Definitely not ideal, but if all else was perfect with his truck, I wouldn't be surprised if it still ran "OK", maybe not but I wouldn't be surprised . The wideband will show rich but not extremely rich because the value is an average of 4 cylinders.
For simplicity sake, lets say all injectors matched perfectly in the test above except injector 4 flowing 20% over the others. And our goal was to get an average of 100ml on all 4 injectors.
1. 100ml 2. 100ml 3. 100ml 4. 120ml = an average of 105ml
Since the wideband is after the merger of all 4 cylinders, we only know the average 105ml # . The wideband would show 5% richer than our goal.
So to get down the 105ml to an average of 100ml you would pull fuel back 5% accross the board.
That would leave our test at
1. 95ml 2. 95ml 3. 95ml 4. 114ml
So cylinders 1,2,3 would only be 5% leaner than our goal and bank #4 would be at 14% richer. And at that point the tuner would stop and give himself a pat on the back for doing a good job not knowing 3 cylinders are 5% lean and 4 is 14% rich
I'm just thinking out loud and obviously we would be working with afr's not ml but hopefully that makes sense. Reading spark plugs or a wideband on each cylinder would also reveal the problem.
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