vacuum leak

[91fox]

After a quick stomp on the gas peddle the engine definitely is "searching" as it's settling back down to idle speed

 

[91fox]

Just decided to look at trims again, and this is what I saw. Is this due to the pcm commanding the maximum amount of fuel because of the lean codes?

 

[MrBlargMan]

Just decided to look at trims again, and this is what I saw. Is this due to the pcm commanding the maximum amount of fuel because of the lean codes?

View attachment 37289

Yes. The PCM is dumping as much fuel as it can to compensate, and it is still not enough. Thus your lean codes.
Based on those fuel trims, you either have way low fuel pressure, or there is definitely a vacuum leak.
If your EVAP purge valve is hissing, replace it. It should not be doing that.

 

[91fox]

I thought fuel was an issue with this thing as well... A couple of months back I replaced the fuel pump with a delphi brand pump... I've changed a lot of parts on this thing and have yet been able to figure out what the actual cause is.. I guess I'm going to have to go buy a pressure tester and see what type of pressure I've got, I just looked at the pcv elbows on the drivers side bank, one of them is dry rotted, so ill replace it but I severely doubt that's the cause... I don't hear any exhaust leaks, I smoked the system and cant find a vac leak.. so I'm utterly at a loss as to what's causing this issue other than possibly the purge solenoid ( but I don't know how to confirm that it is indeed failed)

 

[91fox]

Could someone educate me as to what all of the vacuum lines behind the drivers side front tire do and if those could have any correlation to the codes that I'm currently experiencing?

 

[MrBlargMan]

Just a heads up, those Delphi pumps are shit. I replaced 3 of them in my Expedition over 2 years. I finally got sick of it and put in a nice AEM 340lph pump. No issues since.

If you are spraying break cleaner or carb cleaner around all of the hoses and intake and are not detecting any kind of vacuum leak, I would be checking your fuel pressure next.

 

[91fox]

^ exactly what i just did, still need to test fuel pressure

 

[Hamfisted]

Is your purge valve solenoid still hissing? Or did you replace it?

 

[91fox]

Im getting it in the morning, it had to be ordered, I'm also going to buy a fuel pressure test kit tomorrow to check out the pressures. Finally I'm going to take of the throttle body and inspect it... Not really sure where else to turn, I dropped the spare tire today to make sure the canister hoses were connected and not leaking and everything appeared to be fine. The issue is still present however, when I quickly snap the throttle the engine seems to stay revved up for longer then normal and then it gets real choppy when trying to idle out, however it only seems to do that one out of every four attempts. Needless to say, it's awful strange.

 

[Hamfisted]

Ok, well put the new purge valve solenoid on and give it a chance before you tear the throttle body off. How's the throttle body look inside? Fairly clean, no carbon/soot build ups ?