Okay so i have a 2000 ford f-150 v6 4.2, a while back she threw a too lean bank 2 code (P0174). I started going down the list, replaced the MAF, air filter, fuel pump and filter, checked for vacuum leaks, nada. Then I get a too lean bank one code (P0171) and and oil leak from my driver side valve cover gasket. Ordered the valve cover & turned my attention towards the EVAP system specifically. Had rough idling, bad throttle response, hesitation, poor gas mileage, and hissing when i opened the gas cap. Went on to replacing the PCV valve, checked gas cap, oil filler cap, and dipstick, all of them were fine. Even did a smoke test and was unable to find a leak. Shortly after that i got an unable to bleed up gas tank code (P1450) and a Cylinder 4 misfire detected (P0304) replaced the purge valve & got that valve cover done as well as ordered new spark plugs. I cleared the codes, but EVAP and CAT are still red on the code reader & I'm not seeing improvement. The only other thing i can think of is injectors, ECU, EGR valve, or vapor canister? if this or something similar happened to yall what was the issue?

 

Those monitors can take a while to run. Lots of variables...

If you have no other symptoms and no CURRENT fault codes, just drive it normally and check the monitor status every now and then.

Have no idea what "improvement" you might be looking for...

 

Lean codes often set when the engine is cold so testing when the engine is warm might not find them. If you can read freeze frame data it will tell you the conditions when the code was set. Live data will also show a lean condition through fuel trims, watch them on a cold engine.

The common lean problem cause for that engine is the isolator bolts.

 

If he still had "lean" codes or the conditions that cause them, the O2 and the fuel monitors would not have executed successfully (which they have per his report).

 

It's for next time. The lean codes will probably be back. He cleared them, and they stay pending for a while before they set. With freeze frame and live data he can do better diagnostic work.

I'm not even sure what codes he's actually looking at. Are you? EVAP and CAT are still red? What does that mean?

 

You probably owe the truck an intake mani gasket and isolator bolts.

Get in line. Everyone with a 4.2 goes through this rite of passage eventually.

I bet the EVAP and CAT monitors just haven’t been set yet.