Did the work above and the truck was running great. Went on a 1,000 mile roundtrip, and immediately upon return, idle began to roughen. Then the check engine came on. Codes are P0174 (System Lean, Bank 2) and P1174 (System Lean, Bank 2). I had both of these codes before changing plugs, wires, and front O2s and thought I had fixed the problem. When I changed the plugs and O2s, the passenger side (Bank 2) was black on all four plugs and the O2.

So my question is....does the rear O2 contribute enough to the injector control to cause these problems? Or could it be something else like the MAF?

 

I'm pretty sure that I came across a thread that said the front and rear O2s should be done at the same time.

 

Most people will say they don't need to be done at the same time, just in pairs (i.e. fronts together and rears together).

 

Anyone else?

 

Did you check for any vacuum leaks? Maybe the MAF but that shouldn't affect only one bank.

 

Good point. I took a quick look, but probably could look closer. Would a leak affect a single bank?

I'm trying to decid if I need to buck up and buy the rear O2's.

 

Change all 4 at the same time. That is your problem. Not sides or front or back. All 4 at the same time.

 

I went ahead and ordered the rears. We'll see what happens when I install them. Fingers crossed.....