On 250-500 mile trips, I am experiencing considerable soot in my tailpipe on my 96 5.0 V-8. A few weeks later, it clears up. This time during a long 500 mile trip, I got a check engine light that came on and then went off after a couple of days. The truck has about 96K on it. Has original plugs and wires and does not use any oil.

Some have suggested changing upstream O2 sensors. Any other thoughts? Thanks Mike

What code the CEL produce?

Well, close to 100k miles you should definately change your plugs and wires and do a full service. Basically fluids, cleaning, and plugs/wires.

Did you see if there was a code, or did the light go out before you checked it? Sounds like you're running rich on the highway, which could be due to any number of issues.

Alex and Al: Fluids have all been changed..gone to Mobil 1 tranny fluid also. Will have Ford tech. pull CEL codes this week plus put in new Motorcraft wires, plugs plus O2 senors if it needs it. Mike

Dird it use any oil on the trip?

Not a drop. Level was/is right exactly where it was 2000 miles ago. Mike

Sooty exhaust cured! Had my 5.0 tuned up with new Motorcraft wires, plugs, filters, ect..also had two new upstream O2 sensors installed. Just returned from a 600 mile pull with my travel trailer and the exhaust is clean. No soot now! Mike