Quote:
Originally Posted by tdott
sounds like if a tune is not adjusting to lower quality gas by pulling timing and a stock tune is, wouldn't that mean knock sensitivity is being reduced in the tune? That also makes it less safe, and i'd be very skeptical running that tune if that is the case.
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That depends. Ionic current sensing is only capable of detecting the timing of a combustion event and pressure spike/reverberation (knock) *after* the coil is fired. As soon as the dwell signal is removed, the coil fires, and the mss60 switches the control line over to "monitor" by applying constant voltage to the plug electrode.
So, if the knock is a result of pre-ignition, by definition, the DME can not detect nor correct for it. Additionally, since it's *pre*ignition, pulling timing won't make a difference anyway.
Now, there some other maps than can be adjusted, that can feed into the conditions which set a CC with heavy carbon deposition up for pre-ignition to occur, and those are often modified without much understanding of what they do. There are also differences in some of those maps from one OEM calibration file to another as well as the for fuel quality. Along with knowing what program version (241, etc), it's good to know what OEM calibration your tune is based off of. I suspect a lot of tuners don't actually modify the base file that should be in your car or was read from your car, but copy and send one from a stash of already modified files.