Turbo on when idling?

[anniemae]

Yesterday while re-sorting storage area (2010 Monaco Diplomat 42 SKQ 425 hp Cummins) I started the engine and then the generator to charge the batteries. MH is in storage for a couple of weeks before we hit the road again.  No shore power. Lost track of time, and heard the idle speed increase for a few moments. Went inside and saw Boost increase from 0 to 3 or 4 psi. I had one AC unit on to exercise generator, shut it off, let geerator idle a few minutes and then shut it off then few minutes later the engine.  I belive the turbo had cut in.  Made me nervous not knowing what was going on.  This DP is new to me,  Alot to learn.  Thoughts?

 

[topdownman]

Well, the turbo is running if the engine is running.  It's powered by exhaust gases.  So, if you have exhaust, the turbo is spinning.

 

[commkruge]

Dont panic the turbo runs all the time. Diesels will kick their idle up once sitting for a couple minutes this is normal. The charging system requires a higher rpm. Also when parking after a drive let it idle for a few minutes it will kick up to a high idle then down to cool the turbo. My freind has a DP dutch star I went to test run for them it does the same thing. It would do you good though to pull the manual and look at the ref area on idle times. Some units need the cool down idle and some you can shut right down. They are a little different but once you get used to the way they act all the worries will be gone.

 

[Gary RV_Wizard]

Are you sure it was the coach engine that speeded up? The generator would do that normally, in response to loading.

Or it could be the coach engine, responding to its own needs such as cooling requirements.  It's not that the turbo cuts in and increases engine speed - it is actually just the opposite. The engine computer calls for an increase in engine RPMs and that "acceleration" cause the turbo boost to increase a bit. The turbo is always on, but does not generate boost pressure unless there is a need. Any increase in engine RPMs is considered "demand".

 

[driftless shifter]

I Don't know if this helps. Do MH diesels have the same EPA regs as class 4 and up trucks? Around 2010 diesel exhaust filters began showing up. They remove particulates (soot) from the exhuast. When the system detects a dirty filter at idle it kicks the idle up and restricts exhaust flow, makes boost, and the engine has to work to keep the rpm up. The exhaust temps rise and burn the soot out of filter. This can happen any time the engine is running, at start up, at traffic lights, idling at a delivery. There should be a sticker on your sunvisor, glove box, or somewhere in the cockpit, explaining it and showing what the idiot light looks like etc... It doesn't affect your ability to drive, light turns green and off you go.

Then there is diesel exhaust fluid (DEF)! This came out last year? About 1000lb worth of exhaust system comes with this one.

Bill

 

[anniemae]

Thank you all. Yes Gary it was the engine.  I understand the turbo running all the time, it was the obvious increase in rpm that got my attention.  The boost psi was only 3-4 psi.  I recall seeing the boost psi around 6-8 on the hi-wy. Ive only put about 300 miles on the MH since purchase. We have several trips within Fl. the last3 wks in Feb./March.  Then March 25 th we leave for Texas and the Rockys back home in Nov/Dec.  The driving is easy but much more to learn than required with our gas MH, especially the electrical.

 

[Gary RV_Wizard]

My guess is that the engine computer (ECM) decided that more cooling was needed, so it increased engine rpms to drive the fan faster.  A diesel is a hot running engine and the cooling system has relatively little capacity at low rpms. It may also increase rpms if the dash a/c kicks on.

 

[denmarc]

I have to agree with Gary.  Especially if MH's are equipped with the same clutch type cooling fans that Class 8's are.  Assuming so, if the ECM detected and called for more cooling, then I wonder if it's possible the clutch fan locked in and the noise of the fan is what alerted anniemae in the first place.  The RPM increase, and the additional noise to the untrained ear, this could sound like trouble to a new owner under certain conditions.  When in fact is normal.

I'm maybe thinking it was noticing the additional turbo boost indication on the dash guage due to the slightly increased idle called for by the ECM.  When checking out as to why after hearing the additional noise (possibly mistaken as the turbo) and the RPM's going up, resulted to the orginal question.

If engine temperature and all remained normal, and no other indications of a problem (leaks, proper coolant level, etc.), then I would suggest normal operation under the conditions at the time.

Just a thought that if I'm right, the cost of repair is zero.