Griso/Breva ECU/o2 sensor questions questions

[Spaceclam]

ok.

IM sick of my griso popping. The powercommander doesnt seem to be coming around any time soon.

I think i may have discovered a partial solution to the fueling problem (only in closed loop), but i need some numbers

First, closed loop is determined by RPM ONLY, yes? (As in, if i closed my throttle completely at redline, it would opperate in open loop until my RPM dropped, similarly, if i put it in 6th gear near idle and hit it, i would be in closed loop.)

Second, does anyone know where i could get my hands on a fuel ratio graph, or must i pay to have that done?

Third, at what RPM (if that is so) does the ECU go open loop?

Fourth, for whatever reason, i cant find a part number on my o2 sensor. the only letters i can make out spell "japan". Where can i find information on this sensor? specifically, i am looking for a response chart.

Fifth, let me make sure my understanding is correct.

As you increase the throttle, say up a hill (ie, decrease vaccum pressure) it takes the fuel map, and just shifts it vertically, without modifying the shape of the graph to accomodate the new amount of air, yes?

As in, the graph looks the same, just with every point increased by a certain fixed amount according to the vaccum pressure (or combination of RPM vs TPS) correct?

The RPM at which closed loop ends will effect the complexity/effectiveness of this project, but at the very least, I believe i can get rid of the decel popping for good.

Thanks,
-clam

 

[john zibell]

Clam,

May good questions that I would like the answer to as well.

Have you done everything else to eliminate the decel popping? Set valves, synchronized the TBs, reset TPS with VDS or Axone, and checked the exhaust system for leaks? The easy things should be done before you go to the difficult.

 

[Spaceclam]

My exhaust system seems to be fine, i have not checked the throttle balance or the TPS, as this bike went in for it's break in service about 1300 miles ago, so presumably, the dealer has done their work properly. That being said, i will check it anyway. The valves should also be fine, but i have a few other parts to order so i will throw in some gaskets and check them again myself.

However the reason for this project is two fold.
Not only do i want to get my idle/midrange mixture right, but i also want to be able to deck the cylinders and mill the heads a little later on. I cant do this if my mixture is real lean. There are rich spots as well, and i am hoping that whenever the closed loop cuts out, that lean stuff stops.

 

[GTM®]

Andrew, pop-on-decel has little to do with closed loop per our discussion yesterday.

No A/F data has yet been taken yet from a G11 outside of 100% throttle, which is of course, out of the closed loop part of the fueling. You'd have to pay to gather that data if you want it any time soon.

The 5AM does not use a mass-air flow sensor, so your answer is yes. The fueling is "adjusted" at a preset (timed) value based on sensor readings, however it can/does compensate while in open-loop using the barometric pressure sensor and ambient air temp sensor (in real time) per our discussion yesterday too. Closed-loop is determined largely by throttle position.

While in open-loop, there is a shift in the fueling graph. Closed is different.

Look forward to chatting with you more on this direct e-mail.

 

[GuzziMoto]

I think popping on decel is effected more by the stepper motor then by the O2 sensor. The other thing that I believe contributes is the ECU cutting the fuel, many car ECUs do that so I would expect this one to do it as well (but that is an assumption). You can remove the stepper motor as some have done, or you can put a valve on it as I have done. The valve allows you to turn it on and of as needed (cold starts, etc.). Either way seems to reduce the popping.
Do some research on how an O2 sensor works, you may be suprised (I was). They all work pretty much the same. Wide band Lambda sensors are a whole different kettle of fish and work like you would think a normal O2 sensor works.
If you want to fool the ECU into richening up the mixture, maybe messing with the temp sensor would be the thing. Someone on another board did that with a V11, they put a variable resistor on the engine temp sensor. If your worried about raising the compression and the mixture being lean, remember that is mostly an issue under full or near full throttle loads where the O2 sensor is out of the loop.
I had a dyno operator do some part throttle runs on my Griso and it was lean around 4k rpm, but not much.

 

[GuzziMoto]

About your fifth point, that is not really a good expression of how it works in my opinion. The ECU has a number of sensors that it uses to establish how much fuel is required. The throttle position is one of those sensors, as well as crank position/rpm,air temp, engine temp, air pressure,etc. In my experience (with a Buell as well as my Guzzi) the O2 sensor is closer to what you describe then anything else. The ECU has a map based on the sensors mentioned. It then moves that map (or a portion of it) up or down based on what the O2 sensor says. Now, a good EFI system will alter parts of the map independently of the rest based on the O2 sensor, but it would not suprise me if the Guzzi ECU just moved the whole map.

 

[Nu18F]

Why can't a potentiometer be used inline with the Lamba to trick it and if needed another for the other sensor ?

Thats assuming there's not a built in fuel cut on closed throttle for emission reasons. Come to think of it , is there ?

There's not a secondary AIR system on these engines so it stands to reason there could be .

No gear position switch other than neutral on these , correct ?

FWIW , has this ECM been hacked by anyone yet ?

 

[GuzziMoto]

The O2 sensor is hard to alter. You would have to increase the output of the O2 sensor to get the ECU to add more fuel. There are devices that claim to be able to do that. But I do not have much faith in them because the O2 sensor does not output a steady state voltage, but rather it swings fairly wildly back and forth. The difference between rich and lean with a standard O2 sensor is very small. I have heard the ECU does not measure the actual output but rather count the swings back and forth and average them. I am not an expert on this so you may want to research closed loop fuel injection yourself. Here is an interesting link on the subject.
http://www.moto-one.com.au/performance/ ... p_efi.html
It is more complicated then you might think. And the difference between rich and lean is a very small voltage. Hard to accurately fudge.
Other sensors like engine temp are easy to fudge, but the O2 sensor would likely try to undo any changes you achieved by doing so.

 

[Nu18F]

GuzziMoto - thanks for the link .

I'm not an expert but this sure seems a rather simple matter to just richen the bottom fueling up a little w/o turning the FI light on.


Here is something i've wondered about concerning the two valve Griso ;

Defeat the stepper motor - defeat the 02 sensor

Whats the difference's' between this defeated set-up and the MG LeMans that Power Commander made a USB for ?

I'm going to dig out the wiring diagrams and try to figure it out - emphasis on try LOL

 

[GuzziMoto]

If you can defeat the O2 sensor, you could probably make a PCIII work, but they are completely different ECUs. Richening up the part that is lean requires defeating the O2 sensor to prevent it from leaning that part back out. The link I posted has a neat part down near the bottom where the author defeats the O2 sensor and zeros the ECU (getting rid of any leaning out the O2 sensor may have already done). That sounds like a possibility for our bikes but I'm not sure how you will defeat the O2 sensor with out triggering an error code.
One final thought on defeating the O2 sensor, it is a step backwards not forwards. I would prefer to use something that would keep the O2 sensor but allow me to alter the fueling as needed for best power and driveability. That device, the PCV, is supposedly coming soon. I'm not limiting my options to just that (I have even considered replacing the FI with carbs), but it is my favorite option after my experiences with a PCIII on my wifes V11.