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Motec M1 Engine Crank Fuel Volume Compensation - Order of magnitude ?

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The recent cold weather has led to revisiting cold start settings and I wonder if anyone could share the values they are using for cranking trims.

The 09 Cold Start Tuning Webinar mentions the order to address the various M1 tables, cranking enrichment being last, but some idea of the scale of what might be appropriate would be great.

The engine is a Subaru EJ253 NA SOHC with two position intake cams but figures for any engine would be a starting point. Even a guess at the maximum trim for say 0°C and the rate of decline over cranking cycles would be very helpful.

I have found that the default seems to work great. Starts at 200% and tapers off quickly. Here is one example that I think is unmodified:

Attached Files

Thanks David. Really appreciate this as I did not realise there was a default table.

If you download any of the "base migration" packages, you can simply open them in M1 Tune and look at the various tables. Base packages are available for download from here:

https://moteconline.motec.com.au/Package

Thanks David. This will be a great help as I am about to tackle Fuel Film values.

At the moment the engine records lambda values of 1.32 or more accelerating from cranking to initial idle and probably the same higher up.

Hi Rupert,

One driver of the amount of compensation required is the type of fuel that you use. I have found with E85 that the Cranking Compensation when cold needs to be quite high (400%+) but petrol doesn't need as much, more along the lines of the one that David has posted.

With the Fuel Film, definitely load the default settings, and use the Fuel Film Primary Scale to move the whole range up and down until you get the overall operation close to ideal, and then move the separate point in the Fuel Film Primary Main table for fine tuning if needed.

Thanks Stephen.

Following on a bit, I wonder if the Fuel Film component of injection is taken account of in Quick Lambda VE tuning or whether engine load needs to be stabilised for "Q" changes to be valid. I have recently used some Time graph values to modify the VE table and some of the changes look a bit strange, possibly because the engine load was changing ?

I need to tune for various ambient pressure settings in flight so an understanding of how stabilised the engine needs to be for the lambda value to be an accurate component of the VE calculation would be very helpful (load changes tend to lead to climb or descend tendencies as well as gradual engine speed variation).

Hi Rupert,

The "Q", "L" and "W" functions take into account all of the fuelling compensations that are occurring before it applies the changes to the Engine Efficiency table. When I am tuning engines with the M1, and going back through the timegraphs, I tend to avoid using the Lambda Was functions anywhere that the engine state is changing, not due to the interactions of the compensations, but the transport delay for the Lambda sensor can skew the results. I'll look for a place that the engine has been stable for a second or so before making changes.

Thanks Stephen. Very helpful.