Augh - I should offer a prize for this correct diagnosis!!

[KandT]

Here is the bullet pointed story.  God bless anyone who can figure this one out!

Part One
1) Rig runs perfectly for 4 hours home from last trip (had been running great).
2) Rig sits for a month or so and we head out on our next trip.  About a half mile in the "Check engine Light and Stop Engine" light come on
3) We keep rolling despite poor engine performance and the buzzer and lights intermittently going off.  Uphill causes the lights to come on and buzzer to sound.
4) DW who has been googling the whole time says someone says it might be a loose battery connect (Diesel engine but what do I know about the newish diesels)
5) I had only hand tightened the batts so I grab wrench and torque them down.
6) Problem goes away for a WEEK and OVER a THOUSAND HARD HILLY BUMPY MILES TOWING AN ACCORD!!!  Methink problem solved and that we are brilliant! 
Part Two
7) Rig sits another month and we pull it out to do some maintenance including DIY fix of a fogged drivers side window.
8) Change fuel filters and run the engine at high idle - All Wonderful.  I am brilliant.
9) Take it back to storage and dang it - It is sluggish and the lights/buzzer come on.  I double check the batt connections and go buy battery cleaner and protector.  Wire brush the connections - the whole 9 yards!
10). I run it some trying to diagnose it - EVEN THE JAKE isn't working properly now.  The dog gone thing says it is in "2" (never had the tranny say anything but 6) but the Jake is doing nothing. 

Any ideas or throw in the towel and take it to a mechanic?????  Even if I take it to a mechanic I would like to have some idea what might be wrong.

Desperate here as we have a trip coming up!!!!  I have about 9 days to get it fixed.  tick tick tick..... :-[. Maybe I am not so brilliant! :-[

 

[8Muddypaws]

loose ground strap to the engine can cause all sorts of unpredictable stuff.

Loose connectors to the control computer(s).  I've never had to find it but I've read there is an electrical connectors on the top of the transmission.  You might have a sticker on one of your bay doors indicating that the computer connectors are inside.  Maybe not too.

Personally I think I'd check what I could get to easily and if that doesn't work take it to a shop you trust.

 

[cerd]

You can try adding some ground jumpers to vital components, but I would also check your vacuum lines. It is possible that you have an intermittent leak. You could also put a multimeter on the battery while driving to see what it is doing. Monitoring tools are your best friend when it comes to diagnostics. If you don't have the proper tools, it may be better to bring it to a professional. Cheap tools dont perform very well either. If you have good ones, use them and see if anything pops out. Otherwise, bring it in.

 

[Kevin Means]

Here's another suggestion... A few months ago, we were climbing a mountain grade in very strong winds and pouring rain. The rain was blowing so hard from the side that the wipers could barely keep up with it.

About half way up the grade, my Freightliner information center lit up like a Christmas tree. The Check-engine light illuminated, yellow, then red warning lights acme on, and within a few seconds the stop engine light illuminated. Then the engine de-rated itself to 70%. I've got a Silverleaf system that displays every parameter about the coach's systems, and despite what the Freightliner info-center was saying, the Silverleaf system was was indicating that everything was in the green - all OK.

I pulled over, shut the engine off for a minute, then re-started it. Afterwards, the Freightliner info-center indicated that everything was OK. when I got home, I called Freightliner and they said that there are two connectors between the engine and transmission. One is a 72 pin connector and the other is a 16 pin connector. The tech-rep said it sounded like the 16 pin connector got wet and started sending erroneous info to the computer. I never saw those indications before or since. If ypur coach has similar connections, you might want to take a close look at them.

Kev

 

[KandT]

Thank you all - entirely possible wetness and computer errors are likely - in Pennsylvania it has rained for what feels like forever straight!!!

A loose ground??  But there are only like 500 of them and 27 miles of wire - augh!! ???

I love to problem solve but this one probably needs a white flag thrown up from me. :-\

I am guessing it is not the Heiu pump or else it probably wouldn?t be so intermittent.

My guess is the time to diagnose will be my big expense.  Then again I could be wrong and it?s the heiu pump. 

Augh augh augh.

 

[cerd]

A loose ground??  But there are only like 500 of them and 27 miles of wire - augh!! ???

You don't need a ground everywhere, just the critical components. Primarily the engine and the computers.

 

[Alfa38User]

But remember that today's dashes are plastic so you may find several healthy sized wires going to bolts on the metal under structure.

A number of years ago I had one intermittent problem that took me 3 years to find. It turned out that the car manufacturer had NOT bolted the ground in but the ring connector was simply jammed in under a wire bundle. Caused  lots of strange problems!!!

 

[KandT]

Just a partial follow up.  Took it to a real mechanic today - He had a Tractor Trailer he was working on.

On the way there I flipped on the Jake Brake and couldn't get the thing back up to 40mph.  It was blowing lots of smoke.

No turbo.

Then I flipped the Jake again and it went back to just regular underperformance. 

I was glad to get it to the mechanics - For a while I was hoping it wasn't going to need a tow.

 

[ZinLuvR]

I'm currently having a jake brake issue.  I have the Cummins ISM 500, performance is fine.  The jake seems to have decided to have a mind of it's own.  Sometimes it works, and sometimes it comes on even if the switch is off.  It's at Cummins right now getting checked out.  They have found it's a multiplex problem, which they feel they can fix.  I hope so, the local RV shop, and the one my warranty will pay, doesn't have a clue.  If you have a multiplex in your coach, that may be the problem.  Just my two cents after 7 weeks of fooling around at the RV shop.  I'm lucky to have a Cummins Coach Care facility in the area.  They don't do extended warranty work, but they have gotten the job done for me every time I've been there.

 

[sightseers]

As with most computer controlled equipment,    the more computers you have...the more problems you have.

 

[KandT]

As with most computer controlled equipment,    the more computers you have...the more problems you have.

I have a friend that is a coder for a big company. 

I said why does my personal computer have so many (daily) bugs and the ones in my car are pretty reliable.

He said it is because of the number of functions they are asked to do.  For example, my home computer runs all sorts of different programs along with the internet and maybe even stream a movie.  A car will have a computer with one function - control the antilock breaking system.  period.

Now to Sightseers point, when they do fail a typical guy like me and a wrench can stare at a circuit board all day and get nothin

 

[8Muddypaws]

If only it were that simple.  There are dozens of processors tied together in a complex network.  Every contemporary vehicle is a rolling distributed system. 

Not to spread fear or anything but some of the software was probably created by Microsoft and/or Apple.

 

[cerd]

If only it were that simple.  There are dozens of processors tied together in a complex network.  Every contemporary vehicle is a rolling distributed system. 

Not to spread fear or anything but some of the software was probably created by Microsoft and/or Apple.

When it comes to system controllers, they are actually FPGA chips that are often written by the electronics or firmware engineers for a specific purpose. Some engineers are more competent than others.

 

[KandT]

information is leaking out in drips!  Mechanic called.  Said it was a not anything like the HEUI or the Turbo Unit. 

It is an electrical problem.

He said there is an electrical issue that is causing the engine to "derating" itself.  I might be wrong on the term but apparently it reduces its HP because something is wrong so it doesn't damage itself. 

He said something maybe a solenoid in the turbo.  WAY past this weekend DIYer.  Repacking my dolly bearings for the first time this weekend was enough learning for me.

Anyways, he said he will look at it tonight.

Being a diesel mechanic when it is busy must be a rough life.  Sounds like this guy works all the time and when a tractor trailer is down the owner is losing money.  I am sure they get testy waiting too long. 

Fortunately, I feel blessed to have found a guy who seems honest and responsive.  Now I just have to understand he has a tough job when he hands me the bill! ??? ??? ??? ???

 

[ZinLuvR]

The way the tech at Cummins explained it to me, the jake is getting information from several sources all linked through the multiplex.  There is a bad actor putting in bad information on this electronic highway that is causing the jake to have a mind of it's own.  The problem is tracking down that bad actor, something I would not even attempt to do on my own.  There is a rack of "stuff" with blinking lights and switching going on in a closet which occupies about 10 square feet of wall space.  Up front there are circuit boards and relays with about 2000 white wires.  This is just the stuff I can see.  In the engine compartment there are more boards and blinking lights.  :-\  The tech is earning his money, that's for sure.  What happened to the days of keeping it simple?

 

[KandT]

So I bought this rig in October last year.  IS there a chance it has been running sub-optimally the entire time?  A Pennsylvania hill would really slow it down.  I drove it about 7000 miles.

 

[KandT]

Ok - So in keeping with my pet peeve of following up on the solution.....

I have to be honest, I couldn't follow the mechanic.  Something with a turbo gate getting stuck and a computer chip.  He said that it came from leaving it out and not running it enough.  Pennsylvania is just plain hard on equipment when left outside.

I should have it back on Thursday and for about $1000 including an oil change.  He said he was going to give it a good run before I picked it up.  I asked him if he were me would me would he do any other preventative maintenance.  He said run it more and store it inside. ??? ???

Inside storage here for a 36 foot MoHo isn't cheap but neither is fixin' it!

 

[taoshum]

IMHO, 9 times out of 10, if it involves a computer of any sort, the first step should be to reboot.  Power it down, let it sit for a few, then restart it and see what happens.  Computers, routers, tablets, phones, controllers... whatever... all it takes is a few bits and the crazy things go nuts.  Now, we know that just a while ago it was working fine so let's get back to that point.  If it repeats, or if this doesn't help then the 1 in 10 solution will probably require some help or something, like the ground wire, broke.

Just my 2 cents though.

 

[KandT]

IMHO, 9 times out of 10, if it involves a computer of any sort, the first step should be to reboot.  Power it down, let it sit for a few, then restart it and see what happens.  Computers, routers, tablets, phones, controllers... whatever... all it takes is a few bits and the crazy things go nuts.  Now, we know that just a while ago it was working fine so let's get back to that point.  If it repeats, or if this doesn't help then the 1 in 10 solution will probably require some help or something, like the ground wire, broke.

Just my 2 cents though.

Agreed!  The problem as a DIYer at my level is I am standing there not knowing what wire to pull or how to reboot any computer.  In this instance, it sounds like their were multiple issues.  Way past my ability.

 

[Lou Schneider]

Disconnecting the battery will  power cycle every computer in the vehicle.  You probably did this while cleaning the battery terminals.

The engine computer will reset to it's default values and will have tol re-learn the optimum parameters for your engine the next time you take it for a drive.