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Message: <blockquote data-quote="Acoustic" data-source="post: 116937" data-attributes="member: 728">Yes, NO WAY to cheat 20v ECU.Please let me give you another example. This one completely nothing to do with O2 sensor.Battery newly installed, ECU previous memory all lost. When start engine, ECU uses all default values.Scenario 1 - assume vacuum hoses plugged wrongly. I.e. the power steering air pressure supply into power steering rack was not connected to power steering but immediately back to intake plenum box.This will cause the engine to be in constant high idle, since it is blowing extra air into the intake box in a weird manner. You'll have to assume that a human is constantly turning the steering at super speed and caused the power steering rack valve to open full all the time.Since power steering turning will draw heavy load on the engine, this feature was engineered and put in to compensate when parking. It's standard on all engines.OK, back to the scenario. Everyone's idling is 900 rpm when battery newly installed. But my fcuked up vacuum passages made it idling 1,500 rpm.Since I didn't know this and didn't know why, we did allot of "so-called tuning" to tone it down to 900 rpm. But always have drivability problems after that.So after many months, I gave up, don't care even after battery removed and reconnected.It's idle high at 1,500 rpm or so.After 2 weeks of aunty driving it's come back down to 900 rpm.Why?If the ECU is not programmed with high inteligence when I don't know why.Please note - Idle Speed Control Valve - ISCV is not only used to Idling, but driving, full throttle, deceleration also running.It will be an extremely difficult process to fine tune the new MAPs on fully programmable.Therefore I stress to everyone - when you install fully programmable, don't forget about other issues.Don't concentrate on fuel map alone, must consider ignition map heavily, as well as ISC duty cycle allot allot.</blockquote>