the engine fires up the controller is already passing values through from the sensor. Apart from putting out some calibration values in the first few seconds of being powered on, I don't think the Spartan Lambda 2 does anything unusual. I also have it set to stay in open-loop mode until it's close to full operating temperature, so the sensor would be fully warmed up by then. It does have a temperature indicator LED that shows if it's too hot/too cold/just right based on flash patterns, wiring that into the ECU might be useful.

I've got mine permanently installed in my car.

Some of the AEM have a "startup value" that is below the threshold voltage. Not sure of any good way to use it with MS. There is an option to delay O2 correction after start, at least on some of the /extra code versions. May only be on MS3 but I see it often. I set mine for 60 sec to make sure the sensors are warm after startup. There are also limits for O2 correciton range (won't correct if too lean/rich and a fault condition is likely).

I have been using the same NGK wideband and sensors for almost a decade on my personal car.  The only time I wouldn't consider full time use is if you use race fuel with lead content, it can make the sensors die quickly. 

The O2 sensor should be positioned so it will not get blasted with water.

You should not use a short bung that places the sensor directly in the exhaust stream.

Your O2 controller should not be powered up if the motor is not running. RTFM

I power the O2 sensor from the fuel pump relay.

Your tune should be close enough that it will run without the WBO2.

The WBO2 correction is just a trim to compensate for fuel differences, ambient weather, and minor tune discrepancies.

YES! leave the WBO2 in place, a MS1 or 2 system does not have a check engine light so being able to see a gauge is beneficial. O2 correction is a good thing [tm]. 

A narrow band sensor is a switching sensor and does not provide a linear output over any range of O2 levels, it is designed for rapid switching from low to high for systems that regulate AFR by being out of balance (which constantly switch back and forth from lean to rich).

alfadriver said:

GameboyRMH said:

alfadriver said:

If you are worried about it breaking (which is reasonable), find an output switch on the computer that has some temperature input, so that you wait for a specific amount of time before turning the WB on.  Like 5 seconds @70F and maybe 20 seconds @20 F.  That should prevent the sensors from cracking due to water vapor in the exhaust stream.

Interesting, I'm going to try this next time I put a fresh sensor in my car.

Not being an MS person, is there an output that can be controlled with a simple starting temp vs. time?  Or some variable output signals?  Put that into a digital relay, and then let the relay run the O2 sensor.

The other thing- can you delay going closed loop on the MS based on the sensor giving you a reasonable input?

How are you guys identifying a reasonable input? If everything's working fine, that's easy because the sensor is reporting what you expect to see. But if you have a problem and the car is running lean or rich, how much time do you give it before you flag it as a problem?

bentwrench said:

Your O2 controller should not be powered up if the motor is not running. RTFM

I power the O2 sensor from the fuel pump relay.

Mine is also wired to the fuel pump relay...which comes on when the key is in the ON position (as with most cars), so you can still end up spraying moisture at a preheated sensor (a very bad thing) if you leave the key in the ON position for more than a couple seconds before starting a cold engine. I'm thinking it would be better to have a delay timer or perhaps switch it on based on engine temperature.

On an MS system the fuel pump is controlled by the ECU and only comes on for a second or so when the key is turned on to prime the fuel system.

The fuel pump should NEVER run beyond that on a EFI system that is a major safety issue. If the motor is not running the fuel pump should not be running either, period.

Many sanctioning bodies also have this mandate in their rules. All OEM systems are also designed in this manner. Even OEM carb systems with a electric pump are controlled by oil pressure.

bentwrench said:

On an MS system the fuel pump is controlled by the ECU and only comes on for a second or so when the key is turned on to prime the fuel system.

The fuel pump should NEVER run beyond that on a EFI system that is a major safety issue. If the motor is not running the fuel pump should not be running either, period.

Many sanctioning bodies also have this mandate in their rules. All OEM systems are also designed in this manner. Even OEM carb systems with a electric pump are controlled by oil pressure.

Yeah you're right the run-time is limited before the engine starts, so that will limit pre-heating.

Keith Tanner said:

alfadriver said:

GameboyRMH said:

alfadriver said:

If you are worried about it breaking (which is reasonable), find an output switch on the computer that has some temperature input, so that you wait for a specific amount of time before turning the WB on.  Like 5 seconds @70F and maybe 20 seconds @20 F.  That should prevent the sensors from cracking due to water vapor in the exhaust stream.

Interesting, I'm going to try this next time I put a fresh sensor in my car.

Not being an MS person, is there an output that can be controlled with a simple starting temp vs. time?  Or some variable output signals?  Put that into a digital relay, and then let the relay run the O2 sensor.

The other thing- can you delay going closed loop on the MS based on the sensor giving you a reasonable input?

How are you guys identifying a reasonable input? If everything's working fine, that's easy because the sensor is reporting what you expect to see. But if you have a problem and the car is running lean or rich, how much time do you give it before you flag it as a problem?

Remember, all of our sensor hardware is totally internal.  So it tells the system that it's ready.  I know that same signal is within the O2 sensors that are commercially available, as they all work the same way.  But I doubt it's being transmitted at all.

GameboyRMH said:

bentwrench said:

Your O2 controller should not be powered up if the motor is not running. RTFM

I power the O2 sensor from the fuel pump relay.

Mine is also wired to the fuel pump relay...which comes on when the key is in the ON position (as with most cars), so you can still end up spraying moisture at a preheated sensor (a very bad thing) if you leave the key in the ON position for more than a couple seconds before starting a cold engine. I'm thinking it would be better to have a delay timer or perhaps switch it on based on engine temperature.

So to clarify the actual problem- it's not actually spraying water onto a hot sensor, it's actually the heater reaction to that which cracks the heater.  When you start seeing OEM systems that are on and alive at key on, that's what they are fixing.  And that is coming, for sure.  Which is pretty cool to have closed loop fuel control right off of crank.

And then the comment about powering via the fuel pump- good idea when it's over 70F outside.  Bad idea when it's below 40.  It takes a few seconds longer to warm the exhaust over the dew point the colder it gets....

That being said, I can honestly tell you that over the hundreds of times I've done cold starts from -20 to over 100F (and by cold, that's the car at whatever ambient it is, 8 hour soak), I've never broken an instrumentation O2 sensor.  And it's not as if they are that great.  

My O2s last in daily driver use right up to the point the engine sucks a quart of oil because I stretched the oil change out too long.  That reliably kills a Bosch sensor, at least one controlled by Innovate electronics.

That was certainly a lot more answers and info than I was anticipating!  Short answer sounds like I should leave it installed, so all the details of powering on/off I'll have to digest separately...

bentwrench said:

You should not use a short bung that places the sensor directly in the exhaust stream

Can you clarify this?  I was planning on just pulling the existing O2 sensor and screwing in the new wideband.  But I'd guess that would put the tip something like 1/4" into the exhaust pipe.  That no good for widebands?  Should I run one of those spark plug anti-fouler adapters? 

NorseDave said:

bentwrench said:

You should not use a short bung that places the sensor directly in the exhaust stream

Can you clarify this?  I was planning on just pulling the existing O2 sensor and screwing in the new wideband.  But I'd guess that would put the tip something like 1/4" into the exhaust pipe.  That no good for widebands?  Should I run one of those spark plug anti-fouler adapters? 

Yea, I missed that part- can you clarify why you think the sensor should not be in the direct exhaust stream??  We do as much as we can to put it right in the path, and do some CFD to make sure it's equally capable of seeing all cylinders.  The only packaging restriction we have is that the sensor points down- either slightly at an angle or directly down- to make sure water runs off.

If it were me, I'd do my best to put the sensor as far in as possible, so that it can do the most accurate corrections of the fuel.

Paul_VR6 said:

 There is an option to delay O2 correction after start, at least on some of the /extra code versions. May only be on MS3 but I see it often.

Just checked on my MS3X, there is an "EGO delay after start" option.

In reply to alfadriver :

Innovate says so.

There may be something going on with their heater control circuit to where the sensor will overheat easily.  Certainly, if you install one in a factory close-coupled location (like, for instance, the turbo outlet elbow) the sensors die a rapid death.  It's the same sensors as VW screwed a couple inches from the exhaust ports on many cars, so it's not the sensor's fault, it's the controls.

Also, I hate my MTX-L.  It does nothing for 30 seconds as it redoes its warmup procedure every time voltage dips below 12v.  My LC-1 gave readings within 5-10 seconds of power-on, and it stayed powered up like that, so I could datalog a cold start (or any start, for that matter)

In reply to Knurled. :

Thanks for that information- as that means I'll not get an innovate system for my Alfa build.  I had suspected that they don't build the highest quality components, anyway.