ISX rattles?

2005 ISX 475hp in an IH, 13 speed. This problem has gotten continuously worse. It has gotten colder also now. Like single digits! From sporadic to common now. Under no load condition it rattles or clatters terrible. Under load, as soon as you put the fuel to it, it stops. Until you get to the top of the gear, take the load off, it clatters again. Grab a gear, squeeze on the throttle, you can even feel a dead spot, then it hits and rattles til under load again. At times, after shut down for 30 min or so, or even idling for about that long, it stops clattering. Even has stopped doing it at a light, stayed quiet through a few gears, then started again. Fuel mileage has also dropped. When its in this 'mode' its even weak on clutch engagement and through the bottom gears too. Under load at full throttle it seems to get ok boost levels.

Hoping someone has experienced something like this before. Currently has no codes or faults showing. Last week had a code for the exhaust pressure sensor, replaced it and cleared the code. This has been going on now for a few weeks. Getting worse it seems. Only had this truck a little over a month and not liking it so far. Any help? Thanks!

 

Truck has 450k on it. And about 250k on a warranty overhaul (Cummins shop crushed the air inlet piping which then dusted the engine). The compressor is definately noisy, and can tell when its in or out. Does not seem overly noisy though and not running all the time.

In the shop today with it. Pulled the rocker cover for a looksee. All looks fine. Did run the overhead and some were off, either tight or loose, but not overly so.

This noise comes and goes at will it seems. MPG also lower. You can tell if its in that 'mode' so to speak even bobtailing in the yard. Also, at a stop, loaded, on clutch engagement it feels weak as it does through the gears then too. Even noticing a different sound on the jakes when its doing that. Weaker sound and feel. Then, the next run through, all is fine.

Late today, while discussing it at the shop, and symptoms, a similar issue was remembered on a same year ISX. Fault code showed once for a Barometric Pressure sensor. Similar symptoms. Supposedly this will affect timing and fuel. That fixed that truck. Although no codes now showing on this one, for $50, we're putting one on it. Fingers crossed!

 

After more and more tests thru Insite and checking everything supposedly the culprit is the turbo itself. Through Insite it failed the turbo self-test. Turbo test speed was low also.

On a test drive with it hooked up, it didnt repeat the problem right away, then after getting up to speed it started and showed on the laptop engine not getting boost, fuel being restricted, check air intake system. The charge air and boots are new, but tested them anyway. All fine. Replaced boost sensor. Some differences noticed. But problem still there.

In talking to a couple Cummins shops, both pointed to the turbo. New turbo ($$$$ ouch!) installed. Everything sounds different! Turbo whine much more noticeable. Not much of a test drive in 6 inches of fresh snow though. The 'clatter' at low load conditions is there still though just barely. Dont know if this is a characteristic of this EGR and variable turbo setup on these. Should be truckin tomorrow with a load on it and know more then.

Soon for sale
2005 IH 9900 Eagle Daycab, 475hp Cummins, 13 spd, 450k miles. Med/ dark blue, tan interior. Nice looking truck with lots of new parts!
I want my old yeller motor back!

 

In talking to a few owners of these, nobody had that rattle. The thing that is really bothersome, is that its so sporadic, and it affects the power when in that mode. And mileage is down nearly a full point now.

And, after they were sure it was the turbo, it still has the same problem. Now tried a new pair of timing actuators. On a short bobtail test drive, did not seem to change anything. Test it loaded tomorrow.

Not happy!