Ignition Timing State Fluctuations

[glausb23]

Hello,
I am having an issue with my Yamaha R6 engine while it is idling where the Ignition Timing State is constantly fluctuating between "Idle" and "Normal" state and consequently--idle is very choppy and rough. At times, the engine will start to bog down and sometimes even kill. This seems to always happen when the Timing State stays at "Normal" for longer consecutive amounts of time.

Additionally, the live Ignition Timing channel takes on an essentially sinusoidal pattern as the engine idles, constantly jumping between values of ~12.5 to 0 advance. All diagnostic channels report nothing out of the ordinary while this is happening.

Is there a parameter that I need to change somewhere, which will cause the ECU to stay in the "Idle" Timing State and not constantly switch between the two? I'm assuming this is the cause of my engine running poorly.

Any help is greatly appreciated! I can also send a log file upon request.

Thanks,
Benjamin

[Stephen Dean]

Hi,

The Ignition Timing State is going to Normal as the Idle control system is requesting a higher Ignition Timing number than the Main Ignition Timing map has at that point. The Ignition Timing Main table represents the upper timing limit in the M1, so if a function requests a timing value more advanced than the Ignition Timing Main table, it will be prevented from doing so. I normally set the Ignition Timing Main table in the idle region to around 15~20 of Advance to allow for the Idle Control system to operate. If the engine is needing more timing than this I will increase the engine speed using the Throttle or ICV.

The M1 will use Ignition Timing for Idle Control as it is a rapid and effective way to maintain the aimed for engine speed, It is possible for the Ignition Timing to vary from firing at 20ADV to 20RTD in cylinder to cylinder firings as a response to the changes in the instantaneous Engine Speed calculation. For longer term Idle Speed control it will use the Throttle (if DBW) or the Idle Solenoid/Stepper motor control as these are slower in their response to changes.

Idle control calibration is an iterative process, you need to get the engine tuning to a point that it will hold the Engine Speed around the Idle zone without hunting, until this is done then setting up the Idle Control system is pretty pointless. All changes in the Engine Efficiency map around the idle control zone should be gradual and the Lambda should be on Aim. Once the engine is running in a stable condition, then you can tune the Idle Control to maintain the Engine Speed to the Idle Aim.

Are you using DBW on this engine, or and ICV?

[glausb23]

Hello,
Thanks for the help, after reading through what you said, this makes sense. I currently have the main timing table set with values around 10-12.5 degrees advance in the idle speed range. I will increase those values significantly and see if that eliminates some/all of the issues.

This engine is using Drive-By-Wire.

Thanks,
Benjamin

[Stephen Dean]

Hi Benjamin,

With DBW, the Idle Mass Flow Feed Forward table is the core that the control runs on, so this needs to be calibrated correctly. The IMFFF values are a percentage of the Idle Aim Throttle Actuator Maximum parameter, I normally set this value to provide a operating temperature Idle Feed Forward value around the 75% mark, I have found that this then provides enough of a window for the closed loop idle control to work in, as well as being able to open the throttle enough at low engine temps to maintain idle during the warmup phase.

[glausb23]

Hello,
Thank you again for the help on this. For an update:
I have disabled idle control and was able to get the fuel tuned reasonably well within the engine idle speed range. I increased the values in the Ignition Timing Main table to more around ~16-18 degrees in the idle speed range.

I know that the Ignition Timing Main table should be tuned properly before the Mass Flow Forward Feed table is tuned, but I believe our MFFF table may be so far off that we are currently unable to tune Ignition effectively because the engine simply is not running smoothly enough.

Just out of curiosity, does MoTeC have any data on what Fuel Injection Timing parameters should be set at for a Yamaha R6? I'm wondering if poor injection timing is also contributing to the poor idle quality and compounding our issues at this point.

My Fuel Timing Primary Main table is currently set at the following values:
500rpm = 400deg, 2000rpm = 400deg, 3500rpm = 551deg, 5000rpm = 567deg, 6500rpm = 583.5deg, 8000rpm = 607deg, 9500rpm = 610 deg, 11,000rpm = 610deg, 12,500rpm = 610deg, 14,000rpm = 610deg.

Fuel Timing Primary Limit is set to 180 deg

Fuel Timing Primary makeup is set to 190deg for all engine speeds

Fuel Timing Primary Edge set to End of Injection

As always, any help/advice is greatly appreciated.

Thanks,
Benjamin

[Stephen Dean]

Hi Benjamin,

The base Fuel Timing will work for most installations, this needs to be tuned per engine to maximise its operation. The way that this is done is by holding the engine (after it has been tuned) on a load point and gradually increasing the timing from 400 degrees (sometimes you need to decrease the angle from this point as well) until the lambda goes richer, keep increasing the timing until it leans off again and this gives you the window for the optimum Fuel Timing angle. I tend to take the middle of the range as my Fuel Timing when I tune an engine. Once you have done this in a couple of points you should see a pattern forming in the angles, this can then be extrapolated out to fill in the remainder of the table.

[glausb23]

Got it, I will keep that fuel timing tuning procedure in mind later on down the line once the engine fuel and ignition tables are tuned properly.

Are the values that I have currently the base fuel timing numbers that come pre-programmed in M1 Tune? I just want to verify that these numbers are not way off. This tune file has passed through many hands and I want to be sure nobody has changed these values to strange values without my knowing.

I would also like to ask: should closed loop fuel control be activated for the idle speed ranges when trying to tune/setup idle control, or should closed loop be set to operate only at RPM's above the idle speed range?

Thanks,
Benjamin

[David Ferguson]

I suggest you just put 400 in for all RPMs (or eliminate the Engine Speed axis), for now.

[glausb23]

Will do, thank you. Any input on whether closed loop fuel trimming should be enabled in the idle speed ranges when tuning/setting up idle control?

Thanks,
Benjamin

[David Ferguson]

it's OK to "cheat" and have closed loop active, but you must properly setup the Fuel Closed Loop Period table.

To do that, setup a graph with "Exhaust Mass Flow (g/s)", and Fuel Mixture Aim and Exhaust Lambda (same graph/scale). Now hold the engine at different RPMs so that the Exhaust Mass Flow matches the axis values in your Fuel Closed Loop Period table. It's best of the Lambda matches the Aim but as long as it's steady/flat trace, it's OK. While holding that steady, change the fuel mixture Aim by about 5-10 %. You can then Pause the Telemetry Display, go back in time and measure how long it took for the the Fuel Mixture change to show up on the Lambda (ie, the trace becomes flat again).
Repeat for different mass flows. The low values are the important ones for the Closed Loop to work well during idle, and not causing hunting / fluctuations. if in doubt, make the period longer that is better than too short.

Good Luck!