Tube Name Question

[99fordexplorersohc]

Hi everyone,

I have been dealing with a check engine light pushing P0171 and P0174 codes. I ended up replacing the PCV valve and the EGR valve but haven't been able to resolve it. I made a homemade smoke machine and put it through my engine and discovered smoke coming out of the locations circled in the picture below. I think I may need to replace the tubes but I am not sure what they are called. Do y'all have any suggestions?

 

[XLTrunner]

How long has it been since the upper and lower intake manifold gaskets were changed? Very common source of vacuum leaks on these engines that trigger the lean codes.

The plastic one is the IAC inlet tube. Not sure what the other one is called.

 

[donalds]

The other one is the Pcv inlet

Intake gaskets ∆∆∆∆∆∆∆∆∆

 

[C420sailor]

The plastic one feeds the IAC with filtered air, I believe.

I would be surprised if the hoses were the source of the leak. You need a pretty good sized leak to trigger an 0171/0174.

 

[99fordexplorersohc]

How long has it been since the upper and lower intake manifold gaskets were changed? Very common source of vacuum leaks on these engines that trigger the lean codes.

The plastic one is the IAC inlet tube. Not sure what the other one is called.

As far as I know, they have never been changed. I bought some new gaskets but ran the smoke machine before replacing them to avoid the work and that's when I noticed the smoke coming out of the EGR valve and those hose locations. I didn't notice any smoke coming from the manifold itself so I assumed that the gaskets were fine. Is this a proper conclusion to make? Perhaps I wouldn't see smoke coming from the manifold yet they could still be the problem?

 

[CDW6212R]

How much is leaking from those locations is a big question. If there is a lot from some leaks, other leaks will not be visible until you fix the larger leaks.

That large hose going to the valve cover may be too large of a size, and it might leak a lot at the ends. If they fit somewhat snugly, I would seal the ends with a light layer of Ultra Black on the inside of each end.

Check the PCV and hoses too, they are at the back and heat can make them become a looser fit.

 

[DR98FL]

I agree about the hose to the valve cover is too big, compared too my old ford piece.

Is there a online source for this hose? Also a part #. I went to the dealer years ago and got my current replacement.

 

[99fordexplorersohc]

How much is leaking from those locations is a big question. If there is a lot from some leaks, other leaks will not be visible until you fix the larger leaks.

That large hose going to the valve cover may be too large of a size, and it might leak a lot at the ends. If they fit somewhat snugly, I would seal the ends with a light layer of Ultra Black on the inside of each end.

Check the PCV and hoses too, they are at the back and heat can make them become a looser fit.

View attachment 342056

I'll try the Ultra Black today after work, thanks for the tip! I replaced the PCV valve about a week ago so that shouldn't be an issue. I'll see how it runs after putting that sealant on. I guess if the CEL still stays then I'll end up replacing the gaskets.

 

[CDW6212R]

My original hose there at the VC was loose when I serviced the engine at 77,450 miles, and later I decided I didn't like it coming off so easily. I made it stay with the RTV even though I didn't have a CEL at the time. All of the rubber hoses and grommets that are close on the engine will shrink from the heat. The 302 is bad about that with the PCV grommet in the intake manifold, the PCV will get blown out easily from any internal pressure(old age, mileage) there.

 

[99fordexplorersohc]

My original hose there at the VC was loose when I serviced the engine at 77,450 miles, and later I decided I didn't like it coming off so easily. I made it stay with the RTV even though I didn't have a CEL at the time. All of the rubber hoses and grommets that are close on the engine will shrink from the heat. The 302 is bad about that with the PCV grommet in the intake manifold, the PCV will get blown out easily from any internal pressure(old age, mileage) there.

Ah thanks for the heads up. I put the RTV on the hoses I pointed out in my first post so I'm praying that it helps. I'll give an update once it cures and I've driven it for a bit. If I end up having to replace the gaskets I'll be sure to check out the grommet as well.

 

[CDW6212R]

Your V6 PCV is an odd assembly of the hoses at the back, and the PCV at the center connection. I think that was only available from Ford as an expensive assembly.

 

[BKennedy]

Aren't those hoses only to vent oil vapor back into the intake instead of the atmosphere? I don't see how them leaking would effect anything. I am guessing that they leaked with the engine not running. If the engine is running, it will suck the oil vapor into the intake and burn it off, correct? No need to replace those hoses unless they are split.

 

[C420sailor]

Your SOHC doesn’t have a PCV grommet, but it’s a great time to replace PCV valve and hoses.

Also the green EGR to manifold o-ring.

And your front cam chain tensioner.

And your thermostat housing (if original), thermostat, and sensor o-rings (if clip-in type).

As you can see, pulling the manifold is a great opportunity to catch up on some PM.

 

[CDW6212R]

Aren't those hoses only to vent oil vapor back into the intake instead of the atmosphere? I don't see how them leaking would effect anything. I am guessing that they leaked with the engine not running. If the engine is running, it will suck the oil vapor into the intake and burn it off, correct? No need to replace those hoses unless they are split.

Yes it is very minor, the PCV system is a controlled vacuum leak into the engine, into the inlet hose etc. The PCV itself is the limiting restriction, if those hoses leaked outside air in, it shouldn't throw a code because it still has to go through the PCV. But it would be unmeasured air instead of coming from the MAF, a small leak like that shouldn't be very important.

 

[99fordexplorersohc]

Just an update, that Ultra Black did not help things so I am going to tackle replacing the intake gaskets today. It seems that the vacuum leak is getting a bit worse, my car stalled at an intersection yesterday and lately the idle rpm has been hunting and getting to what seems to be 300 and then revving back up. Will give update once this job is done, praying that this is what is going on.

 

[XLTrunner]

Can't say I'm surprised that didn't work. But, was worth a shot before tackling the intake gaskets. Good idea to replace that large "O" ring on the EGR tube that extends into the upper intake plenum while you're at it. This job isn't that bad. I've had mine off several times and have it down to about 20-25 mins to get both intakes off.

 

[99fordexplorersohc]

Hi all,

I replaced the upper and lower gaskets but still am getting the P0171 and P0174 codes. I am honestly at a loss as to what to do right now. My car still idles low and feels a bit rough. I took a video of the code reader data but have no idea how to read it. I rev up the engine about half way through to check changes. If someone could give guidance as to what to do now, I would super grateful! Here is the link to the video:

 

[CDW6212R]

Have you checked the fuel pressure yet? It needs to be above about 55psi, less will begin to create the lean codes.

How about cleaning under the hood, and looking for other items out of place or leaking etc. That engine looked like it hasn't had much attention for many years.