Burning tables warning

[yngndrw]

Hi,

I've been reading through the MegaSquirt manuals and it keeps warning that you cannot burn the tables while the engine is running:

IMPORTANT NOTE: Do NOT burn tables ('Calibrate AFR Table' or 'Calibrate Thermistor Tables') on a running engine. Even idle is NOT allowed, because these tables ONLY exist in flash, so once a table is erased, there is nothing but garbage in there until it is re-programmed, one word at a time. Until that reprogramming is complete, operating the engine is unsafe.

However I read somewhere that auto-tuned values are only kept while the MegaSquirt unit is powered. If it is powered from the ignition, how are you meant to stop the engine without resetting the MegaSquirt in this case ? I would have assumed that the values would have been kept on the laptop software and you can then burn it after restarting the MegaSquirt, but it doesn't seem to be that way.

Also regarding the AFR table - Am I right in thinking that if there is no EGO sensor then the AFR table is not used at all and can be left empty ? Also that the AFR table is only ever used by the auto-tuner as a target ? Just wanted to check as it seemed a bit unclear.

Thanks,
-Andrew.

[Matt Cramer]

The only tables you can't burn on a running engine are the sensor calibration tables in the Tools menu.

[yngndrw]

Ah okay that makes sense then, thanks.

[kjones6039]

That would apply to the Stim also?

[yngndrw]

I believe the limitation is only to protect the engine from running with undefined settings. As the stimulator shouldn't be able to be damaged no matter what settings are used I can't see it being a problem for it.

[kjones6039]

Gottcha!!