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Cummins 275 hp ISB diesel does not want to rev higer than 1400 rpm


PaulKarman

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Hi, I'm new to Rv'ing, diesel engines and this forum. I hope I posted this at the right place or otherwise someone can help me find my way?

 

We just bought a 2002 Winnebago Journey, a 275 Hp diesel pusher, with what I think is just a small problem, and I realy hope I am right....

 

Sometimes, with increasing regularity the unit is not drivable just after starting. The engine idles at 650 rpm or so and after pushing the gas pedal it jumps up to 1400 rpm. It is not possible to rev the engine higher or lower. It's either 650 or 1400 rpm. After some time the engine reacts back normal on the throttle. Sometimes it takes longer sometimes shorter, sometimes it takes a restart, sometimes it does not. Sometimes the problem is back directlly after restarting and sometimes it is not. Of course we let the machine warm up while running idle for a while but temperature does not seem to be a factor. Lucily the engine has not relapsed on us while on the road.

 

Since the problem is so nicely reproducable and the rpm's realy stabilise so nicely and quickly at 1400 rpm I don't think it is a mechanical problem. It feels like a design feature that I am yet to be made aware of.

 

Somewhere I read about protection circutry that prevents a diesel from revving whenever there is anything connected that needs to be protected against higher rpm's. For instance to protect a hydrolic pump that can not handle the high rpm's. But I'm not sure whether and how this would apply to our Winnebago Journey.

 

Does anyone have any idea on what to look for. I am reasonably handy but for now I am totally unfamiliar with our beautiful diesel pusher.

 

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Find a place to have the fuel filter changed. What make engine? My cummins is picky about brands. Find a Speedco and get it serviced and all filters changed. Watch how they do it and purchase a spare fuel filter to carry with you. After the filter change let us know if it is any different. Also do you have a turbo? If so is your boost gauge showing boost?

Ron C.

2013 Dynamax Trilogy 3850 D3

2000 Kenworth T2000 Optimus Prime

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Hi Ronbo, thank you for your quick response.

 

We intend to have the RV serviced but we'd rather have the problem sorted out or at least be a bit more knowledgeable about it before we take it in for a service. We don't want to be sold all sorts of "might solve the problem" solutions that have nothing to do with the problem.

 

One such things could be the need to replace filters. I would think an fuel filter is either clogged or not. I would expect the engine to run bad all the time with a clogged filter. This engine does not. In fact, it runs prefectly most of the time but the throttle acts like a switch between 650 and 1400 rpm when the problem occurs. Do you think this can be solved with a filter change?

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Hi Trailerking. I do have an OBD2 reader but I have not looked for/found the ODB connector yet. I intend to find it if only because I am that kind of nerd who likes to see lots of gauges and stuff on my Torque app. I have not looked into it yet because I would expect a bad TPS to work irrationally, jump between all sorts of rpm's and not like a switch between 650 and 1400 rpm. But who knows, it might be some build in fail safe behaviour for a bad TPS? Definitily something to look into.

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Get a VMSpc for it. The 650 to 1400 problem is very unusual for a ISB.

First problem like that I have seen in over 14 years of different forums use.

 

Tap that up idle button until you get 700 and see it that fixes or changes your problem.

 

On mine I can change the RPM from the 650 to 2500 when in "N" or "P" and anywhere in between.

You should also be able to set your cruise control to set at any higher RPM while in "P"

Full Time since Oct. 1999
99 Discovery 34Q DP | ISB
Datastorm | VMSpc | Co-Pilot Live | Pressure Pro
2014 MKS Twin Turbo V6 365 HP Toad
369070033.jpg

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Could be a problem with the throttle position sensor. Do you get any error codes?

I was thinking that while reading down to your post. It's the most obvious.

 

2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG retired;Good Sam Life member,FMCA ." And so, my fellow Americans: ask not what your country can do for you--ask what you can do for your country.  John F. Kennedy 20 Jan 1961

 

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As suggested above I would have all of the fluids and filters changed soon at a service center that specializes in your engine if for no other reason than to establish a base line. We have a Cummins M11 and often will get our oil changed at a Cummins shop and have them inspect the engine for repair/replacement items. I like the shop that allows me to be near the coach when the inspection is occuring so I am aware of anything the they might find. As I am not familiar with your engine I would suggest that you take it to a truck service facility and have them check it out. When our oil is being changed we have a sample taken and sent out for analysis. The reaults will tell you the condition of the engine. The Cummins shops that we have visited have been very professional and have NOT taken advantage of us. We do not take our coach to any RV service repair facility.

 

We also use a VMSPC.

 

Good luck and travel safe. :D

Scott & Carol Seibert + Harley Lil Pup
2002 U320 36' PBDS
Build# 5954 MC# 17212
2014 Jeep Wrangler Unlimited Sport

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"We also use a VMSPC"

I have the USB version and can report it runs fine with 32-bit Windows 10. Just thought others would want to know they can upgrade to Windows 10 and keep VMSpc on a 32-bit laptop. I have no reason to run it on a 64-bit Windows machine, where installing the driver has been a complicated procedure.

 

Now back to on topic replies.

2004 40' Newmar Dutch Star DP towing an AWD 2020 Ford Escape Hybrid, Fulltimer July 2003 to October 2018, Parttimer now.
Travels through much of 2013 - http://www.sacnoth.com - Bill, Diane and Evita (the cat)
 

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There is a generic TPS test. Remove the sensor, measure resistance at rest/closed position. Then measure resistance at WOT position, then slowly allow it to return to the closed position. There must be an even slow movement of the measurement from WOT to closed, or the TPS is faulty.

Although not your engine, this utube video may explain a lot.

 

2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG retired;Good Sam Life member,FMCA ." And so, my fellow Americans: ask not what your country can do for you--ask what you can do for your country.  John F. Kennedy 20 Jan 1961

 

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