Exhaust smoke and soot

[Blue)(Fusion]

In October I noticed that after driving at a sustained speed on the highway and then going 3/4 to WOT suddenly to pass someone I get about 3-4 seconds of smoke coming out of the exhaust. I have never seen it before October. Since I can only see it in my rear view mirror and I'm at speed, I can't say for sure what color the smoke is. It does not smoke when starting, at idle, or if I push it hard from a stop or slow speed. It only does it after being at a sustained highway cruise speed for atleast an hour and it will only do it once. It has to go another hour before it will smoke again.

I also have some black soot in the tail pipes which has never happened before. It's not a whole lot, but since I got these pipes installed in June 2009, the pipes have never accumulated any soot in them.

I had to add 3/4 quart of oil 2,000 miles into my 3,000 mile OCI last month. So far on my current OCI I am about 500 miles into it and the oil is still at the max mark where I had filled it to.

My coolant leaks slowly out of my driver side head gasket externally, into the valley. It does not leak enough to puddle, just keep the area damp when running. My coolant has dropped about 1/2" in the degas tank in the last month, but much of this might also be because of the drop in temperature from 50F to 20F.

I have not seen any oil in the coolant or coolant in the oil. But this is only a visual check. I have not gotten an oil lab test.

I have an exhaust leak in the exhaust flange gasket where the passenger side manifold pipe connects to the H-pipe right under the front passenger floor pan.

I have an occasional slight misfire/hesitation at light load at cruise speed. I cleaned the DPFE sensors and the EGR ports look clean. It does, however, go away when I disconnect the EGR vacuum solenoid electrical connector. I still have it connected.

My long term fuel trims are steady at about +5% and +8% at highway speed and about 40% load. They are a little bit higher recently. Since I changed my intake manifold last summer, the fuel trims have been about +4% to +5%. Before that, they were average at -2% to +2%

I have two new HO2 sensors and 8 new Motorcraft spark plugs waiting to be installed. I am waiting because I was afraid that if I put in the new HO2 sensors and I'm burning oil or coolant they will just get contaminated and ruined right away. Then again, if the soot is indicative of a rich mixture then new HO2s may solve the problem. I changed my plugs last summer with stock heat range, single platinum Motorcrafts. The new ones are one heat range colder, double platinum Motorcrafts.

The most recent change to the engine was in August. I removed my factory Non-Performance Improved cams and put in Performance Improved cams from a 2003 Crown Victoria. They have only a slightly slightly increased lift and duration. Timing marks on the chain were set according to the service manual but the cams were not degreed since the cam sprockets only fit on the keyway one way anyway.

There are no codes stored (OBD-II or Ford-specific).

Anybody have any ideas or input on what to do?

[enslow]

Good to see you here too! Well, you know my answer about the smoke. I don't think your oil burning is all that severe for now, but I understand you don't want to replace O2 sensors until you know what to do about the oil.

1. I think the first thing I'd take care of is the exhaust leak.
2. Because you are getting a misfire at cruise, I'd check your MAF voltage.
3. You can check the function of the O2 sensors with a voltmeter. It should switch from 0.8V to 0.2 volts at least once every 3 seconds.
4. I might hook up a vacuum guage to the EGR vacuum line and see that (a) you have no vacuum at idle and WOT and (b) you have partial vacuum to the EGR at mid throttle.
5. Manually apply vacuum to the EGR while the engine is idling. You should hear the engine speed drop. If not, you are not circulating EGR gases and have a fault in the EGR system.
6. When you fix the coolant leak, pull the valve covers off and change the valve stem seals at the same time. It can be done with the cams in place, and if you've got the skill to change cams, seals should be a cinch! The other thing I'd do at the same time is make sure the tapets are cleaned and moving freely before reinstalling.