A while ago i noticed when changing the old spark plugs #5 was had carbon on it...i went with the recommended ford plugs/wires....fast forward i noticed i am burning just over 12oz of oil 200 miles...10/30 ..does not smoke on start up/no leaks. When i bought the truck and could see it had new heads..engine runs perfect ..i pulled #5 new spark plug and it was sooty and could see on the tip of the threads carbon, all other plugs burning clean.... smooth idle...should i worry about this or could it be the intake gasket cracked sucking oil into the #5 intake...but would the engine run rough at idle if the gasket was the problem.......or should i forget about it....144,500 miles
I took this picture off the internet showing the intake gasket

 

It wouldn't be a cracked upper intake manifold gasket, if it was there would be a vacuum leak and it would run like crap.
I'm thinking that who ever rebuilt the heads forgot to put the valve seal(s) in or they came loose.

 

Today I pulled the plastic intake and tightened the intake bolts..got 1/4 turn...but like you say valve seals..or rings...Can not spray it with carb cleaner because the valve cover covers the top of the gasket..Overnight cool down, no smoke at first start up...Just want to add if the intake gasket had small crack upper or lower would it run bad, the crankcase is sealed...at idle pulling the oil cap..slight stumble then smooths out...no history on this engine..
I will leave it as I don't use truck every day.

 

If you took the plastic intake manifold off, then you could have gone a little further and removed the valve covers.
You could have taken a pen flash light and shone it in between the valve springs to see if the seals were there and/or in place.

 

Thanks Jeff...pulling the plastic manifold is quick....maybe in the future i will get into it..i know if i check the valve seals and they are ok...i would dive into it and pull the intake..not a daily driver...

 

I would do this test.
Start engine and then pull out the Fuel Pump Relay or Fuel Pump fuse in the engine fuse box while engine is running.
Engine will stall and fuel pressure will be 0psi

Leaving relay or fuse out, crank the engine a few times and then pull out #5 spark plug, should have oil residue if valve guide seal is leaking bad enough to use 12oz in 200miles

If you wanted to go further then next step would be a compression test
If #5 was lower than the others then yes ring issue in #5.

I assume there is no visible oil on the under side of the engine or transmission so you believe only way out for the oil is being burned in #5

12oz of oil is quite a bit in 200miles, I would expect #5 to be misfiring fairly fast if that much oil is leaking in.

Whats your MPG like?
Leaking fuel injector can cause the sooty black as well

 

Thanks Ron.....i replaced the injector a few weeks ago, no change...went out with truck before i read your info...normal lazy ,driving 65mph i get about 20 mpg...but today i decided to give it a good belt on the freeway no O/D 3,500+RPM for five miles, it did ping when hammering it ..No misfire in the engine/no leaks...thing is there is no blue smoke at cold/hot start ups..Picture of #5 spark plug after run, lot cleaner than before...when i got the truck it had autolite 404 plugs they were all tan color #5 was full of carbon...new motorcraft plugs look like the picture but not black..I will have to do some normal driving and see how the plug looks, i was hoping tightening the manifold would fix it. will try what you said later..

Just wanted to update to confirm exactly 200 miles 16 Oz of oil..wow I got something going on here lol

 

Did the crank test no oil on spark plug, so it looks like the piston rings, using Marval mystery oil topping off (hoping it will clean the rings)
Using truck as daily driver now our car was in a wreck Nov 6th totaled ...Ranger running perfect until i got check engine light PO175....Bank 2 rich...cleaned MAP sensor, clear codes, then after 75 miles i got a PO172, bank 1 rich i had a gut feeling it was the plastic intake gaskets as i did not replace them when i changed the injector #5...so changed the 0 ring gaskets manifold....ran perfect almost 100 miles freeway/ town driving then PO172 came back.....so i got a lean condition some where no vac leaks i already replaced the upstream 02s but not the rear, so i replaced that yesterday...waiting for next run out, trying to fix this without buying a scan tool fuel trim

 

Update...Cold engine i drove to the post office no more than two minutes one way, turned engine off for one minute. Restarted on the way back the check engine light PO172 back on again....but wait the engine is still in open loop?? not at normal temp yet... i have a good used MAF sensor so i fitted that, run out again ok... i will do the same run in the morning..

 

Closed loop is time based not strictly temp based.
Generally the Ford computers switch to Closed Loop after 180 seconds(3 min), RPMs above 400 start that timer.

Closed Loop means computer will use O2 sensors to "trim" air:fuel mix
An O2 sensors needs to be 600degF or hotter to work well
So after 180 seconds computer tests O2 sensor voltage, if it is changing voltage quickly then it is hot enough to be used for emissions control, which is also the point of O2 sensors, lowering emissions.

Air temp and coolant temp are also used, but to modify air:fuel "trim" for weather and engine conditions, so computer can be in Closed Loop and still be in "choke mode", i.e. running engine richer, with more spark advance and higher idle.

And if engine is already partially warmed up, i.e. coolant temp sensor above 100degF, then Closed loop will start almost immediately on restart, computer will watch O2 sensors for the fast changing voltage within a few seconds of restart, and once they are "deemed" reliable Closed Loop starts

In 1998 Ford modified head designs and exhaust manifolds to get instant heat out of heads to warm up O2 sensors faster, required by newer emissions maximums for cold starts.
So Closed loop happens pretty fast on the newer the vehicles.

P0172, Rich on Bank 1(passenger side) means the computer is lowering the Open Time for the fuel injectors on that bank because there is not enough Oxygen in the exhaust by what O2 sensor on that bank is reading.

O2 sensors can only "read" Oxygen levels not hydro-carbons, i.e. gasoline or oil "fumes"
If too much Oxygen is consumed when cylinder fires then there was too much fuel added and so less Oxygen for O2 to "read" in exhaust, Rich condition.

If too much Oxygen is in the exhaust then not enough was consumed when cylinder fired so not enough fuel was added, Lean condition, mis-fires consume no Oxygen, so show as Lean

So on your return trip Closed loop would have happened soon after restart.

Downstream O2 tests if Cat Converter is working, so not part of fuel trims but does play a small part in long term fuel trims(LTFT) .
Long trim fuel trims can not be cleared from computer, well I think Ford makes a OBD reader that can do it but not available to general public.
Any way the point of LTFT is moot if you clear it, lol.
Over time engine conditions change, compression is lower, fuel pressure is lower, small vacuum leaks occur, ect.........normal wear and tear.
LTFT is used to bias computer to engine/vehicle condition as it ages

Vacuum leaks and MAF sensor issues are almost always Lean codes, because unreported air is coming into engine, so computer is not adding enough fuel, and you get a Lean burn, too much Oxygen in the exhaust.

Rich code could be a MAF but they don't tend to over-report air flow.

Now it could be LTFT has been in the minus numbers for awhile and changing O2 sensor will bring it back closer to 0, and that just takes time, a few weeks sometimes.

Short term fuel trim(STFT) is the computers instant reaction to O2 sensor readings
Generally these are -8 to +8
- means less fuel being added, + means more fuel being added
0 is the computers calculation of 14.7:1 air:fuel ratio based on RPM, throttle position and MAF data
When STFT is -15 or +15 for any length of time computer will set Rich or Lean code
OR
If STFT and LTFT combined is -15 or +15 it will also set Rich or Lean code

So if LTFT is -8 and STFT is -7 you could get a Rich code

If possible get OBD reader for the LTFT, and then STFT at 1,000 RPMs, and 2,500 RPMs
Then after driving for a day, longer than 15 minute drives
Check LTFT again and see if it is changing, lower - number

 

Thanks Ron good info.....well i did my same run after fitting good used MAF....no check engine light coming back home.... took ranger thirty mile run all ok, hope this is the last of it..

 

Strange thing i still get the check engine light PO172 but it only comes on when i drive to town slow during warm up 20 to 30 mph. If i start up cold and idle five minutes and hit the freeway its ok..

 

Engine under load warms up faster, hotter exhaust, so quicker O2 sensor and less time to burn off any oil in a cylinder, if that's the problem.
Idling is slower exhaust warmup, so oil can be burned off before O2 and closed loop

But just a guess

 

Running from cold (no blue smoke from exhaust) in my garage idle/ few minutes then taking it to 2,000 rpm, then back to idle check engine light again..Thinking it was the 0 ring on the MAF i replaced it....did same thing but engine normal temp so no light...
I did read when removing the MAF for cleaning you should remove neg terminal from battery five minutes ...the ECU fuel trim re learning...fingers crossed lol

12/17 Just done 150 miles since yesterday afternoon ..no check engine light