Originally posted by boosted60trimrst
thanx what do u tune for cruising in boost . also why is it spiking to 21.0 after i let of the gas completly . i let off the gas rpms start dropping and when it get down to 2500 it spikes to 21.0 everytime and stops spiking when is drops down to 1500rpm

When you let off the gas while still in gear(engine braking), the ECU cuts all fuel flow from the injectors by switching them off. This conserves fuel while declerating. When you have slowed down enough, the injectors kick back on as usual. This is why your wideband is reading super lean...its all o2.

At part throttle boost you may see it be lean, or close to stoich(14.7:1), because the ECU is staying in closed loop, trying to adjust the A/F to 14.7:1. I never really had any problems with the A/F like that in low, part throttle boost,but i wouldnt run more than 5-7 psi like that. Just floor it if you want more boost. The TPS sensor will see full throttle, and the ECU goes into open loop, not correcting the fuel mixture anymore. The ECU roughly goes into open loop mode at 75% or more throttle position. This issues is exactly why i love the Megasquirt..full control of open/closed loop, A/F, timing, ect..