UPDATE 3/13/10: Shepherd Engine Saga - Epilogue

[JackConrad]

Jim,
Glad to hear you got it fixed.  I think I will just stay with my MUI engine.  Jack

[bobofthenorth]

Update 2/28/10  OK folks, I just took the bus on another drive and it seems that all is well.  Pat did not go with me,  ...............   

Well - - there's the problem right there.  Its a well known fact that wimmen shouldn't be around any machinery more complicated than a sewing machine or a vacuum cleaner.

Glad to hear you got to the bottom of it Jim.

[RTS/Daytona]

Hmmmmm - what did I tell ya !!!!!

[luvrbus]

Lesson learned here a DDEC will control the boost pressure and a bad wiring harness will make a Eaton flash

good luck

[rv_safetyman]

Lesson learned here a DDEC will control the boost pressure and a bad wiring harness will make a Eaton flash

. 

You forgot the part about lost hair

I can tell you for sure that if I had had hair before this whole episode, I would have lost it.

As I said in a previous post, in some perverse way, this whole trouble shooting process was somewhat "enjoyable" to this crazy engineer.  It is terrible to be a bus nut and a crazy engineer all in one package.

Thanks again so much for all the great input.  I know I learned a ton from you folks.  I sort of know my DDEC a bit better than I did a few months ago

Jim

[Van]

Great news Jim , now what you need is a refreshing drive, like down to the rally in Texas . felt so bad for you as you did for me, now every body is happy. Whew! I think I need a trip to Disney or something like that . Didn't someone say we'd have a good laugh when this was all over , I think I'll have a good cry first Good work Jim as always

    Van

[Busted Knuckle]

Great news Jim , now what you need is a refreshing drive, like down to the rally in Texas . felt so bad for you as you did for me, now every body is happy. Whew! I think I need a trip to Disney or something like that . Didn't someone say we'd have a good laugh when this was all over , I think I'll have a good cry first Good work Jim as always
    Van

Just drive on over to Franklin, TX you'll think you have been to Disney! (after meeting Goofy, Pluto, Mickey and the other busnuts that'll be there!
   BK 

[Dreamscape]

Good News Jim! Now go for a long drive and enjoy the fruits of your labor!

I'm Sneezy by the way!

[DaveG]

Wow Jim, what a good feeling to have that over with! What a pain, but what a sucess! Congratulations.

[kyle4501]

Well, so much for the theory that the electronics will tell you what is wrong or "where it hurts". 

There is no substitute for understanding the whole system & old fashioned troubleshooting. 
Even better when you have friends that will help troubleshoot.
As good as the electronic stuff is, there is something to be said for using old fashioned mechanical gauges to verify the electronic.


Now, does this mean you won't need heat in your shop? Since you'll be driving instead of working on it . . .   

[belfert]

It is kinda hard for the ECM to know that a different sensor is being used than the one the ECM is programmed to work with.  If the sensor was faulty the ECM would probably know that and report it.

Electronics are both a blessing and a curse.  Electronics can make for far cleaner emissions and somewhat better fuel economy, but mechanics use them as a crutch instead of doing real troubleshooting.  The first thing any mechanic will do these days is hook up their scanner.  A lazy mechanic won't investigate further if the scanner shows no faults.

[kyle4501]

That was my point, electronics are only a part of the system - NOT the absolute answer. Seems most people think the scanner does all the troubleshooting work & tells exactly what needs to be replaced - that ain't so.

There are fewer & fewer mechanics out there today - they have been replaced by scanner readers who think replacing the sensor that flashed the code will solve the problem. 


When you consider the reliability of the newer stuff combined with the disposeable goods mentality, then add in the wal-mart pricing minded customers complaining about how much the mechanic charges . . . .

Doesn't seem to be much demand for really good & experienced mechanics.   

[rv_safetyman]

I am not sure it is fair to lay all of the blame on electronics here.  Recall that I was doing a "mix and match" here.  I put my original DDEC IV ECM (albeit programmed to operate on a DDEC III engine) on the replacement DDEC IV engine.  So, I really am to blame for the problem.

The reading I had done suggested that ECMs of the same vintage are interchangeable.  Obviously not true.  In hind sight, my move was ill-advised.  However, my thought process seemed reasonable at the time.  

Recall that the AutoShift has to talk to the engine.  I did not want issues in that area, and chose to use the original ECM since I knew it talked to the transmission very well.  As I said, I did not find any information suggesting that would cause a problem.

I am really glad that the process went the way it did.  My next move was to put the replacement ECM back on the engine.  If I had done that without learning about the difference in boost sensors, I would have missed an important piece of information.  Replacing the ECM would have cured the problem, but I would not have know why.

Putting the replacement ECM in the bus is not just a drop in.  It must be programmed for the specifics of the bus.  The tire size and rear end ratio must be reprogrammed.  In addition, some transmission information must be re-programmed.  That can be done with a ProLink.  I changed the tire size and rear end ratio, but there is some transmission calibration that is not correct, as I am not getting speed and have a fault code showing for that problem.  I will need to figure that out, but should not be a big deal.  I knew going into the conversion of ECMs that the replacement unit was programmed by DD for J1939 communication.  That gave me some confidence that it would talk to the AutoShift and it did.  If the J1939 had not been activated, I would have had to have that done by a dealer, as only the "factory" can do that .

So, the electronics did their job, and none of the sensors had failed.  There was not a condition that justified a fault code.  In the real world (not the crazy mixed up "world of Shepherd") this would not have happened.

Having said all of that, I still have not gotten my "see I told you so" call from Sonnie

Jim

[kyle4501]

. . . .
So, the electronics did their job, and none of the sensors had failed. There was not a condition that justified a fault code.  In the real world (not the crazy mixed up "world of Shepherd") this would not have happened.
. . . .Jim

I'm not so sure about that . . .
Many times I have received the wrong part - looked right, but wasn't. I've even had to pay for unnecessary repairs because the first part didn't fix it - $$$ later, the first part gets replaced again & the problem was solved.
My point was & is that there is no substitute for understanding the whole system. One can not simply rely on one tool to fix everything. One cannot trust all parts in the system to be correct - but that is where we must start & where total understanding of the whole system comes in handy. 

Jim, you are to be commended for posting this opportunity for us all to learn from. Your tackling of the electronics is not for the feint of heart.

[bevans6]

"My point was & is that there is no substitute for understanding the whole system. One can not simply rely on one tool to fix everything. One cannot trust all parts in the system to be correct - but that is where we must start & where total understanding of the whole system comes in handy.  Wink  "

Words to live by, my friend!

Brian