My wife has an '03 6.0 Excursion that she uses to pull a horse trailer. We've owned the truck since new, and it has been well maintained. It has 130K miles on it. The last major maintenance was the replacement of the EGR Cooler a couple of thousand miles back. No tuners have been installed on the truck.

A couple of weeks ago while on a 2 hour road trip she called me to report that the truck was losing power when climbing hills, but ran fine on the flats. On her way home a friend followed her and reported occasional instances of dark, black smoke coming from the exhaust.

Based upon the lost power under load situation, my first thought was that the fuel filters needed replacing, but I could not relate the black smoke to that symptom (since black smoke usually means too rich, and a clogged filter means too lean). Nonetheless, I checked (and changed) the fuel filters - the old ones looked great but I replaced them as a precaution. I also checked (and replaced) the air filter. The indicator did not reveal a problem and the old filter was not too dirty, but just to be safe replaced it.

The problem still exists, and there seems to be a cylinder "miss" at low speeds. At some times the engine is clearly "flooded" with diesel, based upon the black smoke and lack of power.

There are no codes showing. I'm presuming that the problem is probably a bad injector, but am not sure. Can anyone advise how I should go about troubleshooting further, or if there are any threads here on FTE that I should read?

Thanks in advance for the assistance.

 

Cylinder contribution test... can you run that?

 

the egr valve could be sticking or stuck part way open do to a piece of carbon. on the 03 it doesn't monitor the egr as close as on the late models so it may not turn on the CEL. I would think that if were an injector it would do it all the time.

 

If the low speed miss is consistan then I would bet that you have an injector going bad.

When was the last time the oil and filter were changed, and are you using oem filters only?

You can run a cylinder contribution test with the Auto Ingenuity software I believe, other than that it will need to go to the dealer to let you know what, if any, injector(s) need replacement.

I would check it for codes first and see if there is anything present.

Sarge

 

lots of threads here about 03 trucks and icp sensors there first.

 

What code reader are you using? Not all are created equal and you may indeed still have codes that it isn't picking up.

If you have something like AE, I would do a cylinder contribution test and see if there are any problems with the injector(s) that way.

EGR valve could cause loss of power and lots of black smoke that's for sure. That could be another possible place to look

I think ICP sensors were an issue with the 03s, but I could be wrong with that.

 

All - thanks for the feedback. We used two different code readers - a Snap-On one from a professional garage and a Diablo (part of a tuner). Nothing showed up on either.

Oil and filters have been changed on 3 - 4K intervals since new (I know that it's overkill, but my desire was to get 300K or more miles out of this truck), with Motorcraft filters all along.

I'm not familiar with the cylinder contribution test; I'll check into having one performed along with testing the ICP sensor.

Thanks again - please keep the feedback coming.

 

Basically what the cylinder contribution test is to selectively turn off one cylinder at a time, and see how much the RPM drops.

That tells you if one is "weak" at least at idle.


A lot of times, it takes a while to get codes to "show".


I had a turbo hose blow off last week... and after I did the repair, the Turbo underboost code came up!!!!!


Needless to say, the code got sent home real fast (erased).

 

Well with codes you also have to realize that sometimes it takes a certain amount of drive cycles, frequency, and/or severity of the issue to trigger a code.

OP: You might want to try looking at the Freeze Frame Data, that might have some helpful info to diagnose with.

 

UPDATE.

A friend is bringing over an analyzer today, and we will run the cylinder contribution test as well as test the ICP sensor.

Funny thing though... last night when I started the truck up to move it into the barn, there was no smoke and no misses. It was as if the problem was nonexistent. The last time that the truck was started (last weekend), the miss was very evident.

I did notice that the power appeared down, as when the miss was not evident I powerbraked the truck to see if it showed up under load. The power felt weak - would not break the back tires loose or even come close. This makes me wonder if - in addition to whatever caused the smoke and the miss - the turbo vanes are potentially frozen (happened once before and was cleaned under warranty).

 

Wire and harness chaffing is common on the early model year engines .....

 

sorry to hijack this thread but i was just wondering how you do a cylinder contribution test i cant figure it out on my AE thanks

 

If I recall correctly it's in the actuation menu. You'll need the 8.2 software, if you don't have that go to AE's website to download the latest one.

 

Update: The cylinder contribution test came out fine, and the miss has not reappeared. However, just to be safe we removed the turbo and the EGR valve, and I cleaned both.

The EGR was not bad at all; the turbo however exhibited some signs of rust between the vane adjustment plate and the center housing.

After a thorough cleaning, everything is reassembled and running well.

The cause of the original cylinder miss is still perplexing though; other than changing the fuel and air filters and adding a high concentration of fuel cleaner to the tank, nothing else was done that could have impacted fuel delivery. The truck did sit for a couple of weeks after adding the injector cleaner; so one possibility is that an injector might have had some gunk in it that the cleaner dissolved.

Thanks again to all for their suggestions and advice.

 

Update: The truck has been running smoothly, but is still losing power under load (and the situation is getting worse). Today my wife couldn't make it over 50 mph pulling the horse trailer back from an event. We don't drive the truck very often (stays hooked up to the trailer), maybe once a month or so.

The black smoke and miss problems have not reoccured since the turbo was cleaned.

When the power drops, the truck does not seem to surge much, it's as if a governor kicked in. I'm wondering if the root cause is a fuel pump, but am wondering if the ICP sensor could cause this problem.

Still no codes being thrown either.

Any advice?

Thanks much.

Scott