Let's play a guessing game

[Alphamonk]

We just took our first trip in our 05 Signature. Not a good one. Less than two hours into the trip, we developed major problems. I have the Detroit Diesel engine. I will describe the systems and you guys guess thecause . Should be very informative for you Detroit owners. The engine started bucking and backfiring and belching black smoke. Because this unit set for three years, my first thought was fuel filters. Nope. Six hours later we figured it out. I want you guys to take a shot at it. Then I will reveal the culprit.

[Old-Biscuit]

Black smoke......incorrect fuel/air ratio......fuel rich

Air cleaner or obstruction in induction

[Stretch]

Since these engines are near bullet proof, I know it's not major components. So I'll guess turbocharger related. Or crack in charge air cooler. Maybe?

[Alphamonk]

Well so far it looks like the EGR valve. Had two different people tell me it was probably the turbo,(without even looking at it). Then I talked to a lady at another shop and she said unplug the EGR valve and see if it stops. It did. Now I am just suffering from a lack of power and a little black smoke when I take off. NowIhave to try to find one. It only has 28,000 miles so you wouldn't think it should anything serious.

[CampingCajun]

It may just need to be cleaned instead of replacing it.

[Alphamonk]

Someone suggested cleaning it but I was not sure that was possible. Can you clean these things on the Detroit Diesels?