Hello, I have a 2016 Silverado with a 5.3l. The engine is stock with stock injectors. Something I noticed while tuning is mostly when the ETC is under operating temp, while coasting the engine will drop to a 10ish afr for a few seconds then go into DEFCO 22.0 afr. Is there any setting to change so it will at least go back to stoich instead of wasting gas? All the posts I seen with a similar issue says its due to bad injector data. Any other settings that could fix this?
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Mine does it too and I don't care at all. They are all like that from the factory.
Why are you commanding a 14.8 AFR anyway with a 9.8% alcohol content too, that isn't right. Stoich needs to match the fuel in the tank.
My personal opinion is that the rich to lean thing it does won't make any notice difference in fuel usage. I can see your really low coolant temp being a factor though, these LT engines do like running at or above 200 degrees.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
Thank you for your response!
There is a way to force DFCO immediately after letting off the throttle. Never tried it on a truck ECU but I would think it would work the same.
Engine > Fuel > Oxygen Sensors > LTFT Idle Cells Thresholds > Enable VSS & Disable VSS >>>> Set Enable to 255 and Disable to 256
I'm assuming some changes in the airflow model cause the ECU to delay entering idle cells for DFCO to be met. Not really sure why honestly, but this has fixed a few of the cars I've tuned where they had a delay entering DFCO. You issue COULD also be that your MAF values, right after the throttle closes, are too high. But give the above a try and see if you like the results.
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