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Marc Haibeck · 10-17-2014

Hi Bennie,

I resolved the problem that I was having with the car that was bogging or stumbling under light loads.

This is what I was seeing in the scan data. When the engine would bog the short term fuel trim would go down to about 90. As if the the fueling was really rich. Then the oxygen sensor voltage would then go to less than 50 mv. This would close the fuel injector and I would see 17 to 20:1 AFR on my wideband oxygen sensor.

If the calibration was set to open loop the car would drive perfectly so the fuel table was correct. I eliminated the problem by replacing the oxygen sensors. New sensors respond quickly to fueling anomalies and don't get stuck down at less than 50 mv when responding to a rich AFR.

10-17-2014	#4
Marc Haibeck Join Date: May 2007 Location: Addison IL Posts: 255	Re: Bogs for a second and then takes off Hi Bennie, I resolved the problem that I was having with the car that was bogging or stumbling under light loads. This is what I was seeing in the scan data. When the engine would bog the short term fuel trim would go down to about 90. As if the the fueling was really rich. Then the oxygen sensor voltage would then go to less than 50 mv. This would close the fuel injector and I would see 17 to 20:1 AFR on my wideband oxygen sensor. If the calibration was set to open loop the car would drive perfectly so the fuel table was correct. I eliminated the problem by replacing the oxygen sensors. New sensors respond quickly to fueling anomalies and don't get stuck down at less than 50 mv when responding to a rich AFR.