If I get my scoot dynotuned is it necessary to remove/deactivate the O2 sensors???

JW

 

No. Why would you think that?

 

If you are getting the bike dyno'd, then the o2 sensors can be removed as they would no longer be used by the ECM. The only time the o2 sensors are used is if the fuel cell is set for 14.6 (which if you're getting dyno'd, it won't be.

you can leave them in and it won't hurt anything.. but I say remove em.

 

Don't know much about them so I thought I'd ask. Simple as that.

 

What are you using to tune the bike with?

 

A lot of this depends on what tuner is used.

I wouldn't remove them. If you make a change to the engine you'll need to re-tune and you'll want the O2 sensors for that.

Lots of discussion about tuning here;

https://www.hdforums.com/forum/elect...-injection-55/

 

I've never heard a single tuner that uses the stock harley o2 sensors. What are you talking about?

If he makes a change and needs to retune, he will NOT need the o2 sensors. The o2 sensors are there to make the bike run as close to stoich as possible when in closed loop. Why would you dyno the bike but still keep and use the stock o2 sensors? That's like throwing money out the window.

Unless you are getting an autotuner with wide band sensors, you don't use the stock o2 sensors when you get the bike dyno'd. You wouldn't use them for anything unless you just running a stock setup.

 

To the OP, no you don't and as a matter of fact I would highly recommend leaving them in.

PowerVision and SERT to name a couple. Both these tuners are reflashing the stock ECM which will ALWAYS look for O2 sensors. The PowerVision even has an AutoTune mode that tunes using the stock O2 sensors.

Totally false. The O2 sensors are there to return a voltage to the ECM. The ECM reads that voltage and interprets it into an A/F ratio. It then compares that A/F ratio to a table that says this is the A/F ratio I should be seeing. If they don't match, the ECM takes note of it and records the data for future fueling tweaks in both the Short Term and Long Term Fuel Trims. If you change the table that holds what A/F value the ECM should be expecting, which is one of the things a tuner does, then the ECM will be looking for a richer value returning from the O2s sensors. Granted the stock sensors are not very accurate outside their limited range, but they will still return values even outside that range. More on this later.

I have a heavily modified Grand Prix that argues what you wrote. This car has so much boost the stock two bar MAP maxes out and I had to install a three-bar and wire it into my tuner just to see how much boost I was running...a car with almost 152% larger injectors than factory, full exhaust from the headers back, cam, massive head work, larger throttle body, bored over, etc. That car still used the factory O2 sensors.

Even though a narrow band O2 is limited in what it can ACCURATLY detect, they are still used by the ECM after a tune. Many make the mistake that they can't detect anything beyond a limited scope but from what I've seen it's not the case...it's just that the further you get from their "Narrow band" the more innacurate they are from O2 reading to O2 reading...meaning a 13.7 A/F on one O2 may read 800 and on another the reading you get is 825.

Some put in spoofers to let the ECM read the same value no matter what but if you properly set up your tune and retain your factory O2 sensors, they can still help adjust fuel trims like they are designed to. You'll use a wideband sensor to dial in your tune then have the ECM look for the value the factory O2 sensors are sending back to the ECM as it's new default A/F ratio.

When getting dynoed you are correct, you run wide bands to get accurate measurements of where your A/F really is. You set your tune there. But once the dyno is done, the ECM is STILL looking for O2 readings so part of that tune is to either set the tune to use spoofers and thus it will never trim the fuel for what the engine is really doing OR you leave the O2s in and let the ECM do what it is supposed to do.

If you have a good tuner, you Long Term Fuel Trims should dial in at 0 and your short terms should be +/- 2. This means the ECM is not having to add or take away fuel (or very little) because the tune is returning the expected reading from the narrow band O2s.

 

Disagreeing with me is one thing, but spreading complete BS about a subject matter is another.

I don't know who gave you the information you are posting, but it's wrong.

Let's look at the following:

1. Stock sensors are narrowband, and are essentially ONLY good to achieve stoich value (14.6). NOTHING ELSE. You can make all the stuff up you want, a fact is a fact. They are incapable of auto tuning anything other than just leaning back out to 14.6.

2. When a fuel cell is set for ANYTHING other than 14.6, the o2 sensors are ignored. There is no way anyone is going to set the afr tables in closed or open loop at 14.6. That's what we are originally trying to get away from. Hence they would not even be evaluated by the ECM for ANY feedback.

3. If you have an "add-on" device, most times you REMOVE the o2 sensors. The reason being is that whatever device you use is tricking the ECM to use the fuel tables it's providing. If the o2 sensors are still there, it constantly try to fight the add on device and lean out the fuel.

A good example of this is how a power commander works (e.g. o2 sensor eliminators)

However, that's NOT what we are discussing here. We are discussing getting the bike dyno'd. When you get a bike dyno'd you are manually telling the engine what fuel to deliver at what RPM, speed, and gear. This is the whole point of a dyno.

Just the fact that you are telling me the stock o2 sensors can be used to auto tune (in the sense that we are talking here) just tells me you have no idea what you are talking about, so I'm not going to argue any further with you.

 

Rather than listening to conflicting opinions here, I'd recommend asking the tuner who is dyno'ing the bike. After all, he is the one doing the work and should be able to tell you:

1. Are my o2 sensors still being used after the dyno?

If the answer is no...

2. Can I remove the o2 sensors?