So, on our 2003 H2, 161,000 miles, I replaced the fuel injectors.

I replaced the right bank a few weeks ago, but didn't have the fuel line tool, so I ordered one and just did the left side today.
In the two weeks between I probably drove 100 miles or so.
No error codes in the 2 weeks I was driving it, I checked for them after I test drove it the first time, and before I replaced the left side.

I didn't use AC Delco injectors but a brand that RockAuto had listed as a replacent and had good reviews on other sites, Yiksai I think.

Pulled the fuel line from both sides, the return also and replaced the Orings also, replaced the left side injectors, and put everything back together. Hummer hasn't run this good in a long time.

Took it for a 10 mile drive, got Rich Bank 1 and rich Bank 2 suddenly,

Puzzeled why I didn't get a Rich Bank 2 when I replaced the right side but not the left.

Any idead??

 

are you sure the injectors have the same flow rate as the original gm's do as they might be flowing more fuel then what the ECU is programmed for.
things you can also check for is a dirty throttle body not allowing sufficient air in at idle making the mixture rich or a dirty mas air flow sensor throwing the readings out of spec.
look at your long term and short term fuel trims to diagnose your symptoms further.

 

bronxteck has given sound advice, he knows what he is talking about I would follow his lead on your troubleshooting

Neal

 

rodger that, will check to see what I can find