Ignition Timing State Fluctuations

[Stephen Dean]

The base numbers in the Fuel Closed Loop Period table should work for most engines on the market, as they where developed on a Subaru EJ20 with the turbo in the standard location and the lambda sensor in the downpipe. This means that on most vehicles the lambda sensor will be much closed to the heads so the changes to the lambda will occur before the next sampling occurs.

[GWRMOTORSPORT]

Hi Stephen
jumping on this thread, is it worth spending time on the Fuel Closed Loop Period table if the
engines vary from N/A lower reving V8 to a high reving 4 cyl Japanese bike engine,
What is the most important information to consider when deciding to configure this table
1 engine RPM range?
2 measurement of exhaust valve to lambda sensor distance, collector or header sensor position?
3 N/A or turbo?
I know we should all configure all the tables in the M1 but the majority of customers won't spend
the 100's or possibly 1000's of pounds or dollars for dyno time to do them all, or is this one table that
should be a priority.
If not is there a simple rule were I could have say 3 or 4 Fuel Closed Loop Period tables that could
cover most engine configurations.

Thanks
Steve
GWR Motorsport

[Stephen Dean]

Hi Steve,

The most important measurement is the transport time, i.e. how long it takes a change in the lambda being requested by the M1 to it actually being read. I haven't found an easy formula or method to determine this value based off of physical measurements that does a better job than just doing so quick tests when the vehicle is on the dyno and calibrating the table that way.

I feel that there are too many variables in play to determine it empirically, even running a muffler or not makes a difference to the number on my car.

[glausb23]

Hello all,
I am circling back to this thread after doing some more research into the idle control system in M1 Tune and trying to get a better understanding of how all of the parameters work together to control and maintain target idle aim.

One parameter that I've discovered which I haven't heard anything about in previous webinars, forum posts, etc. is the Engine Crank Fuel Volume Compensation.

I understand that this value is meant to correct for the additional fuel required due to poor air/fuel mixing at low air speed during cranking. I'm wondering if the current values in my package are drastically off and contributing to the hard-start issues we're having while trying to tune this Yamaha R6 engine. Is there a method to calculate good starting point values for this table when starting a new engine tune from scratch?

Here are the current values left over from a previous engine using a variation of my current package:

Engine Crank Fuel Volume Compensation.JPG (83.73 KiB) Viewed 5761 times

Do these seem reasonable? I am essentially at square one in tuning this engine (recently fixed an air leak in the intake system, so going back through to start re-tuning the efficiency map with this leak fixed).

As always, any help is greatly appreciated.

Thanks,
Benjamin

[David Ferguson]

That is too much extra fuel when already warm. I suggest you start by copying the entire table from one of the migration base maps. Don’t touch that until your Efficiency table is tuned in idle and you’ve extended the trends down toward cranking RPM.

[glausb23]

That would explain at least in part--why the engine always fires right up when cold, but warm/hot starts are a struggle. I took the values from "Generic 4 Cylinder, MAP based Efficiency Migration Base" Version 1.01.0009 for a GPRP package in February 2016 (1.01)

Just curious, I would assume these values are developed for a 4-cylinder car engine of much higher displacement than this Yamaha R6 (600cc). Should I subtract an offset from all of these values to account for that, or should they be ok to run for the time being until the efficiency map is tuned?

Thanks much for the help!
Benjamin

[Stephen Dean]

Hi,

That Package was developed on a Subaru EJ20 (2.0 litres) but the M1 will compensate for the engine capacity in the Engine Displacement parameter setting. These are also a percentage trim, so it is a extra percentage of the Fuel Volume calculated from the Engine Efficiency table, so if this isn't correct, then everything downstream of this will also be incorrect.

The Engine Crank Fuel Volume Compensation that I run in my car has a quite large number (over 500%) for the first cycle (even larger for E85), and then it rapidly comes out with successive cycles. My engine will usually fire on the first cycle irrespective of the temperature or how long the car has been sitting.

Each engine requires a different Cranking and Post Start Fuel Volume Compensation table, this is an iterative process to get it configured correctly.