Date: Fri, 6 Jun 1997 09:37:02 -0700 (PDT) >From: Erik C Peterson <n9541548@scooter.cc.wwu.edu> To: kenneth d lewis <kdlewis@juno.com> Cc: Multiple recipients of list <vanagon@lenti> Subject: Re: O2 sensor question Message-ID: <Pine.ULT.3.91.970606093621.23470a-100000@scooter.cc.wwu.edu> The O2 sensor is in closed loop while in startup and warmup, then it goes to open loop after the sensor is at operating temperature. Erik Peterson Vehicle Research Institute On Fri, 6 Jun 1997, kenneth d lewis wrote: > Malcom: > I beg to differ. I have a dash mounted LED (O2 sensor) monitor. I have > NEVER seen the system go into open loop once it reaches operating > temperature. In fact the higher the RPMs the faster the lean/rich cycles > occur. > >From the outer banks of North Carolina to the Smokies. > Ken Lewis > 86 VW Transporter Three Door Pickup > > > On Fri, 6 Jun 1997 02:32:51 -0500 mholser@Adobe.COM (Malcolm Holser) > writes: > >since the O2 sensor is usually not in use when driving up high (^; > >You see, the system goes into an open-loop mode. bypassing the sensor > >at something like 3000 rpm and above. Then engines make so little power > > >at altitude that you usually downshift and keep the rev's high. The > >airflow meter, which kinda measures air mass, kinda compensates. I > understand > >the hot-wire versions do a better job. > > > >In closed-loop operation (normal driving) the O2 sensor will do a good > >job of controlling for optimum burn, including compensating for > altitude. > > > >malc: hello a differ a bit .... Sorry when the engine is cold the hego sensor is not working and ignore by the E.C.U {OPEN LOOP} The E.C.U start to read the hego sensor when the hego is warm up] and ecu can see a signal from the coolant sensor the engine start to warm up normaly the ecu gone wait until the hego voltage reach over .6 volts on the hego After come the close loop start to control the emission to keep the best mixture 14.7 to 1 { strochiometric} something like that, ouf big name. At wide open throttle E.C.U ignore hego you need power not the time to control emission A.F.C or Vane air flow measure cubic inch of air and you have air temps sensor inside the vane air flow to ckeck the barometic pressure you have two kind of sensors M.A.P manifold absolute pressure sensing the vacuum in the intake B.A.P barometric presssure outside the motor some of those sensor are inside the ecu depend on the companie Mass sensor or hot wire type calculate the densite of the air more the air is cold more oxygen you have, so you need more fuel more is hot less you have oxygen, you need less fuel for the same cubic foot. this calculated by a cold wire and a hot wire some mass air flow have 200 degree difference betwen those two wires The ecu always try to keep that 200 degree difference so by the current it need to keep that difference the processor know how much air going inside the motor bye Denis Belisle quebec P.S if you see funny words do not laugh please I like better speak then write Next time is gone be in french {joke} I hope its gone help some people on the list .
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