I had my uim crack and hydro lock my engine at 100000 miles, changed all the gaskets, fixed that. Now I'm at 114000 and constantly have have a check engine light for lean bank one. Any ideas. I've already changed out the MAF sensor

did you change the lower too, alot of times lean codes are vacuum leaks. check fuel pressure?

I replaced the upper and lower. And the fuel pressure is good.

mostly just leaves vacuum leak

That'* what I'm afraid of, I was getting a code for a vacuum leak, and it took me forever to figure that one out, now I just get the lean bank one code. I'm going to try and change the injectors out

Check your EGR flex pipe. They are know to crack and leak, causing a nasty code such as yours.

the injectors are almost never a problem. and when they are you get misfire codes. thats why i said vacuum leak, there are tons of spots prone to leaks

I am having the same problem with my 99 Park Ave. I replaced the fuel injectors and nothing changed. Save your money, keep looking for the vacuum leak. I have been doing some research on introducing smoke into the intake manifold and watching for it to escape thru the leak. if I am able to find the leak I will post it hear.

Mike, have you had any luck finding your leak? I found that the bolts had backed out on the UIM I installed 3 or 4 years ago. Some of them were only finger tight. I removed the fuel rail and re-torqued the bolts and the problem went away.

Code can be misleading, to some......makes you think the odd numbered side has the leak.....but since this only has one O2 sensor for fuel mixture, it'* related to the whole engine.....

As the guys have said, yes a vac leak can cause a lean condition, but that is only one of many.....

Problem could be the O2 sensor signal(harness grounded) or a bad sensor, itself....

Fuel.....low fuel pressure or bad injector....contaminated fuel...

An exhaust leak, especially at the "doughnut"....

You say you changed out the MAF...just recently(if yes, new?)? If you have a scan tool and can observe pre O2 data, see if the lean condition is gone with the MAF disconnected.....

When you took apart the upper plenum, did you remove/replace the PCV valve? Have you checked to see if the black and orange o-rings are in place?