Re: De Tuning Hell / Starved More Like it
First, in no way have I said that "backfiring" was always a sign of a properly tuned engine. Backfiring can also be a symptom of a faulty motor system as well. What I said was, that properly tuned engines frequently snap, crackle, and pop in the exhaust headers (this is not, strictly speaking, backfiring). This is almost a certainty in the VTX, because of the way the ignition timing is set. In a VTX, when you shut the throttle, the ECU retards the timing, on the principle that we want the fuel mix maximally compressed at low fuel flows to promote full burn at idle, and indeed that is important to maintain a smooth idle. However, when the engine is in an overrun state (i.e. when going from a position of relatively high rpm to a position of relatively low RPM), this is exactly backwards - you want to advance the timing a little (light the mix early), to prevent unburned fuel from flushing into the exhaust (and making bang noises, particularly as a working PAIR valve feeds the partially burned mix new oxygen). Note- This suggests that the ECU relies heavily on the TPS sensor to determine ignition table values.
Tapper this does make sense to me; i appreciate your commentary.