I am from Tennessee and have driven this motorhome about 39K during the last 6 years of so since I bought it. I arrived in Denver Colorado about 2weeks ago. I noticed a very noticeable decrease in power when I arrived. I took the motorhome to the local Transwest Freightliner dealer that is an authorized Cat repair facility. I now have a new turbo charger, and a completely new set of injectors and a new wastegate controller. I picked up the motorhome today with the assurance that everything was fine. Something is definitely still wrong . It has very little power on acceleration and really just lugs along until I can get up to about 2000 rpm. I know I am used to the power back at home under 1000 feet elevation and I am now in Denver at about 5000 feet but have a hard time believing that the severe loss of power is entirely because of elevation. I am taking it back to the Freightliner shop tomorrow. The question is how much loss of power have you folks seen on a properly working turbo charged diesel at the elevations I am at here in Denver? I know I will see some but this thing is a real dog when starting off. I was going up a little rise from a stop light and had my foot to the floor and I did not think it was going to get above 1500 rpm and get out of first.Any suggestions or comforting words would be appreciated.ThanksStuck in DenverKen

Assume fuel filters have been changed?? No air in fuel lines??

We were up at Eisenhower Tunnel (just over 11,000'), Steam Boat (Rabbit Ear pass at 9,426') and Teton Pass (8,429' with 8 miles of 10% grades) earlier this summer and didn't notice a lack of power due to the elevation. We have a Cat C7, 350HP in a 2005 Fleetwood Excursion.Bill

Bill thanks that helps. and yes fuel filter and air filter have been changed. i did that before i took it to the shop.Ken

Ken, We just went through that section of Denver a few weeks ago. We have an '04 Itasca Horizon 36GD with the C-7 330HP CAT. We live in Lake Havasu AZ and, to the best of my rememberance, our coach performed in Denver, pretty much the same as it does in our home which, is not all that far above sea level. And, we're towing a 5300 lb. GMC Sierra 1500 4x4 truck. So, while you've had injectors, turbo, and waste gate have been changed, obviously there's something else wrong 'cause you're still experience a power loss. It has been suggested that the fuel filter(s) be changed too. We kind of assume that, they or, it, has been changed, based on one or two filters since not all C-7s are created equal. Now, while I've been around diesels for most of my career life, (about 36 years total in the fire service), I'm certainly no expert. But, one component that we had go bad on several of our fire trucks was the CAC or, Charge Air Cooler or, another name is the Inter cooler. Those are mostly made of aluminum and, because of the structure around them, they can crack, in multiple places. When that happens, you can have a ton of brand new turbo chargers and it won't do any good because, all the air your "turbo charging" is escaping out of the cracks or, crack, or hoses that attach the unit to and from the engine etc. And, you can have bad hoses or, broken clamps etc. Now, I'm not saying this is your problem. I figure those CAT techs pretty much know what they're doing and who am I to tell them what's wrong? But, it's a suggestion. I don't know if you or, they, (the CAT techs) are near a dyno, it's possible that you may be able to tell where the problem is. It might help you and, it might not. But, we, in the FD, could see when the cab was tilted up and, the engine running, and the clutch fan turned off, that, just like spraying a soapy solution over an inner tube from a bicycle to find a leak, or pressurize a gas/fuel tank to find a leak, we'd spray the inter cooler and see lots of bubbles emanating from multiple places. It meant we were loosing lots of charged (pressurized) air and, therefore, lots of power. And boy, could we tell it. Once the intercooler was either repaired or replaced, it was like a new engine had been installed. You see, sometimes those cracks or, breakages, happen over time and you loose the power, slowly but, do not really recognize it. So, anyway, maybe some of this info will help. Let us know if it get's corrected so that others (including myself) will learn. Scott

While a$$ guess, blown intake gasket.

cat c7 power loss- need suggestions | Good Sam Community

n4hwl
Explorer
Aug 17, 2014
Yep I am fixed and drove from Dennver to Moab. UT along I 70. The old ecm programming was not communicating with the new injectors ( I was told} The update on the ecm allowed the injectors to start working properly. All I know is that everything seems to be working. I have another 2 or 3 thousand miles to put on this thing before I get home. That should tell me if it is going to hold together.

Ken
Big_Katuna
Explorer II
Aug 16, 2014
He's fixed and on the road.
John_S_
Explorer II
Aug 16, 2014
Have they checked the CAC. A crack or leak there can reduce the power.
AH64ID
Explorer
Aug 16, 2014
They are blaming the WG on an ECM tune?
n4hwl
Explorer
Aug 16, 2014
I believe them when they said the wastegate was stuck open. This is the first time I have been at this altitude. I usually drive around the southeast usually below 1000 ft elevation. It is possible that the boost has been down a long time and driving at lower elevations it has not been a big deal. It seems to be running fine now. I am in Evergreen Colorado now and will head west on I 70 very shortly. I will find out up around the continental divide it the turbo is doing its job.

Ken
AH64ID
Explorer
Aug 16, 2014
Have you had the rig at altitude before?

I'm wonder if the ECM flash was the issue in the first place.
n4hwl
Explorer
Aug 16, 2014
Big Kahuna

I think if I have a choice next time I will go to the Cat dealer directly. At least Cat themselves should be up on their own engines

Ken
noteven
Explorer III
Aug 16, 2014
Most truck shops will not flash an engine ECM without the owner's permission. It is also good practice to ask them to check for updates and explain to you what the update is for before they do it.

Glad to hear the engine is fixed.
Big_Katuna
Explorer II
Aug 16, 2014
Thanks for the update and glad you are back on the road.
Sounds like another marginal Freightliner shop. I have not been impressed with any I have used.
n4hwl
Explorer
Aug 16, 2014
Final resolution to problem.

The problem this week is that old program in the ecm that seemed to be the one that was in it when the engine was built had never been updated. This old version in the ecm would not talk to the newer injectors and they were not working properly. I killed 4 days in Denver just because they did not reflash my ecm with the new software when they put in the new injectors. My question is why did they not know they needed to do this. Either 1. Caterpillar is not keeping Freightliner updated on what these engines need as far a software or 2. Caterpillar is keeping Freightliner updated and Freightliner is not keeping things straight. Well either way I am headed over the Rockies today and things seem to be working fine. Thanks for all the help

Ken

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