400 ISL loses power on long hills

[Steve Ownby]

Originally Posted by FreedomDream

Take it to Cummins certified service center who can check turbo boost, read codes and check over all performance. Make sure you tell them about the manifold work you had done and who did the work. They may nee to check to see if correct part was installed. Good luck.

Since your original post says that the performance loss was "immediately noticeable" then it should be assumed that the work performed is suspect. FreedomDream is correct about the direction forward.


Steve Ownby
Full time since '07

[roadwarriorz]

I also agree something is wrong. My 34,000 lb. Diplomat with 400 hp ISL would also climb a long 6% grade (Cajon Pass) at 60 mph...

[Lloyd in S.C.]

Not much info in your post? Year?

The 400ISL don't have a waster gate. It is a variable geometry turbo. You mention manifold? Exhaust manifold? Has the turbo been reinstalled?

L.

[Smitty77]

Originally Posted by Lloyd in S.C.

Not much info in your post? Year?

The 400ISL don't have a waster gate. It is a variable geometry turbo. You mention manifold? Exhaust manifold? Has the turbo been reinstalled?

L.

His profile reflects a 2004 American Dream. Very possible this is the CAPS era ISL, not Common Rail with Variable Geometry Turbo. Only way to know for sure, is to have the build checked vis SN with Cummins.

I know this how? Well a bit sheepishly, I admit I drove our coach for well over a year, before a conversation with Cummins Tech Support on another issue, revealed my coach had the CAPS era ISL. The engine was built in July of 2003, and the coach was built in Sept of 2003, as a 2004 model year. It was on me, to validate that I was getting the newer engine, that I desired.

X's 2 on going in and getting it tested with the computer reading codes.

Please circle back and let us know how it tuns out. And, best to you,

Smitty

[jdbunch0924]

I agree that you need to have Cummings put it on a dynamo machine. We had problem with our Allegro Bus 330 Cat loosing power around Salt Lake City. We had replace fuel and air filters before we left on trip. That was first thing Cummings checked when we took it in. I had them put it on dynamo after everything else checked out. It turned out that the fuel filter housing had a hair line crack and as the engine was put under load and heated up the crack would open and allow air into the fuel system and caused a loss of power. Coach ran great after new fuel filter housing replaced. In other words problem would probably never have been found if it had not been put on the dynamo.

[Rich-n-Linda]

The company name is CUMMINS, not CUMMINGS!


2006 Mandalay 40E, Cummins ISL 400 HP

[RIDER FAN]

I believe you may have a bad lift pump. Lift pump on 400 ISL should have 5 lbs pressure.
I experienced the same symptons with loss of power on hills. My lift pump was only putting out 1.5 lbs pressure. Changed it and all good.
Also you may have an additional in line fuel filter along frame. I don't know exactly where its located ,[my Endeavor does not have one ] I just heard of a guy that had similar restricted fuel problems and the shop changed everything...........until another shop found the filter that was indeed the culprit.

[ru499]

Originally Posted by Rich-n-Linda

I have the 400 hp ISL in a 34,000 pound coach. I routinely run 5 and 6% interstate grades in 5th gear at 65 mph and 2,000 RPM.

40 mph is way too slow. Something IS wrong.

I agree. My400 ISL pulls our 3400 lb car up 7% grades holding 55 mph in 5th gear.

[Wilkiesr]

Do you see any black smoke when it gets down to pulling hard?

[Sky_Boss]

Where does someone get a dyno? I've been told by a couple places they won't dyno a loaded chassis.