Quote:
Originally Posted by nikitopo
This is why 99.9% of the tuners provide separate tunes per fuel type and set the IAM equal to 1.
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Most tuners will assume if your getting a tune your a car enthusiast and you will run your car on premium grade fuel or the grade fuel that the tune is set for at all times.
If the tuner knows your going to do that they can set IAM to 1 and run the tune at its most aggressive ignition timing at startup.
Stock tunes are set up for the average person who maybe doesn't understand fuel types/grades and will dump in low octane fuel cause its cheaper. ie the manual says it will run on 95 so they use 95 ron cause it cheaper.
Setting the IAM to 0.7 as in standard tune slows a bit more safety margin for people who may run lower octane fuels or countries where premium fuels are not widely available. In this way at each startup the tune is in a less aggressive mode until the ecu detects minimal knock and will advance timing via IAM during driving.
It also makes it easier to do consistent dyno runs as you dont have the iam resetting to 0.7 each time you switch off car or reflash, save you having to do several runs to get iam to 1