[TELVM]

I'll try to help.

Originally Posted by blownintegra

There is a VE table, and a spark table but i can't figure out the numbers and what they relate to.

To simplify, the values in the VE table represent the amount of fuel MS feeds at a particular rpm and MAP pressure. This is dictated by the volumetric efficiency (capacity of ingesting air) of each particular engine. At low rpm & low MAP the engine process little air and demands little fuel. At high rpm & high MAP the engine process lots of air and demands more fuel. So generally speaking the numbers in the VE table should increase following a 'northwards' and 'eastwards' pattern thru the table, decrease in a 'southwards' and 'westwards' pattern.

You really need a wideband oxygen sensor to tune a coherent VE table. You write a value in a cell (say 1100 rpm & 30 kPa), then test it by putting the engine at that combination of rpm & MAP and watching what AFR the wideband display shows, then correct the value when necessary (a higher number in the cell for richer, smaller for leaner). To begin with in 'fail safe mode' I'll aim to 14.5 from the bottom of the table up to ~75 Kpa, then progressively enrich at higher MAPs until about 12.5~13.2 (depending of engine) at 100 kPa (WOT in NA engines).

Naturally aspirated engines with moderate compression ratios/camshaft timings (the usual street car) can tolerate relatively high levels of error in the AFR setting for some time without serious danger, but only at partial throttle. Above ~75 kPa MAP a too lean mixture can quickly destroy the engine, so start tuning the 'southwestern' zone of the VE table first, staying away from WOT and high rpm, and only venture 'north' and 'eastwards' after you become confident about your tuning ability.

... which is advance and which is retarded?

As the mixture doesn't burn instantaneously after the spark, but needs some (small but measurable) time to burn completely, gasoline engines ignite several degrees before the piston reachs Top Dead Center (TDC, its maximum elevation inside the cylinder). This allows the flame front time to adequately develop for when the piston reachs TDC a few degrees and miliseconds later.

That's ignition advance. When we say 'ignition advance' or 'spark timing' is 20º, the spark is firing when the particular piston in compression phase is 20º short of 360º in angular and a bit short of max elevation in linear. A timing of 22º is 2 degrees more advanced than 20º. A timing of 17º is 3 degrees more retarded than 20º. The more before TDC we ignite, the more advanced the timing, and viceversa.



As happens with the amount of fuel, the engine demands different ignition timing at different combinations of MAP & rpm. This is trickier to tune however, as only a dynamometer or an experienced 'seat of the pants meter' can tell the correct ignition advance. Too much an advanced ignition timing can destroy the engine, so it's safer to begin with lower values and increase only after confidence.

In the Megasquirt Spark Table the number in each cell represents the degrees in ignition advance added to the base timing. So if base timing is say 10º, and the cell value is 17º, the real total advance at that combination is 27º.

Can you tell me a good start for distributor settings ...

Sorry, I'm not familiar with your engine and blind numerical advice could do more harm than good. Read this for advice on ignition advance tuning with MS1-Extra:

MS1 Extra Tuning Manual

Also, same with the fuel?

Read this for advice on VE table tuning with MS1-Extra:

MS1 Extra Tuning Manual

Please note, my VE table is in % not in lambda like yours.

Please note the table I posted above is an AFR targets table (8x8) in volts, not a VE table (12x12) in fuel. Autotune looks at the AFR target table (which we previously fill with AFR targets, expressed as wideband voltage) for reference to correct fuel values in the VE table.

So if for instance the AFR target table commands 'maintain a 14.7:1 AFR at 2000 rpm & 50 kPa' (expressed as say 2.5 volts wideband in the 2000 rpm & 50 kPa cell in the AFR targets table), autotune will automatically correct the 2000 rpm & 50 kPa cell in the VE table with the amount of fuel that yields 14.7:1 as read by the wideband (say 39, or 45, or 61, or whichever for the particular case).

Info on how autotune works: MS1 Extra Tuning Manual


I'll try a search tomorrow to see if I cand find Megasquirt VE and spark maps for a Metro 1.0 like 3-cyl yours.