So during cruise (2000-2500 RPM), if I reduce my timing and don't change fueling, the 02 sensor reports a leaner burn. Why is this?
If I pull it back 3 degrees. Example: I change it from 20 to 17 deg BTDC, it will change the AFR from 16.0 to 17.0.
I'm just trying to understand the basics of this concept. Anybody think about this before? If the sensor reports a leaner burn, does that mean I've achieved a more complete combustion? I would think that a more complete combustion is desirable....as long as the piston receives peak pressure at the optimum time.
Reducing timing causes a leaner burn, help me understand
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If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0). For tuning/troubleshooting questions, please attached a datalog and your MSQ file to your post.
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
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Reducing timing causes a leaner burn, help me understand
1990 VW Corrado w/ 2.0 16v - MS2extra, V3.0 board, 2.886 code
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DonTZ125
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Re: Reducing timing causes a leaner burn, help me understand
If the sensor is reading leaner, it means there is more oxygen left over. If the amount of fuel hasn't changed, then the only answer is that LESS fuel has burned.
Re: Reducing timing causes a leaner burn, help me understand
Hmmm, I'm gonna have to stew on that.
1990 VW Corrado w/ 2.0 16v - MS2extra, V3.0 board, 2.886 code
Re: Reducing timing causes a leaner burn, help me understand
I believe that less timing allows less time for the fuel to burn. IMO, More advance would allow time for complete combustion at least up to the point of detonation.