I had an engine code for bank 1 & 2 running lean. I have replaced the PCV valve, all 4 02 sensors, cleaned mass air flow sensor, cleaned the throttle body. Then yesterday I replace the fuel filter (it was nasty) and after I put the new one in the motor now has a very sluggish start up and at idle it chugs. When I put it into gear it chugs even more, and it has barley any get up and go when i step on the gas. I have no idea what it could be at this point. I appreciate any help I can get. It is a 2000 F150 4.6 V8

-PFC Bray

 

Back track your work, perhaps you corrected one concern and induced another. I say this not trying to be sarcastic, stuff just happens. Example, I had a small coolant leak, turned out to the the nipple for the bypass hose (rotted thru-pin hole). This was on my wifes 96 Explorer 5.0, I had to remove the air cleaner duct from filter to throttle body to gain access to the upper hose and t-stat area. Upon reassembly, I failed to fully engage the MAF connector, 2600 miles later the engine started to buck while under load with no CEL activity. Knowing the connector for the ECT was is question, I checked there first. No luck, drove last 200 miles to get home avoiding the interstate and finally at home backing into my drive to unhitch the travel trailer engine stalled. Upon restart it would surge at idle and basically ran like s**t. Another inspection and still no codes being thrown I touched the MAF connector, low and behold, engine quit again, Fully engaged the connector until it locked into place and all is well. After 50 years of twisting wrenches, anybody can make a simple mistake.

 

I am thinking exactly what you are at this point, because it was running good (better but still lean) after I cleaned the MAF sensor and did the Od sensors and PCV. But right after I put the new fuel filter on it S**t hit the fan and thats that. when putting the fuel lines back on is there just one click over the lip on the male ends of the filter or is there another click or something to distinguish it as being locked in?

 

If you get a chance pull out the injectors and see if there is junk in the fuel rails. My 4.2 was having nearly the exact same issue. At some point someone put a MAF housing out of a 4.6 (which is aluminum instead of plastic) and the CAI was just complicating things further. So check little things like that. Maybe you have a leak behind your MAF. That would certainly cause both banks to show a lean status.

 

would it possible be a leak where the air intake meets the throttle body? I am pretty new at this stuff and just trying to learn the ropes on this truck.

 

(crazy guy yells in the background) - FUEL PUMP !

 

Check your fuel pressure. Aside from that I'd suspect a possible intake manifold gasket leak.

 

would it possible be a leak where the air intake meets the throttle body? Normally intake leaks are referred to as being after the throttle plate, but with MAF located upstream of throttle body, I don't know, lets see what others say.

 

There is a valve cover breather line on my 98 that looks pretty sketchy - right up before the throttle body, it runs from the drivers side valve cover to the rubber intake, there is some loose feeling rubber elbows at the ends, inspect for leaks/cracks. Also I had just replaced the rubber hose on the PCV valve, turns out it was sucking flat. Do a bit of leak checking with some carb cleaner while its idling. Don't forget to check fuel pressure, A failing pump can cause all sorts of weird problems.