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Closed Loop Lambda

Understanding AFR

Discussion and questions related to the course Understand AFR


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What are thoughts on keeping closed loop lambda activated @ wide open throttle?(or even throughout the entire map) Is it something that is not really accurate due to refresh rates or only possible if using a wideband sensor for ECU control?

It's very dependent on the ECU and how that control is managed. For example on our 86 turbo I use closed loop control continuously. I find the closed loop control fast and accurate so it's very effective at keeping the lambda tracking target. The MoTeC however uses CAN communications between the ECU and the LTC (Lambda To CAN) which includes diagnostic information and if the sensor is deemed to be bad, closed loop control is suspended.

I also use a much narrower control range under high load (+/-5%) compared to what I allow in the cruise areas (+/-15%). At idle where we are much more likley to see the effects of heat soak I allow +/-20%.

I don't personally like the idea of closed loop control on an analogue wideband controller that doesn't offer diagnostic information as the ECU has no way of knowing if the wideband signal is reliable.

Thanks for that Andre, I'll try it out and see how it goes.

Here's a webinar specific to the MoTeC M1 that explains things in much more detail: https://www.hpacademy.com/previous-webinars/124-closed-loop-fuel-control-motec-m1/