Lean on Bank 1 & 2
 

I have been getting the lean on bank 1 code for about a year. But I never saw a change in mpg or anything so I've left it alone. Now my last 5 - 10 tanks of gas I've been getting 12mpg on everyone I normally get 15. Just wondering what do I need to do to remedy my lean on bank 1 & 2 problem which I am hoping is tied to my low mpgs?
The truck is a 97 4x4 4.6L with over 217k miles on it.
The plugs are fine they only have about 20k on them.
Just replaced the inline fuel filter a few months back.
Air filter is clean.
I have cleaned the MAF recently as well.

Thanks.

I'm wondering if you use a fuel system cleaner (injector cleaner)? If so what brand? I have been wanting to ask this question. I don't mean to jack your thread but it could be related. :-X0A6
I heard not to use the cheap stuff. Maybe something like chevron?

I don't recommend fuel system cleaners. I have read articles and watched videos where an independent organization would take several different products and test them on identical cars. Log the mpgs before the treatment and after. They were using dynos to simulate driving & monitor hp. They did like 5 or 6 different brands and none of them made an improvement and a couple actually lowered hp.
I have used Lucas fuel system cleaner to try & get more mpg & get rid of a knock. It didn't do either. I noticed no difference. IMO all it did was make me have to replace my fuel filter sooner.

So any ideas on my Lean engine?

Check the pcv valve tube to where it connects to the intake and make shure it's ok.

maybe its time for some new intake gaskets! that is alot of fine miles hope mine gets there without any problems! OR could just be some vacuum line leaking out! GOOD LUCK!

i would check for vacumm leaks as mentioned above.the pvc hose where it attaches to the back of the intake-90 elbow.check the egr valve for proper opening and closing,make sure the diaphram is working properly,and check the dfpe sensor,could be clogged up, and check lines going to dpfe sensor,mine were clogged as well.hope this helps

ZMAN Let us know what solved your problem.

check for broken bolts on ex. before the cats

I know the PCV hose is fine I have it hose clamped b/c it used to just flop around.
I am pretty ignorant about vacuum systems & the egr system.
I cleaned the egr ports for the famous "insufficient egr flow" code.
So I need a good bit of input to do what ya'll have suggested.
1.) Replace the pcv valve.
2.) Where are the vacuum lines & how do I check them?
3.) How do I "check the egr valve for proper opening and closing, "make sure the diaphragm is working properly",and "check the dfpe sensor,could be clogged up, and check lines going to dpfe sensor"
4.) Should I replace the 2 O2 sensors on the exhaust?
5.) Oh dear gawd plz not replacing gaskets around the intake manifold..... way more work than I want to put into the truck right now haha.

Thanks Guys

have you ever replaced the upstream o2 sensors?? i heard they should be replaced every 80k to 120k. also it might not hurt to check fuel pressure and make sure thats inline.