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Hi, this may be a stupid question and will probably show my ignorance as I am new to this tuning caper.

If I play a log session whilst viewing the history tables set for BLM history average, can I use the calculated average once the log completes running as a guide on adjusting the VE tables.
Eg: If the log gives a value of 104.998 at 1800rpm and 50 map, should I then increase the VE table at 1800 rpm, 50 map by 4.998% ?

I assume that if the the BLM is > 100% it is adding more fuel and if < 100% it is taking fuel away.

Thanks

spot on!

although if its that far out i wouldn't bother changing it by so fine an amount, ie. multiply by 4.9 and then once you get to like 101.347 or something then go to finer calc detail.

also something to note, some of the adx's out there show the blms as 100% = 128 .... this needs to be converted if you want to use it as a multiplier of 100% .... the $12P is done as a percentage of 100% so you can steal the calc out of it if you want to use it one others that arn't.

Thanks for the reply.

I will have a play and see if I can get the BLM's tighter. What are the limits of adjustment the ecm can make on the BLM's ?

im not sure but i've seen some up around 15% so theres plenty there!

Not sure what code your using, but in 12P there are two items to control the BLM limits ...
BLM Params - Block Learn - Maximum Allowable BLM
BLM Params - Block Learn - Minimum Allowable BLM

In most standard cals (not just 12P) they are usually 140 and 110, so around +10% and -15%. Tuning to BLMs works ok just make sure your VE table looks ok and does not have big peaks and troughs, also be aware of skewed oxygen sensor readings at low RPM if you have a largish cam.