wideband O2 in crossover pipe

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bgroves2908
MegaSquirt Newbie
Posts: 1
Joined: Thu Aug 29, 2013 1:29 pm

wideband O2 in crossover pipe

Post by bgroves2908 »

In the quickstart guide, EGO subsection, it says you can mount your O2 sensor in the crossover pipe. This surprises me. I would have thought there would be a considerable lag in the EG composition in the crossover as opposed to the straight pipes under changing conditions (sudden WOT, etc.). Possibly as much as 2-3 seconds for the crossover to catch up, a hell of a long time to an ECU. Logical or not? Expert opinions, please.
Bernard Fife
Super Squirter
Posts: 1009
Joined: Mon Feb 16, 2004 3:15 pm

Re: wideband O2 in crossover pipe

Post by Bernard Fife »

bg2908,

It may surprise you, but the flow rate of the exhaust, pumping across the crossover due to exhaust pulse timing, diffusion rate within the hot exhaust hot gases, and averaging of the EGO reading within the code make this a complete non-issue.

It is one of many areas where 'gut feelings' lead you down the wrong path.

Another example is thinking that a longer MAP sensor tube will delay the MAP signal significantly (the MAP signal travels at the sped of sound, so an extra 10 feet would only result in a ~0.001 second delay - negligible for most purposes).

Lance.
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