I decided to treat my Daewoo Lanos injectors to a professional service & ultrasonic clean. It ran very well before having them serviced but with over 116k miles I thought it would do it good - Big mistake. Fitted the serviced injectors and it ran like a bag of s**te! Idles lumpy, judders when you lightly touch throttle and down on power. Got hold of some injectors from a low mileage Lanos and put them in and the car drives better but was still not as good as it was before I had the original injectors serviced.
Trying various things (which made no difference) I then unplug the O2 sensor and with it disconnected there is a big improvement. The engine sounds better, idles smooth & loads more torque (although lights up the CEL). Now the car drove good before having the injectors cleaned and I've since read that the injectors fitted to these cars don't perform well to being serviced. As it now runs better with the O2 disconnected, is it likely the serviced injectors have also ruined the O2?