vacuum leak

[91fox]

Hey everyone, so i'm still getting p0171 and p02197 (lean codes) I just replaced the intake manifold gaskets and the tuning valve o'ring (smoke checked and confirmed they were leaking). Everything is reinstalled, and the codes just now came back.. I can hear and audible hiss and smoked the system once more, no smoke visible. (I introduced the smoke from the vac line going to the hydroboost). Wouldn't you know it... the hissing sound seems like it's coming from that area, with the engine running, leading me to believe it's either the purge solenoid or the booster. When I step on the brakes and hold the pedal the engine wants to stall. My question is, is this normal? Can a faulty booster through engine lean codes? Thanks in advance,

 

[Hamfisted]

Yes it can throw a lean code and might be big enough to stall the motor with a leaky brake booster. That's a pretty big vacuum line.


https://www.rockauto.com/en/catalog...56,brake+&+wheel+hub,power+brake+booster,1884

 

[91fox]

Update: So I went back out there and determined the hissing sound is coming from the hose going to the solenoid from the intake manifold (4.6l) so i replaced the hose, and the new hose is still making the same hissing sound. The sound is drastically muffled when i put my hand over it (very close to the solenoid end) i'm not sure what to make of it... it sounds like its really pulling some air from the solenoid or vise versa.

 

[Hamfisted]

Are you talking about the Evap Solenoid ? It should not be hissing either.

https://www.rockauto.com/en/catalog...on,vapor+canister+purge+valve+/+solenoid,4936

 

[91fox]

Yes, the line going from the intake to the vacuum canister purge valve/solenoid, that hose is making a loud hiss, even though I just replaced it with a brand new hose from AutoZone. So, I'm not sure what exactly is going on

 

[91fox]

Does anyone else hear a hiss coming from the purge solenoid with the engine running? I'd like to confirm if that is just a side effect of the part functioning or if it indeed is malfunctioning. Thanks again in advance everyone!

 

[Hamfisted]

Generally speaking, any "hissing" is a vacuum leak. I can't say that I've ever heard hissing from any of my vehicles purge valves. That vacuum line that comes off the intake manifold is also notorious for deteriorating and rubbing off on your hands. They're still available from Ford and Dorman.

 

[91fox]

Update: after clearing the codes, codes p2197 and p0174 came back (both indicating bank 2 lean), I took some pictures of the fuel trim values I'm seeing, I don't know what to make of them, however, they seem to hover in the negative range and very rarely go positive. At this point I'm not sure what the issue may be.. but as always thanks for any positive input I may receive from more experienced individuals!

 

[Hamfisted]

How old are your front oxygen sensors ? Most likely the front bank 2 sensor is bad. If you already smoke checked it and sealed all the vacuum leaks. Compare the output voltages on the forward oxygen sensors. You'll probably see the bank 2 sensor stagnant, as the bank 1 sensor fluctuates up and down as you rev the motor.

 

[91fox]

They both seem to be switching, both sensors are practically new as I replaced the sensors last year and have used the truck extremely little (they were Bosch 15717 I believe) I only replaced the upstreams on both banks. I'll go back out and confirm they're switching.