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crawbob · 12-07-2013, 12:16 PM

The only thing that hasn't been replaced is the wiring harness. Even the droping resister for the computer was replaced. The low boost took over 6 months to occur. It wasn't quick. The exhaust is a straight through, no restrictions, K&N type of intake filter, no restrictions.

McRvnut · 12-07-2013, 12:33 PM

what happens when you block off the actuation arm(pinch off vacum feed) will the turbo pressure go high?if it wont then I suspect bad turbo?banks people taught me that one test
also like I suggested have u checked the ex brake to make sure its not partially closed

crawbob · 12-07-2013, 01:30 PM

Nothing we have tried has increased turbo pressure, including the turbo hose being pinched. Cummins West, now Cummins Pacific is the main warrantee facility for Cummins USA. There is no one that is supposed to be better or more update then they are. They have all the latest test equipment. It has spent many hours on their dyno etc.

McRvnut · 12-07-2013, 01:36 PM

Quote:

Originally Posted by crawbob

Nothing we have tried has increased turbo pressure, including the turbo hose being pinched. Cummins West, now Cummins Pacific is the main warrantee facility for Cummins USA. There is no one that is supposed to be better or more update then they are. They have all the latest test equipment. It has spent many hours on their dyno etc.

well this tells me in my very limited cummins turbo knowledge that either the turbo is no good or the exhaust supply is not adaquit to allow turbo to boost
properly like a exhaust leak at manifold or??

crawbob · 12-07-2013, 01:45 PM

The exhaust manifold was replaced. No change. There is no leak in the system, intake or exhaust. The EGT is low, about 800 degrees, showing there is not enough fuel getting into it to turn the turbo up. The system has been pressure checked and no leaks.

crawbob · 12-07-2013, 01:49 PM

This is a unusual problem, nothing standard will work. Every thing has been checked and double checked. It was in the Cummins facility for two years straight. If it was something normal I think they would have found it. They wanted to get rid of it. They had to store it in a covered garage and needed the room.

McRvnut · 12-07-2013, 01:56 PM

Quote:

Originally Posted by crawbob

This is a unusual problem, nothing standard will work. Every thing has been checked and double checked. It was in the Cummins facility for two years straight. If it was something normal I think they would have found it. They wanted to get rid of it. They had to store it in a covered garage and needed the room.

WHY would you spend thousands upon thousands of Dollars and let it sit for two years?? should have traded it off and saved thousands of dollars

palehorse89 · 12-07-2013, 02:01 PM

Quote:

Originally Posted by crawbob

This is a unusual problem, nothing standard will work. Every thing has been checked and double checked. It was in the Cummins facility for two years straight. If it was something normal I think they would have found it. They wanted to get rid of it. They had to store it in a covered garage and needed the room.

They had your Coach for 2 years!

WT_ ! Not to be rude here......if you can live with your Coach being at a Cummins dealer for 2 years and this problem has been going on for 6 years you obviously do not use it to much........Do as they did "get rid of it"

1985 Bounder · 12-07-2013, 02:23 PM

When it is on the Dyno does it pull the proper horsepower and torque readings? If it is to spec then the fact that the boost is on the low end of the spec is probably not your problem.
The newer turbos run faster and hotter than the old ones did. Because of this the turbine housing (exhaust) tends to crack in various places, including around the waste gate port allowing leakage even without the valve being opened. If they used a rebuilt unit when they replaced yours it could also have this issue because this does not cause the turbo to be out of spec. Another issue I have seen is the inlet tubing from the air filter to the turbo will separate and the rubberized interior will collapse while the hardened plastic exterior retains it's shape. In older engines this would give you a smoking issue but in today's electronic world the computer senses less air so allows less fuel. McRvnuts recommendation about the exhaust brake being closed or partially closed could also create the same issue on the exhaust side. I would also have Cummins verify that you have also gotten the latest version of the turbo as there are constant upgrades to address performance and durability issues. They should also run the engine serial number to get all the service bulletins and check for power and boost issues. My last thought is that your turbo may be a variable vane unit. The flow of the turbine housing is controlled by vanes built into the housing. These vanes can become stuck or partially stuck, and/or the module that controls them can be defective or misadjusted. They should be able to test the vanes when they have the computer hooked up to it. In your case they may not be closing all the way, not allowing the turbo to reach maximum boost. Hopefully they have checked all of these things but at least you can ask very specific questions.

rickf · 12-07-2013, 03:12 PM

With all due respect to the OP, You came here looking for answers and every single answer you were given you shot down. You tell us it is at the best Cummins dealer in the country with the newest and best diagnostic equipment, What more can you expect us to tell you? You have replaced every single external part of the engine. I have heard nobody mention a compression test yet though, could be an internal problem with the engine but I am going to bet you are going to come back and say They did that and it was normal. My first guess would be the same as was already mentioned about the rubber boots on the turbo outlet going bad inside. I have had that happen myself and it is a bear to find sometimes since it only shows up at max boost. Not a time when you would want to have your head in there. If this is a warranty deal I would have invoked the lemon law years ago! Good luck with it and I certainly hope the issue is found soon.

Rick

McRvnut · 12-07-2013, 04:30 PM

SO tell us what was the final bill?? New fuel tank installed, new lift pump installed, new exhaust manifold installed,New turbo installed, new ecm installed,new CAC installed
New Fuel injection pump installed,new FP switch changed,6 new fuel injectors installed etc etc I am at $17000.00 estimate and counting

crawbob · 12-07-2013, 06:56 PM

The dyno readings a down about 25% and the turbo housing is OK. They can't do a compression check but they did a leak down test and it was less than 5% which is very good. It dosn't smoke or blow any oil out of the breather tube. I am asking for help because this is an unusal problem which can't be fixed under normal conditions. I have had 2 Cummins service enginners trying to find the problem with no answer.

McRvnut · 12-07-2013, 08:18 PM

Quote:

Originally Posted by crawbob

The dyno readings a down about 25% and the turbo housing is OK. They can't do a compression check but they did a leak down test and it was less than 5% which is very good. It dosn't smoke or blow any oil out of the breather tube. I am asking for help because this is an unusal problem which can't be fixed under normal conditions. I have had 2 Cummins service enginners trying to find the problem with no answer.

so tell us how much money have you spent on this deal?

crawbob · 12-07-2013, 08:43 PM

Over $10,000. But at least I am able to deduct it off my taxes. I did use it every month and had free covered storage for 2 years and saved on diesel fuel on 300 miles each month.