Ignition settings for cb750 4 cyl wasted spark 2 tach inputs
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Read the manual to see if your question is answered there before posting. If you have questions about MS1/Extra or MS2/Extra or other non-B&G code configuration or tuning, please post them at http://www.msextra.com The full forum rules are here: Forum Rules, be sure to read them all regularly.
Read the manual to see if your question is answered there before posting. If you have questions about MS1/Extra or MS2/Extra or other non-B&G code configuration or tuning, please post them at http://www.msextra.com The full forum rules are here: Forum Rules, be sure to read them all regularly.
Had some weird problems last night, would not communicate with microsquirt after changing the ini file. I had to re-install everything to get it working again??? Anyway, I can put a negative number in now, but doesn't effect it. It will go more advanced with a positive number, just not less advanced with a negative. I noted that the problem would switch to channel one when I tried changing from trigger rise to trigger return? Could it somehow be setting one channel to trigger rise and the other to trigger return?
Don't use trigger return - its only meant for special setups that have the proper wheel. Is it possible to unplug the spark cables and injectors cables, put spare plugs on the plug cables hanging in air, and crank the engine using trigger rise and get the timing for each cylinder - both of which should read 35 deg btdc. If this works correctly, then this might indicate a software problem but could also indicate that the problem is that the motor is accelerating when it fires cyl 2 and then slows as it comes around back to cyl 1. This effect will not be present when the plugs are pulled out because there won't be any explosion. So it might even work without trigger rise - that is give 0 deg adv for both cylinders when using calculated and 35 deg trigger offset. If it doesn't work, then I would double check that the two sensors are really both at 35 btdc.
When you say they are both 35 deg BTDC with trigger rise, is this both on MT and based on a timing light ? If so, can you run 2 short datalogs, one with trigger rise and one with calculated trigger. Let's look at this plus your msq. I will need the latter for bench testing. Unfortunately my power supply finally gave out today and I have to set up a new one, plus complete the testing I am presently set up for.
Here are the datalogs and msq. right now I have carbs on it, so the sensor readings are floating. Is there a way to log the ignition inputs and outputs on both channels?
- Attachments
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- cb750.msq
- msq file
- (25.06 KiB) Downloaded 36 times
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- datalogrisingedge_triggerrise.xls
- rising edge , trigger ise
- (47.63 KiB) Downloaded 22 times
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- datalogrisingedge_calculated.xls
- rising edge, calculated
- (48.39 KiB) Downloaded 28 times
I looked at your data and everything looks ok, so I need to test this on the bench. My new power supply should arrive by Thursday and meanwhile I will set up a test program to generate the inputs you are seeing. I hope to be able to test it this weekend.
The tach inputs are recorded only in the sense that the deltaT column tells you the time between tach inputs. In you case they are all about 200 usec, which is exactly 300 rpm, which is what you are recording. In fact , since you are recording about every 50 ms, I can see(by really blowing up the time vs deltaT plot) a pattern of 4 points corresponding to the first VR and then another 4 points for the second VR, and one of them averages about 500 us less than the other, which translates to an error of less than 1 deg, indicating a sensor placement error of less than 1 deg - which is pretty good. In fact it may be much better - I only looked at one group of points.
The tach inputs are recorded only in the sense that the deltaT column tells you the time between tach inputs. In you case they are all about 200 usec, which is exactly 300 rpm, which is what you are recording. In fact , since you are recording about every 50 ms, I can see(by really blowing up the time vs deltaT plot) a pattern of 4 points corresponding to the first VR and then another 4 points for the second VR, and one of them averages about 500 us less than the other, which translates to an error of less than 1 deg, indicating a sensor placement error of less than 1 deg - which is pretty good. In fact it may be much better - I only looked at one group of points.
OK I tested your msq and i think I know what the problem is. Your setup has the sensor trigger occurring 35-40 deg btdc, which is fine. But there are 2 ways to interpret this:
---------tach1--------------TDC------------------------------------------tach2-----.
tach1 occurs at a trigger offset of +40 deg BTDC, tach2 occurs -320 deg ATDC. For dual spark mode we always want a negative trigger offset, so you should use -320 instead of the +40 or -40, neither of which worked for you. The -320 should work - it worked perfectly on the bench with your msq, with both trigger rise and calculated. Both outputs occurred exactly the same (30 deg btdc in calculated mode based on the table advance of 10 deg) and I was able to make the second output go 10 deg advanced or retarded by setting OddAng = +/- 10 deg.
I know the -320 deg offset is stupid, but there was a reason for it. The original code started with a very robust triggering system where people could put their sensors anywhere and use any kind of advance with any kind of offset. This was a nightmare to code and impossible to maintain with the dual spark system, which was based on a strictly next cylinder firing setup. In fact it sets up to fire 2 cylinders before the actual spark occurs. This allows plenty of time for dwell at high rpm. To maintain the previous terminology for users as well as keeping the code consistent, I left advance offset as it was, but whereas for the original (non-dual spark) system it was best to use a +trig offset (but - would also work), dual spark requires a 0 to negative (ATDC) advance.
If you try to put in -320 deg offset with your present MT ini, it won't allow it, so use the attached ini file which opens up the limits to +/359 deg. This should work for you. I apologize for the confusion, it always confuses me and I have to go through a lot of code checking and testing to figure out what to use. It is on my list to really document all the cases and provide examples that I know work.
---------tach1--------------TDC------------------------------------------tach2-----.
tach1 occurs at a trigger offset of +40 deg BTDC, tach2 occurs -320 deg ATDC. For dual spark mode we always want a negative trigger offset, so you should use -320 instead of the +40 or -40, neither of which worked for you. The -320 should work - it worked perfectly on the bench with your msq, with both trigger rise and calculated. Both outputs occurred exactly the same (30 deg btdc in calculated mode based on the table advance of 10 deg) and I was able to make the second output go 10 deg advanced or retarded by setting OddAng = +/- 10 deg.
I know the -320 deg offset is stupid, but there was a reason for it. The original code started with a very robust triggering system where people could put their sensors anywhere and use any kind of advance with any kind of offset. This was a nightmare to code and impossible to maintain with the dual spark system, which was based on a strictly next cylinder firing setup. In fact it sets up to fire 2 cylinders before the actual spark occurs. This allows plenty of time for dwell at high rpm. To maintain the previous terminology for users as well as keeping the code consistent, I left advance offset as it was, but whereas for the original (non-dual spark) system it was best to use a +trig offset (but - would also work), dual spark requires a 0 to negative (ATDC) advance.
If you try to put in -320 deg offset with your present MT ini, it won't allow it, so use the attached ini file which opens up the limits to +/359 deg. This should work for you. I apologize for the confusion, it always confuses me and I have to go through a lot of code checking and testing to figure out what to use. It is on my list to really document all the cases and provide examples that I know work.
- Attachments
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- megasquirt-II_2883.ini
- (106.88 KiB) Downloaded 29 times
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Bernard Fife
- Super Squirter
- Posts: 1009
- Joined: Mon Feb 16, 2004 3:15 pm
Al,
There is a bit on setting the trigger negative in the manual here: http://www.microsquirt.info/dualspark.htm but I will expand and clarify it using your posts. I will also edit the default INI to match your changes.
Lance.
There is a bit on setting the trigger negative in the manual here: http://www.microsquirt.info/dualspark.htm but I will expand and clarify it using your posts. I will also edit the default INI to match your changes.
Lance.