Kiwi_Roy Posted December 18, 2015 Share Posted December 18, 2015 Meinolf Please elaborate on setting the CO trim, Do you use an instrument to measure the tailpipe, does it measure CO directly or AFR? What value should you aim for? How do you change the CO trim on the 15M? My old EV has a P8 ECU with a screw, that makes a huge difference to backfire on overrun but I have no idea what it does to the exhaust. Link to comment Share on other sites More sharing options...
Meinolf Posted December 18, 2015 Share Posted December 18, 2015 Hi Roy, this probably needs some background explanations. The 15M is an alpha-n type ECU. That just means that TPS angle (alpha) and rpm (n) are used to determine breakpoints in tables in which values are stored which translate into the opening time of the injectors, which determines the amount of fuel injected. Plus plenty of correction factors, partly in tables and partly as scalars. The basic equation looks like this: Injection time = (Fuel map value + cold start value) x n correction factors. There's one base map which contains the values for the left cylinder and an offset map, which contains the delta, as plus/minus values, for the right cylinder. At the time the 15M was launched no tools existed to download the content of the ECU (=BIN), which is a mixture of program code and data. In fact the ECU code doesn't even support downloading of its content. Beard, the author of GuzziDiag, devised and used a method to get to the data nevertheless. Which, btw, is the reason why the download of a BIN takes ~15min and uploading only a couple of seconds, Now, as with any device an engine is the sum of components, each of which will have tolerances. Adding the tolerances will result in deviations. Now add external circumstances such as air temp/pressure, quality of the fuel, legal requirements for emissions and noise different from country to country, wear of components over time, and so on. The BIN and its values should cover all of this. It's obvious that such a BIN is not tailor-suited to any specific engine. If the tolerances even out then it might be perfect or close to it, but that's rarely the case. So the vendors needed methods of adjusting the values to a specific bike and found 2 methods, One is CO trim and the other one are the bypass screws, CO is equivalent to AFR. So adjusting the CO trim changes the injection time which influences the AFR. On the 15M this can be done with GuzziDiag. The trim values, the range is -127 to +128, are added to be base map values. At low TPS/rpm the base map values are lower than at high TPS/rpm. Adding 1 (CO trim) to 10 (base value) equals 110%. If the base value is 100 then the percentage change is 101%, That's why changing the CO trim has less impact at higher TPS/rpm settings than at lower ones. The bypass screw has the same effect. But instead of changing the injection duration and thus the amount of fuel it opens a path for air to enter. The main differences are that the CO trim affects both injectors/cylinders, the bypass screw only one cylinder and the CO trim is a quantified change, the bypass screw is not (unless you take # of turns as precise quantity) The instrument used for measuring can be a CO tester, I use a AFR logger from Innovate, the LM-2. As the CO trim changes the injection duration of both injectors measuring CO at the tailpipe is ok. On the 15M the CO trim can be changed with GuzziDiag and other programs, As to the value to aim for, that's an interesting question. What do you want to achieve? If it's just the value required by law, take that. Otherwise it get's a bit more complicated. There are some basic correlations between λ, power, emissions and efficiency. Bypassing the emissions, a λ of 0.86 gives best power, a λ of 1.05 gives best efficiency, I have BINs where I targeted λ 0.88 in all areas, that is all of the 256 breakpoints I could reach while logging, and others which are more sophisticated. See here https://db.tt/zptc3hQB The Guzzi engines, in my experience, idles well at any λ from 0.7-0.98. Cheers Meinolf Link to comment Share on other sites More sharing options...
docc Posted December 19, 2015 Share Posted December 19, 2015 As I recall, when we "zeroed" the CO trim on my 15M (with VDSTS), the AFR at the header bungs was 14.7 (theoretically a Lambda of 1.00). Coming from >minus 27 Yet, if the Guzzi would be even happier at Lambda of 0.7-0.98, is there any correlation of steps between the 15M CO scale and expected Lambda change? In other words, if CO trim >zero Link to comment Share on other sites More sharing options...
Gottagetone Posted December 19, 2015 Share Posted December 19, 2015 My TPS breakout harness came in today and I need a bit of help figuring out how to make the readings. I took some initial readings with everything hooked up as it sits meaning I have not backed off the RH idle screw or disconnected the sync rod and choke cable. Here are the readings and settings: With the key on and run switch on: meter set to 2000mv I get a 412 meter set to 200v I get .40 meter set to 20Ω I get 8.07 Key on and run switch off: meter set to 2000mv I get 0 meter set to 20v I get 0 meter set to 20Ω I get 1.17 I know I need to disconnect the sync rod and choke cable and back off the RH idle screw but what setting should I be using on my meter? Should I just have the key on and the run switch off or on? Link to comment Share on other sites More sharing options...
Meinolf Posted December 19, 2015 Share Posted December 19, 2015 Hi, In other words, if CO trim >zero not really. The CO trim changes injection time. The ECU uses the following formula t = (value x multiplier) x 64.5µs. The multiplier, thats a value stored at $B7B3 in the BIN, extends from 0% to 200% ($0-$FF). Assuming the multiplier value in your BIN is 1 ($80), the CO trim value would be t = (value x 100%) x 64.5µs. Then the following formula can be used to calculate Lambda. λnew = (λcurrent x (base map value + CO trim value)) / base map value But that's theory. In reality you will not know what the base map value is at which the engine is currently running. So you need to measure anyway. Cheers Meinolf Link to comment Share on other sites More sharing options...
Meinolf Posted December 19, 2015 Share Posted December 19, 2015 Hi, With the key on and run switch on: meter set to 2000mv I get a 412 that's how you measure. Cheers Meinolf Link to comment Share on other sites More sharing options...
Gottagetone Posted December 19, 2015 Share Posted December 19, 2015 So that 412 should read 156 to 150? Link to comment Share on other sites More sharing options...
Meinolf Posted December 19, 2015 Share Posted December 19, 2015 Hi, So that 412 should read 156 to 150? no 156mV is value to set with the butterfly valve fully closed. Which it is only after disconnecting the rods, screwing out the throttle idle screw and unhooking the cable of the idle lever. Cheers Meinolf Link to comment Share on other sites More sharing options...
Gottagetone Posted December 19, 2015 Share Posted December 19, 2015 I thought about that after I typed it. Ill disconnect sync rod and choke cable, back out the idle screw and then shoot for a 150 to 156, correct? Link to comment Share on other sites More sharing options...
Meinolf Posted December 19, 2015 Share Posted December 19, 2015 Right Link to comment Share on other sites More sharing options...
Gottagetone Posted December 19, 2015 Share Posted December 19, 2015 So I got everything disconnected and the TPS was measuring 397, I was able to reset that and got it to a 154...very touchy to do but I was quite happy to get that number. I then connected the manometer and reconnected the sync rod and left the RH idle screw alone. Started the bike and with some effort was able to balance the TBs. I then adjusted the LH idle screw to show .52V and it brought the idle up to about 2300. I started opening the air bypass crews and it started backfiring into the LH intake and no amount of opening the air bleed screws would bring the idle down. The only thing that brought the idle down was backing way off the LH idle screw to a reading of about .19V. Frustrated....any suggestions? Link to comment Share on other sites More sharing options...
czakky Posted December 20, 2015 Share Posted December 20, 2015 Did you take out the backlash on the synch rod? Link to comment Share on other sites More sharing options...
czakky Posted December 20, 2015 Share Posted December 20, 2015 Also back out that RH idle screw so it's out of play completely. Also usually backing out (opening) the air bypass screws should bring the idle up, correct me if I'm wrong though. Link to comment Share on other sites More sharing options...
Gottagetone Posted December 20, 2015 Share Posted December 20, 2015 Followed the instructions in the FAQ and the ones here to a T. When I set the TPS everything was disconnected and the RH idle screw was backed all the way out...and still is. As I read the instructions once the TBs are balanced you adjust the LH idle screw to where the voltage reads .521V then open up the air bleed screws to bring it down. If this is not the case please let me know what I am doing wrong. Instructions: http://www.v11lemans.com/forums/index.php?showtopic=12204 Link to comment Share on other sites More sharing options...
czakky Posted December 20, 2015 Share Posted December 20, 2015 That's not really what I do. I just use the idle screws for a stable idle, starting around .75-1 full turn out. Balance using bypass screws. Then balance above idle using synch rod (1800-3krpm). Somewhere around 521mv is usually where you end up. Don't worry about that for now though. Good stable idle, well balanced, go for a ride. If you're happy congrats! If not try again, it took me a few tries the first time once you get it you'll be happy... Link to comment Share on other sites More sharing options...
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