Elevation = rough start up..?

Cougsfan

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Perhaps I am wrong, but I thought a diesel most always operates with excess air (or O2) as the intake has no restrictions. You control the rpms or power with the "throttle" by giving it more fuel in the fuel injection charge rather than more air (like a gas engine). My guess is that this elevation change has nothing to do with starting but it is more temperature related. However Turbo chargers do help diesels at elevation more than at sea level as they can out of excess air at the lower atmospheric pressure and O2 levels under heavy engine load conditions.
 
  
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Gnome

Gnome

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Nov 20, 2019
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North Oregon Coast
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LS MT125
Thank you for all the responses. Yesterday, after fluids and filter checks and a lube job I fired up the little beast. Temperature was 38˙, but with snow flurries happening I suspect colder. With 15 seconds on the glow plugs and a slightly elevated throttle ignition was immediate, as always, but again, warm up was rough for about 45 seconds. It did smooth out a bit quicker, probably due to increased throttle, which was only about 500 rpm above usual idle. Machine ran great after a ten minute warm up at normal throttle.
 

SPYDERLK

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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).

Diesel throttle controls fuel. Air is never restricted.
 

SPYDERLK

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JD2010, Kubota3450,2550, Mahindra 7520 w FEL w Skid Steer QC w/Tilt Tatch, & BH, BX1500
Perhaps I am wrong, but I thought a diesel most always operates with excess air (or O2) as the intake has no restrictions. You control the rpms or power with the "throttle" by giving it more fuel in the fuel injection charge rather than more air (like a gas engine). My guess is that this elevation change has nothing to do with starting but it is more temperature related. However Turbo chargers do help diesels at elevation more than at sea level as they can out of excess air at the lower atmospheric pressure and O2 levels under heavy engine load conditions.

Yes, The turbo has the ability to "bootstrap" the power up to the fuel limit setting of the injector governor. The turbo just spins a little faster to shove in more of the thinner air.
 

Snobdds

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Diesel throttle controls fuel. Air is never restricted.
Yes that is true, there is no throttle plate in a diesel.

However, throttle is a function of rpm on a diesel and rpm has a air component.
 

SPYDERLK

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Yes that is true, there is no throttle plate in a diesel.

However, throttle is a function of rpm on a diesel and rpm has a air component.
And it is all dependent on the burning of fuel. Air volume per revolution is the same except in turbo equipped engines where boost has developed.
 

Gord Baker

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Carlisle Ontario
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Some Kubotas have indicators to tell you when sufficient Glow Plug time has elapsed. 10 sec seems short.
Try 20-25 Secs with more than idle Throttle setting.
 

stephenh

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Nov 28, 2019
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Rocky Mntns, CO
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kubota L4701
I live at 8500 ft MSL. None of my three Kubortas [normally aspirated] has had any problems due to the elevation. It does get cold here at times, and sometimes I've had to run the glow plug several cycles before the engine fuel would fire off. My previous two tractors had the type of glow plug control I had to hold "on" and the new one determines how long to preheat then shuts off. However, if I cycle the key, it will go through the same timed cycle again. I have had to do this as many as four times in below-zero weather.
 

manzer7

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Aug 27, 2012
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Frenchville, Maine
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John Deere 1025R
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.
I have a JD 1025R with over 600 hours and it starts fine in the summer with the preheater used once and the fuel/air at about halfway. I'm at 750' above sea level. In the winter when it gets to -10 to -30 below I use the preheater 3 or 4 times and it starts fine. I have not had any starting problems until I learned to give it more fuel/air and more preheat times. When I don't use the tractor for a while I put a battery maintainer on to keep it ready to start. I have a 54" snowblower and a ballast box on the 3 point hitch to balance the load.
 
 
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