The Bullet Board

As I continue to try to understand this mapping stuff I wonder... What is the definition of "closed loop" operation with the stock ECU? Is it defined by a fixed chunk of the map - e.g. rpm range of xxxx-yyyy and throttle position of xx%-yy%? If so does anybody know where that is? Or are there other variables that enter into it? Just wonder when the ECU thinks it's time to pay attention to the O2 sensor.

When it's in closed loop with the stock narrow band sensor, would be determined by the MAP sensor on the throttle body really. At what combination of throttle position , rpm's and manifold pressure the ECU see's from those sensors , and where the programmers set it to occur. Closed loop operation is based on engine load. Closed loop comes in during light engine loads and cruising. At idle and when at operating temp it should be in closed loop. At a light , fixed throttle position it should be in closed loop. But when you crack it open or you just stay in a wide throttle position , with the engine under high load, it should not be in closed loop. EXACTLY where and when these change over's occur under ever condition the engine see's ? You would have to put a data logger on the bike.

Ok, so the MAP enters into the equation - I can understand that. What piqued my interest, in some of my shopping around I noticed the Powertronic thing retains use of the the narrowband sensor in a "standard" installation. Just for giggles I asked their tech support email how it was used. His response (delivered in less than couple hours) was...

At part throttle, PowerTRONIC operates in closed-loop along with the stock ECU

More than 50% Throttle it overrides the stock ECU and improves performance controlling both Fuel and Ignition

So this seems a little simplistic, but what do I know!

Yeah ? I would say they are right, in very simple terms. The PC-V... same thing. You CAN use it with the stock narrow band sensor. I never did it ? I never wanted that lean of an AFR ? And I'm not sure if it would just ignore the fuel corrections in the cells on the PC-V that may be in there , and just work off the narrow band trying to make it 14.7:1 ? OR ... if it would try to richen the mixture based off of what's in those cells.

I guess that's the root of my question. And I still don't know the answer - if the stock ecu is in closed loop and says "oh no, I'm running too rich" and starts taking out gas, does the piggyback ECU just get to ignore it and say f off, I'm doing what I want and going to do what the map says... It's confusing as the individual points in the map would have a different effect depending on whether it was running in CL mode at the moment or not. But I'm thinking - even if the piggyback ECU adds more fuel per it's map, the stock ECU is still going to keep giving less and less until it drives it back lean enough to satisfy it's 14.7 AFR. So in the end you've gained nothing to keep the narrowband sensor in the system. I guess that's probably the bottom line. But maybe the Powertronic is programmed to ignore/disable the O2 sensor at some point defined by their programmers. Maybe I'll ask Dynojet how they treat it.

I'm overthinking this again. It certainly is easier to understand when the stock O2 is cheated out so the ECU never thinks it needs to cut back fuel to drive it lean.

Haha ! I'm a big over thinker myself. And I hear you. It is interesting stuff. And I agree with your bottom line , when it's all said and done. Whatever the STOCK ECU is going to do , based off of the inputs from the sensors ... we want to intercept and say NO, make it THIS. Really a simple solution to a complex system when you think about it ? Your taking this speed density stock programming with all it's complexity with look up tables and Kilo pascals and etc. And just saying NO ! Haha! At THIS throttle position and THIS RPM I want it at 13.5:1 NOT 14.0:1 !! And all the way down the line. With these tuners, It's really taking a Speed Density system based on manifold pressure and converted into a air fuel ratio, and simplifying it into a ALFA-N system based on simple throttle position and RPM.

I think it would be a good question to ask Dyno jet about the the interaction with a stock narrow band. I think it's kinda of a new thing for them to do ? ... because they have to ,due to EPA crack down and etc. All the PC-V's I have seen in the past , with the Enfield's and other bikes , had the o2 cheaters. And I suspect the way they are tuning bikes now ... with the stock narrow bands.... would be to tune only outside of closed loop. And on their canned maps , you would only see changes in those area's. I THINK.. if they made a change in a closed loop area ? Say they added 20 % fuel in a closed loop area, that might bee too much of a change for a stock narrow band to correct back to 14.7:1 ? So they leave it alone.. That is what I suspect anyway.

Ok, I did send this question into Dynojet...

Can you explain the operation of the power commander V (specifically for Royal Enfield - PC # 27-001) with the stock O2 sensor left installed? What happens when the ECU goes into closed loop mode? Does the PC know, and how does it respond?
Thanks,
Steve

Here was their reply...

Hello Steve,

With the PCV and factory O2 sensor installed (recommended), the vehicle controls and monitors AFR in our low RPM low throttle area while anything outside of this closed loop area, we are able to make fueling changes and optimize the bikes performance. This method will give us the bets of both worlds for fuel economy and performance while still being compliant with emissions laws. If you have any other questions, please let me know.

Thank you,
Danny Boardman
Powersports Technician

So... it has a bit of a feel of... they can't advocate running without it, probably for the same reason they don't send out a cheater anymore. I'll send him a follow up of some variety.

Yup. I got the same feel from them last year when I called them. Seems like a pretty generic answer to me. Hard to pin the guy down to a hard answer when I spoke to him. A little different question for me at the time... but yeah, pushing the narrow band stock sensor use. That's probably how they are approaching tuning all new and near to stock bikes with minor changes I imagine. It still really doesn't answer the question of what would happen if one were to use the stock narrow band sensor, coupled with a canned map that was made with the o2 cheater installed. Changes are made down there in small throttle openings and low rpm's. My gut tells me if that was done ? The stock narrow band sensor would peg to too rich and continuously try to lean it out..

A bit more dialog...
Danny, thank you for the reply. So if the stock ECU is operating in closed loop, anything that’s in the PC-V fuel map is effectively ignored? When attempting to tune & modify the map, how can you tell where the closed loop region is so you know where to attempt optimization and where to not waste effort?

Also, does closed loop operation ignore any information in the ignition timing map?

Thanks,
Steve

Hello Steve,

Not ignored but it will be overwritten by the ECM and that is why we do not make changes in this area. To know where closed loop and open loop are, you can download one of our maps and anywhere there is a zero, will be closed loop.

Thank you,
Danny Boardman
Powersports Technician


They did send me a new map which evidently is the one they now ship with the 27-001. Not much in the fuel map, it's literally all zero's through 60% throttle/5250 RPM - so this is evidently what they consider the closed loop area. Then mostly single digit adjustments in the table beyond that. Interestingly, the ignition table has adjustments pretty much through the entire range.

Yeah , interesting for sure. Good info , thanks for that swamp. I did notice with PC-V maps for other recent model bikes, a similar thing with no fuel corrections made down low in the rpm ranges. Believe it was on my sons Honda and Yamaha crotch rockets ? It would be interesting I think for you to give that new map a test run with the stock o2 , compared your other maps with the cheater in place.