2000 Express 5.7 Vortec runs rich on Bank 2
September 18th, 2016, 9:24 AM
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2000 Express 5.7 Vortec runs rich on Bank 2
The van is a 2000 Chevy Express, 5.7 Vortec with only 13,000 miles on it.
We have changed plugs, leads, dist. cap & rotor, all filters etc.
We have replaced the spider injectors with uprated design.
We have replaced the HO2 sensors. Comparative compression check was okay.
From OBD live data readouts:
Bank 1 behaves fine. Sensor 1 flicks nicely between 0.1v and 0.9v, LTFT responds typically 3.9 to -3.9%.
Bank 2 starts the day okay, although Sensor 1 does not flick down to 0.1v as evenly as Bank 1. LTFT almost mirrors that of Bank 1.
As time progresses, Bank 2 Sensor 1 sits further from 0.1v, and LTFT increases to 25%. This can eventually cause misfiring, P0300 code (Live data printout attached).
OBD analysis then shows this misfire to be mainly cylinder 4, occasionally cylinder 2. These cylinders are adjacent to each other in the dist. cap, but not firing order. Fault code P0300 is the only code, and can be avoided by revving the engine to clear the soot. Getting about 12mpg (imperial gallon) overall, 18mpg highway.
By disconnecting Bank 2 Sensor 1 and running open loop, van runs much better, but of course is not right. The appropriate codes are shown under this set up.
We have changed plugs, leads, dist. cap & rotor, all filters etc.
We have replaced the spider injectors with uprated design.
We have replaced the HO2 sensors. Comparative compression check was okay.
From OBD live data readouts:
Bank 1 behaves fine. Sensor 1 flicks nicely between 0.1v and 0.9v, LTFT responds typically 3.9 to -3.9%.
Bank 2 starts the day okay, although Sensor 1 does not flick down to 0.1v as evenly as Bank 1. LTFT almost mirrors that of Bank 1.
As time progresses, Bank 2 Sensor 1 sits further from 0.1v, and LTFT increases to 25%. This can eventually cause misfiring, P0300 code (Live data printout attached).
OBD analysis then shows this misfire to be mainly cylinder 4, occasionally cylinder 2. These cylinders are adjacent to each other in the dist. cap, but not firing order. Fault code P0300 is the only code, and can be avoided by revving the engine to clear the soot. Getting about 12mpg (imperial gallon) overall, 18mpg highway.
By disconnecting Bank 2 Sensor 1 and running open loop, van runs much better, but of course is not right. The appropriate codes are shown under this set up.
