Elevation = rough start up..?

Gnome

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Nov 20, 2019
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North Oregon Coast
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LS MT125
This past summer I transported my 2019 LS MT125 from sea level in Oregon to my Idaho mountain property at 3,200' elevation. Immediately cold start ups were rough and smokey. After a bit of warm up it smoothes out and all is good. Now that cooler weather is here the start ups have been noticeably rougher, to the point I believe the motor will just die. Hasn't happened yet, but definitely a concern. I've applied the ten second plug preheat, maybe more is needed...? Incidentally I've just 78 hours on the machine.
My thoughts are the map for the fuel injection needs to be upgraded... I have been under the impression ALL modern fuel injection maps were programmed for elevation changes. Any body have any thoughts on this and anyone operate at simliar elevation.
 

sea2summit

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Odd. Are your filters good/clear? What are the temps when this is happening? 3,200' shouldn't be a big issue for an injected system.
 
  
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Gnome

Gnome

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North Oregon Coast
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Filters changed at 48 engine hours in Oregon. Problem started immediately upon arrival in Idaho. Temps in June at start up were in 50˙ range, yesterday 28˙....
 

TMGT

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Being an idi diesel its a mechanical system, no programing or map to adjust. Since the fuel is at a set amount for rpm/throttle position it is getting more fuel then it needs at cold start since there is less atmospheric pressure.

Try raising the throttle slightly and run the glow plugs a little longer.
I think there is a fuel rack adjustment that can be made but not sure and would most likely need to be done at the dealer if its even possible.
 

Snobdds

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I use diesels at 10K feet in wyoming. There is no special injectors for this elevation, just give it some more air (throttle).
 

JasperFrank

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I don't think a difference of 2 PSI would have any effect on a fuel injected diesel engine. I suspect the starting is different due to temperature. I can't see any reason to remap. Maybe an oil heater would help.
 

sea2summit

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Filters changed at 48 engine hours in Oregon. Problem started immediately upon arrival in Idaho. Temps in June at start up were in 50˙ range, yesterday 28˙....
That is odd. Do you typically get it hot when you run it? You may be seeing some buildup in the system. Usually if I'm seeing frost I start adding the blanket to the truck if I'm not pulling something with it or driving a good distance and mid 20's is block heater time for mine. Diesel engines don't especially like to be cool let alone cold but modern glow plugs etc have made them a lot better at it.
 

LS Tractor Owner

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Edgewood, NM
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I had my MT125 here at an elevation of 7,000 ft..... yes it starts a bit rougher when cold. I used to hold the glow plugs for at least 20 seconds, the results were dramatic! Try it and see if it improves your startup.
 

JasperFrank

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I don't hold the glow plugs for more then 5 seconds, even at very low temps, like 28 degrees F. 20 seconds just seems to be over kill.
 

etpm

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yanmar ym2310
I don't think a difference of 2 PSI would have any effect on a fuel injected diesel engine. I suspect the starting is different due to temperature. I can't see any reason to remap. Maybe an oil heater would help.
Sea level air pressure is average 14.7 lbs/PSI. Let's call it 15. 15 divided by 2 equals 7.5 which can also be expressed as 13.3%. So that would translate into about 13.3% lower pressure when compressed in the engine. I dunno how that translates into temperature drop but less air compressed into the same space will have a lower temperature. I do know though that there will be about 13.3% less air available for combustion. So I guess max HP would be lower. But since the diesel engine types I'm familiar with, which are 40 years old or older, always compress as much air as possible since the air isn't throttled, it seems like there would be plenty of air at any setting below max fuel injection. So maybe less air compressed leads to lower compressed air temp which leads to harder starting.
Eric
 
 
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