so after I replaced my air change temp sensor my truck started to idle roughly. ive been replacing things to get my engine light off since its been reading bank one and bank two combustion too lean. I have replaced my fuel filter, mass air flow, cleaned and recharged my air filter, ran injector cleaning as well as had my vacuum lines and my exhaust smoked looking for leaks, plus replaced all four of my o2 sensors since the top two were reading high volts while the battery was on and after you would turn the engine over it would go to normal readings while it took a couple minutes for the lower two to even start reading. so I don't think there is anyting left for my to replace other than a bad PCV off the IAC. that's what I think my problem from what I have researched so far but I wanted to get some advice from here. would the PCV be the my idle problem?




1999 ford f150
4.2 v6
k&n cold air

 

Check the compression to see if the engine is healthy.

 

how would I go about doing that?

 

Remove the spark plugs. Disable the fuel pump and ignition. screw in test gauge in each spark plug hole one at a time and turn the engine with the starter to see what pressure builds up.

 

You don't have an exhaust leak, do you? Or an aftermarket PCV valve?

I still suspect a vac leak, or you cold air intake is leaking after the MAF. Go over ALL your connections for vacuum and check the lines behind the battery.

If you are running the air or heat and you accelerate, does the air switch to the defroster vents? That would indicate a vacuum issue.

Remember the code means a lean condition has been detected, so the PCM is making it run richer. If you don't correct it, it can cook the cats.

 

I used break cleaner and I sprayed the back of my engine where my pcv line goes into. My engine reved up so I'm Leaning towards the elbow for the pcv.

 

I had it on my 4.2 a well. PCV vac lines.

 

it was the elbow for the pcv

 

Yeah - mine was bad too. 4k miles later it was showing wear already when I checked it. Keep an eye on it.