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Livin2ride · 12-19-2018, 08:08 PM

have a 2005 mountain aire 4304 w 52k. bought it new. I know all its quirks. Has the 400 hsp ISL w 03 emisions. Spartan chassis. Early this summer I had it suddenly lose power when goin up a steep grade. I mean it would "bam" go into what i would call a limp mode. It was like the turbo suddenly turned off. It would manage to get up the hill and start acting right until the next big grade. It seemed to act up worse when I had a trailer attached. It never acted like it was missing or blowing any black smoke. Didnt matter if i had cruise on or off. It would just lose about 1/3 of its power. I have replaced both fuel filters and had it scanned at a authorized Cummins dealer (engine and allison trans) w no codes. serviced the transmission too. I saw on here where Kramer boy described the exact same symptom and cant find out what he did to correct it. What ever it is the OBD is not noticing it or recording it. I own a automotive repair service but dont really specialize in diesels. It used to only do it when it was ran 60 to 70 miles but now its doing it more frequently. My lil nightmare that keeps me awake at night lol. I just joined this site and I would appreciate any help. Thanks

Ray,IN · 12-19-2018, 08:55 PM

It's unfortunate we meet under this cloud of misfortune.
It sounds like this only happens when the turbo must work hard.

I suggest you closely inspect the rubber connections/boots on the post-turbo piping, spraying with kids bubble solution is IMO the best method of spotting a pressure leak. Re-torque the boot clamps to spec while in there.
Do you have a way to monitor turbo boost pressure?
Another potential issue would be the air filter, if you haven't changed it in several years it could be reducing total air flow. The air filter monitors have been known to fail, some models can be rebuilt, others must be replaced.

Dutch Star Don · 12-19-2018, 09:27 PM

It certainly sounds odd, especially since it's not throwing any codes. I would also suspect an air intake issue. Possibly a filter deteriorating or the air pick up tube could have come loose and has fallen to one side. If the air cleaner is fresh, try disconnecting the large tube coming down from the roof edge, to the air cleaner, and see if you still have the issue.

Breezy2006 · 12-19-2018, 10:24 PM

Had this on a 06 MADP. I think it is your injectors. Hopefully just one, they are not cheap. Take it to a Cummins shop and they can test for this.

Dav L · 12-20-2018, 10:11 AM

Within the engine controllers software, there are "one trip" and "two trip" failures. You might have the failure and it hasn't occurred for long enough or enough times to create a Diagnostic Trouble Code.

doesn't sound like an injector to me. Because that is typically not intermittent and not the whole bank of injectors at once and if only one, won't cause that much of a performance problem.

Fuel filter? Crap in the fuel tank? Water? Much higher odds.

Possibly trailer related because you are using more HP which means more fuel needed, which means if there is a partial fuel restriction then you will be running lean and generating far less power than what the engine is normally capable of.

I would pull the filter and pour it out into a clean container and inspect. Something that should be done normal maintenance anyway so no loss of $'s or time.
Certainly also do a physical inspection for turbo hose cracks, loose clamps, and the like which should be done all the time to ensure you don't dust the motor.

Note that if this is a diesel, it's not OBDII so your auto scan tool won't work at all. Invest in a scan tool that will work for your rig and watch the real time data. If you are a diagnostician at your day job, then you should find the data in the graphs the scan tool will generate. Diesel or Gas...same process.