Car: 2006 Cobalt SS/NA
Engine: LE5
ECM: E67
The car has a Vibrate 4-2-1 header. The header has the narrowband mounted in the "2" section, so its effectively only reading 2 cylinders. Wideband is placed about 6 inches lower on the downpipe.
Both ECM stoich and wideband stoich are set at 14.7. Fuel trims are within -3%. Narrowband should be seeing a perfect 14.7 that it's striving for. On the other hand the wideband reads at 15.3.
Which one is more accurate? I want to say the wideband, just based on where it's located, although I've heard theories both ways.
Second, if the wideband is more accurate, is the best way to sync the ECM to the wideband by dropping the stoich in the ECM until the wideband reads 14.7?