Date: 23 Aug 2005 16:02:08 -0700
From: "Mike Deskevich" <mikedeskevichnospaml.com>
Subject: Re: "Throttle body" on 9-5 -- why!?


Gary Fritz wrote: > * Why does Saab have to replace the simple, cheap, near-foolproof > mechanical linkage with an expensive and failure-prone subsystem? The > only reason I can think of is the anti-skid controller, but geeze, wasn't > there a simpler and more reliable way to do it? i think the main reason is emissions. this way the ECU reads from the gas pedal what you want to do, compares that with what the car is doing and then opens or closes the throttle in a way to reduce emissions. if you open the throttle faster than the injectors can keep up, then you'll have lean issues resulting in more NOx and if you close the throttle quicker than you can shut the injectors down, you'll have a rich condition resulting in more HCs (this can easily be taken care of with a damper on the throttle closing, my old toyota has this and it's fool proof). personally, i hate throttle-by-wire. when i drive a throttle-by-wire car, i can notice quite a lag between the time i press the go pedal and the time the car starts going. it makes pulling out into traffice a pain. i guess you'd probably get used to it, but i don't drive throttle-by-wire enough to know. there are simpler ways to handle things like torque limiting,anti-skit control, rev limiting, etc. it all falls under messing with the timing. but i guess they'd rather put some cheap servos on there and chare $500 when they go bad. i just wish you had a choice when you bought a car. i'd order mechanical controls on everything from the throttle to the windows to the door locks. i like stuff that i can fix myself.

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