cat c7 power loss- need suggestions

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.

(wide guess) Look for an air hose that didn't get put back on or is sucking air from atmosphere. Could be nothing more than a clamp that didn't get tighten.

A failing pressure sensor, ambient or manifold, could work normal at your home elevation but throw the fueling off at higher elevation.

The freightliner shop should have the diagnostic equipment to look at sensor output.

While a$$ guess, blown intake gasket.

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

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

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

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