8V92TA black smoke, low power, overheating?

[Sean]

Once again I need to call on the collected wisdom of the list.

My 8V92TA (DDEC-II) is acting up again.  I am noticing a increased amount of black smoke under load, especially moving from a dead stop.  Subjectively, I am suffering a loss of power as well, with low acceleration off the line.  And, under load, such as pulling a 6% or so grade, temperatures are skyrocketing, and I am having to stop periodically to let the engine cool down.

Turbo boost pressure and fuel delivery rates seem normal, and the cooling system looks normal (fans spinning, coolant level OK, etc.).  Someone has already suggested dragging brakes, but I have temperature sensors in the wheels and all read normal.

Yesterday I replaced the air filter, on the chance that it was restricted.  No change.  I also have a reader (Silverleaf VMS200) on my DDEC -- there are no codes and no abnormal readings, as far as I can tell.  Fuel filters were just changed, and my primary is a Davco FuelPro 380 so I can see that it is not restricted.

I am looking for suggestions on other things to check before I take it in to the shop for professional diagnosis.

Thanks.

-Sean
http://ourodyssey.blogspot.com

[Hobie]

Any chance your muffler has broken a baffle and is blocking some of the exhaust flow?

[maria-n-skip]

  Sean,

     Couple thoughts:
     Bad fuel? Does occasionally happen. In running diesel engines since 91 I have had one really bad tank and the truck acted like what you describe. (I have had several with water in the  fuel very upsetting for what one pays)
     ULSD I've read all sorts of things being blamed on that so of course I'll add that to the list.
     Injectors gumbed up....(probably not by the way you take care of your rig)

   So maybe some injector cleaner additive then run as much as you can and get new fuel.

    With everything you track (boost,fuel flow temp sensors every where) that just about leaves little to blame it on.

   FWiW
   Skip

[Busted Knuckle]

Hi Sean,
Huh, I ain't sure I believe that I'm giving you advice after all, it seems everytime I read your posts I learn something I did not know! But then again I guess you comprehend a learn more from reading than I do (which is cool * great), where as I learn better (or more) by hands on learning experiences!  Anyway I'm gonna see if some of my experiences I had with the "hot rod Setra's" I had will help ya!
On a DDEC controlled 8V92 there should be a boost pressure sensor, if my memory serves correct looking at the engine on the right side of the blower you should find what looks like a GM MAP sensor (trust me even though it looks like one and even has GM on it, it ain't a plain ol' map sensor! LOL! Don't ask, an I won't tell! LOL).I've seen them mounted on a bracket fastened to the blower, or valve cover, & I've seen 'em just laying in the valley on top of the manifold! It'll have a plug with wires going to it and a vacuum hose. The sensors do go bad, but more than once I've found that replacing a dry rotted or melted hose was all it needed. Before fixing this, my engines had the same symptoms as yours. After fixing this the only thing I couldn't pass was a fuel pump or a set of flashing blue light! By the way a DDD is the only place I've been able to find these for replacements! About $90+/- ! FWIW! HTH!
  BK 

[Sean]

OK, lots of good ideas so far.

I did think about the possibility of bad fuel.  We just put in 260 gallons at a cheap-charlie station, and it was ULSD to boot.  I'm not certain, though, that I can say the problem only started after that fuel went in.  I've been noticing progressively more black smoke over a few weeks now, and we only took on the fuel a few days ago.  However, I won't rule it out (but it will be a while now before we burn through the roughly 200 gallons of that fuel still left in our tank).

My muffler is a spiral-type Cowl, so I don't think is has baffles that can break off in the traditional sense, but I will look into this possibility.  We crush our exhaust pipe fairly regularly, as it is a low point in our low-clearance rear quarter, and I did think to check for this on Friday -- I don't see any obvious restriction.  Getting the muffler out to check, though, will be a professional shop activity anyway -- I can't manhandle the massive Cowl and attached exhaust bits by myself, and the bus should really be on a lift.

As for the TBS (Turbo Boost Sensor), Bryce, I'm looking at the boost numbers coming from the DDEC (we don't have a separate gauge), and they look normal (running from zero to around 21-22psi under load), and I would think a bad or disconnected TBS would show up as extremely low boost readings.  I'll try to check it, but it's very hard to get to on our engine, shoe-horned in, as it is, to the engine compartment.

Thanks, everyone, and keep the suggestions coming!

-Sean
http://ourodyssey.blogspot.com

[Sammy]

Sean,
Might have a bad injector, dumping fuel.
If you have the blower with the bypass valve, check that small rubber hose too. It collapses internally.
The purpose of the blower bypass valve is to allow the compressed air (boost) from the turbo to "bypass" the blower rotors and go directly to the airbox ,when the volume of air coming from the turbo is greater than what the blower can handle.
I have also seen the same problem as BK has already mentioned.
Good luck.
Sammy 

[TomC]

As to the bypass blower, that's more a function of getting more efficiency.  If the valve doesn't open, you'll still get just as much air, but because you're not equalizing the pressure on either side of the blower, you'll still be powering the blower which will take a few horsepower, but shouldn't create smoke.  As you indicated, the turbo is showing 21psi.  I would disconnect the exhaust piped before the muffler and take it for a ride.  It'll be loud and since you won't be able to see the exhaust coming out of the normal pipe, have someone follow you to see if it still smokes.  Usually when an injector goes, you'll get a knocking out of that cylinder.  It is very unlikely that all injectors went at the same time.  Also-boost senser might be it.  Good Luck, TomC

[maria-n-skip]

Sean,

   A thought crossed my mind but I'm not sure how applicable it is to your situation. If the ECU programming on your DD is anything like
what they have done to the PU deisiels. There has been many instances where:
  1.   The feul table has errors in it.
  2.   The current usage parameter sets are wrong.
  3.   The sensor code has a bug and isn't reacting to the sensor correctly.
  4.   The updated program has a bug. A lot of times the manufature will send out updates and when the shop uses the new
        the client never knows.

  I don't know if you have had any programming updates but with your handy reader you should be able to clear everything
   back to factory default.

  Just a thought.

   Skip

[Sean]

OK,

I'm going to do the following, and see where it gets me:

1. Double-check the exhaust for any kind of restriction.  Taking the muffler out will require a shop with a lift, so this will be a down-on-my-knees visual only.

2. Get the inspection cover over the turbo off, and make sure the intake has not come apart.  That requires partial disassembly of my bedroom cabinetry and removal of the carpet, so I'll need to get to a place where I have some time to do it all in one shot -- can't be driving around with that stuff undone.

3. Look at the bypass valve, if I can get to it.  Can someone help me to identify this?  Is it attached to the blower, and what side/end of the engine is it on?

Getting any further into the motor, like taking the turbo off to see the blower, or worse, taking the blower off to see the aftercooler, is a major undertaking.  If that needs to be done, I will likely take it back to Pedco, who did an in-frame on this engine 40,000 miles ago.  (I'll have to sneak up on them, so they don't see me coming.  My engine bay is *really* tight.)

Answering the questions that have come up:  I don't think it's ECU programming, since that has not changed.  Although the folks at Pacific Power did get into it, I declined to pay them the $500 they wanted for the update.

Thanks, everyone.  I'll keep you posted here as to what I find.

-Sean
http://ourodyssey.blogspot.com

[Hobie]

Sean,
I'll put a bottle of Trilogy on an exhaust restriction.    I'm wondering if a plumbers camera could be inserted up the pipe.  Hope it is something easy... like some kid stuffed something up the pipe.  Good Luck.

[maria-n-skip]

  Sean,

    I really do hope it is one of the simpler suggestions.
   Even simpler solution would be best.

   I got to tell you paranoia is sometimes justified.....

" (they) did get into it, I declined to pay them the $500 they wanted for the update"

    1. Get into it at any level is a cause for suspicion.
    2. I don't know of any system that does a backup of current that can be reloaded.

   Skip

    I hope I'm out in my field wrong   (wouldn't be the first or the last)

[bounder39]

Once again I need to call on the collected wisdom of the list.

My 8V92TA (DDEC-II) is acting up again.  I am noticing a increased amount of black smoke under load, especially moving from a dead stop.  Subjectively, I am suffering a loss of power as well, with low acceleration off the line.  And, under load, such as pulling a 6% or so grade, temperatures are skyrocketing, and I am having to stop periodically to let the engine cool down.

Turbo boost pressure and fuel delivery rates seem normal, and the cooling system looks normal (fans spinning, coolant level OK, etc.).  Someone has already suggested dragging brakes, but I have temperature sensors in the wheels and all read normal.

Yesterday I replaced the air filter, on the chance that it was restricted.  No change.  I also have a reader (Silverleaf VMS200) on my DDEC -- there are no codes and no abnormal readings, as far as I can tell.  Fuel filters were just changed, and my primary is a Davco FuelPro 380 so I can see that it is not restricted.

I am looking for suggestions on other things to check before I take it in to the shop for professional diagnosis.

Thanks.

-Sean
http://ourodyssey.blogspot.com

Hello my name is Ric I just joined so I am not sure how to put replies up but it could be your turbo I have a 92 series sitting on my shop floor  with a small piece out of a piston and the piece went through the exhaust and took a good bite out of the exhaust side of the turbo. It still ran after that happened but the engine was lazy and it blew a fair bit of smoke. I am not saying your engine lost a piece of piston but it could be a faulty bearing in the turbo. I could get into other reasons but I don't have time. If you could help me figure out how to post this it would be appreciated as computers are not my thing. Hope I could help. Bye for now.

[DrivingMissLazy]

Ric, welcome to the board and you made your post perfect.
Sounds like you are a DD mechanic. Tell us a little about yourself and what part of the country you are in. Again welcome.
Richard

Once again I need to call on the collected wisdom of the list.

My 8V92TA (DDEC-II) is acting up again.  I am noticing a increased amount of black smoke under load, especially moving from a dead stop.  Subjectively, I am suffering a loss of power as well, with low acceleration off the line.  And, under load, such as pulling a 6% or so grade, temperatures are skyrocketing, and I am having to stop periodically to let the engine cool down.

Turbo boost pressure and fuel delivery rates seem normal, and the cooling system looks normal (fans spinning, coolant level OK, etc.).  Someone has already suggested dragging brakes, but I have temperature sensors in the wheels and all read normal.

Yesterday I replaced the air filter, on the chance that it was restricted.  No change.  I also have a reader (Silverleaf VMS200) on my DDEC -- there are no codes and no abnormal readings, as far as I can tell.  Fuel filters were just changed, and my primary is a Davco FuelPro 380 so I can see that it is not restricted.

I am looking for suggestions on other things to check before I take it in to the shop for professional diagnosis.

Thanks.

-Sean
http://ourodyssey.blogspot.com

Hello my name is Ric I just joined so I am not sure how to put replies up but it could be your turbo I have a 92 series sitting on my shop floor  with a small piece out of a piston and the piece went through the exhaust and took a good bite out of the exhaust side of the turbo. It still ran after that happened but the engine was lazy and it blew a fair bit of smoke. I am not saying your engine lost a piece of piston but it could be a faulty bearing in the turbo. I could get into other reasons but I don't have time. If you could help me figure out how to post this it would be appreciated as computers are not my thing. Hope I could help. Bye for now.

[Hobie]

Ok guys, here is another tidbit that may provide a clue to Sean's mystery. 

I had a catalytic converter on my car break up internally and a large piece rotated and blocked some of the flow.  I didn't notice any drivability issues, smoke, noise, lack of performance (big v8) until the timing cover gasket failed.  I was not happy as the engine had been rebuilt less than 20k miles prior. 

A wise parts store man asked me why I needed the gasket.  I grumbled about a poor rebuild.  But he offered if this was the only problem with the engine, look at the cat.  He was right on the mark.  The resulting back pressure found the weakest place to blow.
(Note to self, always buy the large, quality cat not the 'universal' catalytic converter)

Long story but if Sean's exhaust had been smashed several times, over time, could the resulting back pressure have caused a gasket or something else to weaken producing the symptoms he currently has. 

So my question to the brains here is:  If the exhaust had such a restriction, what would that cause to fail?  Fouled injectors?  Rings?


Another long shot.

[Sean]

Hobie,

That's an interesting theory.

We've crushed the exhaust, to a significant restriction, only twice.

Once was before the in-frame, and it was repaired before the in-frame was finished.

The second time was crossing the Big Puddle (http://ourodyssey.blogspot.com/2007/02/big-puddle.html) earlier this year.  We knew about that right away, and thus drove very gingerly to All Coach to have the exhaust fixed before we put any heavy loads on the engine.  I guess it's possible we did some damage then, but I don't think we've seen symptoms until this past month or so.

Incidentally, I replaced the secondary fuel filter yesterday -- no change.

Does anyone know if a Davco FuelPro 380 can be "plugged" without the bowl filling most of the way?

-Sean
http://ourodyssey.blogspot.com