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Open Roads Forum  >  Class A Motorhomes  >  Maintenance Issues & Tips

 > ISB 6.7L - Reduced power and fuel mileage

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offthewall

New Jersey

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Posted: 06/08/14 04:05pm Link  |  Quote  |  Print  |  Notify Moderator

I have a 2010 6.7L ISB in an Itasca Meridian RV. 11,000 miles. Usually towing a 5,500 lb Jeep, 4 down. This will be the forth season of use. Yearly maintenance has always been done by the dealer.

On our first trip out this year, fuel mileage was down 2 mpg from what we usually get but performance otherwise seemed normal. The second trip out this weekend, fuel milage was down to 7-8 mpg on a trip we usually get 10-12 mpg. Power, acceleration and hill climbing ability was severely down. Grades where I could usually hold 55-60 mph, dropped to 40mph. On one long hill the digital display briefly showed "Engine Coolant High Temperature!".

The engine otherwise sounds and performs normally. It almost seems like the tubo-charger isn't kicking in on acceleration or hill climbing.

Any suggestions other than visiting a Frieghtliner service center?

Thanks.


2010 Itasca Meridian V Class 34Y
NJ tag: "THE RV"

2012 Jeep Wrangler Rubicon Unlimited Toad
NJ tag: "BLKJEEP"


Trackrig

Spent the summer in Conconuly, Wa, MH now in Vanco

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Posted: 06/08/14 04:10pm Link  |  Quote  |  Print  |  Notify Moderator

And the air cleaner has been changed as part of the maintenance or is in reasonable condition?

Bill


Nodwell RN110 out moose hunting. 4-53 Detroit, Clark 5 spd, 40" wide tracks, 10:00x20 tires, 16,000# capacity, 22,000# weight. You know the mud is getting deep when it's coming in the doors.


sjholt

Henderson, NV

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Posted: 06/08/14 04:32pm Link  |  Quote  |  Print  |  Notify Moderator

Ya might have a squirrel nest in that air cleaner?


Skip
1996 32' Monaco Windsor DP
Cummins 5.9L 230+ HP
5 Airbags in front- 4 in back

ScottG

Bothell Wa.

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Posted: 06/08/14 04:45pm Link  |  Quote  |  Print  |  Notify Moderator

Also make sure none of the boots in the plumbing between turbo and intake have come loose.


Scott, Grace and Wesly
2003 Dodge 3500 4x4, 6 speed Cummins (lightly bombed),
2004 Forest River 25RKS many, many mods.
H0NDA eu2000i

BobandShaz

New Mexico

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Posted: 06/08/14 04:48pm Link  |  Quote  |  Print  |  Notify Moderator

Trackrig wrote:

And the air cleaner has been changed as part of the maintenance or is in reasonable condition?

Bill


Sounds like air cleaner. I also read something about bio diesel going bad over time. I can't find that info right now but I will keep looking.


Bob and Sharon

2006 Winnebago Sightseer 29R Ford F53. Roadmaster Eagle 8000. 2001 Ford F150 7700 4x4. Still shopping for toad brakes. FMCA F286179


JumboJet

Tontitown ARKANSAW

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Posted: 06/08/14 05:03pm Link  |  Quote  |  Print  |  Notify Moderator

A good set of gauges to monitor the engine would be helpful - EGT gauge & Boost gauge. You can tell a lot with those two gauges.

I had a similar issue with a 6.7L and the problem was the turbo speed sensor. $100 part and $100 labor to replace. The problem did set a code.

powderman426

N. E. Ohio/The Villages, Fla

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Posted: 06/08/14 05:10pm Link  |  Quote  |  Print  |  Notify Moderator

JumboJet wrote:

A good set of gauges to monitor the engine would be helpful - EGT gauge & Boost gauge. You can tell a lot with those two gauges.

I had a similar issue with a 6.7L and the problem was the turbo speed sensor. $100 part and $100 labor to replace. The problem did set a code.


And the cheapest way to get those gauges that I have found is the elm327 odbII port reader and a tablet or smart phone. Less than $20 for the module and the app called Torque. Just look on EBay. BTW you should be able to hear the turbo spool up.


Ron & Charlotte
WD8CBT since 1976
32' Gulfstream Ameri-Camp & 05 Ram QC LB

I started with nothing and I still have most of it left

I never fail, I just succeed in finding out what doesn't work


wolfe10

Texas

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Posted: 06/08/14 05:30pm Link  |  Quote  |  Print  |  Notify Moderator

With loss of power on a diesel:

Change fuel filters.

Change air filter if air filter minder indicates high restriction or if over 3 years old (i.e. if OE, replace it).

And, absolutely, check for loose clamps between turbo and engine, particularly at CAC (Charge Air Cooler).

If all the above have been done and problem persists, off to a Cummins dealer.


Brett Wolfe
2003 Alpine 38'


FMCA Forum: www.community.fmca.com/index

Diesel RV Club:http://www.dieselrvclub.org/

randallb

On the road

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Posted: 06/09/14 08:10am Link  |  Quote  |  Print  |  Notify Moderator

There is a chance the VGT is not working correctly.
Randy

mchero

Off-Grid Quartzsite AZ

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Posted: 06/09/14 10:27am Link  |  Quote  |  Print  |  Notify Moderator

Also, If all checks iout the CAC "might" have a hole in it. Yes, check ALL the piping. My 8.3 lost a boot & it feels like it has 1HP! LOL

After reattaching the boot & tightening all was back to normal.

Oh, Do you have an Exhaust brake & could it have stuck closed?

RM

* This post was edited 06/09/14 10:41am by mchero *


Robert McHenry
Currently: Yuma AZ
2007 Fleetwood Discovery 39V
2005 Jeep Grand Cherokee
Prior:1993 Pace Arrow 37' Diesel
My personal website;
http://dieselrvowners.com/forum/index.php

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