Truck has rough idle. Puffs white smoke at idle. Help?

[Afboy143]

Hey guys,
I haven't posted here in years. A few years back I gave my explorer to my sister and bought a Mustang and started to really be on those forums.

My sister brought my old 1999 Ford Explorer Sport 4.0L SOHC to me saying it's giving her really bad gas mileage. The truck has 170K miles on it.

It had codes so I pulled them, P0171 and P0174. While poking around the engine I found the PCV valve was out of the tube it sits in. I also found the T connector that connects the PCV valve to the hoses going into the upper intake was cracked. I replaced the PCV valve and used a generic T connection utilizing a universal T connector and fuel line. I put a clamp around the hose for the PCV valve so it doesn't come back out.

I cleaned the MAF as it was really dirty.

I also replaced the thermostat in the housing as it was leaking so I figured if I'm replacing the gasket, why not the thermostat as well.

Fuel filter was replaced with a Drive Works generic filter from Advance Auto.

Upon removing the throttle body to clean it, I found wet liquid behind it and the build up of carbon was unreal. I thought this might be to the PCV valve falling out of the tube and not doing it's job for God knows how long.

My question is after doing all the above, the truck smokes pretty bad at idle (which it didn't do before). It's a white smoke. Also, you can smell a strong smell of burnt carbon upon heavy acceleration. Is this because the PCV valve is actually doing it's job and there is so much crud in there?

The truck also starts up rough and idles rough for a minute after sitting for hours, but if you drive it and let it sit for minutes, it starts right up without hassle.

I have no idea what to do, and the codes mentioned above are still present. Any ideas?

 

[jremington59]

Could be your intake gaskets. I'd probably start by cleaning the MAF and see if that helps.

 

[Afboy143]

Could be your intake gaskets. I'd probably start by cleaning the MAF and see if that helps.

I do appreciate the input. After looking at past records, the upper and lower intake gaskets were replaced at around 132K.

The MAF has already been cleaned as mentioned above.

Would a faulty MAF cause the smoke and smell as I described?

 

[Afboy143]

I'm thinking the white smoke and oil in the upper intake manifold could be due to the PCV valve not in the crank case tube it's supposed to sit in for long amounts of time and its burning all the crud off now. Does this sound accurate?

 

[Afboy143]

I was just told that since the PCV valve was disconnected (for who knows how long) that it can cause the blow by that the PCV would usually extract to backflow into the upper intake hence why oil was found in there. Thoughts?

I'm wondering if the smoke and smell is just the built up crap burning off now that the PCV valve is connected.

 

[my98nnj]

The PCV system is supposed to extract gasses from the crank case and redirect them back into the intake to be burnt through the engine. If it wasn't working, there wouldn't be any build up in the intake. The engine would have been blowing the bypass out the PVC system into the air.
With that said, with the system working you're now pulling the blow by into the intake and burning it off. If by chance the engine has bad rings, which would explain the poor MPG then you're also getting excessive blow by being sent into the intake and being burnt off (smoke). I think a compression check is in order.

 

[Afboy143]

The PCV system is supposed to extract gasses from the crank case and redirect them back into the intake to be burnt through the engine. If it wasn't working, there wouldn't be any build up in the intake. The engine would have been blowing the bypass out the PVC system into the air.
With that said, with the system working you're now pulling the blow by into the intake and burning it off. If by chance the engine has bad rings, which would explain the poor MPG then you're also getting excessive blow by being sent into the intake and being burnt off (smoke). I think a compression check is in order.

This makes perfect sense. I appreciate the input. I was actually told the rings thing as well and your explanation makes perfect sense.

Now that the PCV valve is working correctly, that sounds right like you have said. Instead of everything blowing off into the atmosphere, it's being recirculated now. Sounds like to test this theory aside from a compression test, I can disconnect the pcv valve and see if the white smoke is still there, correct?

 

[jremington59]

Here's some things to look at. Also, did you replace the PCV? If it were out for an extended period it could be seized. After reinserting the PCV did you reset the codes and see if they came back?

A code P0171 may mean that one or more of the following has happened:
•The MAF (Mass Air Flow) Sensor is dirty or faulty
Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
•There could be a vacuum leak downstream of the MAF sensor
•Possible cracked vacuum or PCV line/connection
•Faulty or stuck open PCV valve
•Failed or faulty oxygen sensor (bank 1, sensor 1)
•Sticking/plugged or failed fuel injector
•Low fuel pressure (possible plugged/dirty fuel filter!)
•Exhaust leak between engine and first oxygen sensor

 

[Afboy143]

Here's some things to look at. Also, did you replace the PCV? If it were out for an extended period it could be seized. After reinserting the PCV did you reset the codes and see if they came back?

A code P0171 may mean that one or more of the following has happened:
•The MAF (Mass Air Flow) Sensor is dirty or faulty
Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
•There could be a vacuum leak downstream of the MAF sensor
•Possible cracked vacuum or PCV line/connection
•Faulty or stuck open PCV valve
•Failed or faulty oxygen sensor (bank 1, sensor 1)
•Sticking/plugged or failed fuel injector
•Low fuel pressure (possible plugged/dirty fuel filter!)
•Exhaust leak between engine and first oxygen sensor

I appreciate the post!

-Yes PCV was replaced and the only one was gummed up. I replaced the T fitting as well on the PCV as it was cracked. Yes, after replacing the PCV, the codes came back.
-I checked all vacuum lines and saw no cracks.
-MAF was cleaned; however, it wasn't tested for proper operation. I'll do that tonight. I'm not running an oiled filter. It's an AMSoil dry flow filter.
-Didn't check the bank 1, sensor 1 O2
-Fuel injectors have been replaced with cleaned and reflowed approx 50k miles ago.
-Changed fuel filter. Didn't test fuel pressure.
-No exhaust leak

My main concern is the white smoke all the sudden - that doesn't smell sweet. I'm leaning very much so toward rings on the pistons as I didn't see this smoke prior to the PCV valve being reinstalled.

 

[my98nnj]

Did you by any chance check the oil level?

 

[Afboy143]

I did not; however, I did check the gas cap for a white foam (indicator of a blown head gasket) and I saw none which was good.

I'll post numbers on the compression once I get them.

 

[jremington59]

Did the vehicle sit for a long time? And did you replace the grommet for the PCV?

Wouldn't hurt to spray a little starter fluid around the intake and lines and see if there's any change in RPM's. Do it when the engines cold.