Elevation = rough start up..?

   #1  

Gnome

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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.
 
   #2  

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

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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˙....
 
   #4  

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.
 
   #5  

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).
 
   #6  

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.
 
   #7  

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.
 
   #8  

LS Tractor Owner

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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.
 
   #9  

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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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
 

TMGT

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Yeah give it more throttle. That’ll help resolve it.…
It actually does help as it is more efficient at higher rpm/fuel setting, since it already has a higher fuel to air ratio due to the lower atmospheric pressure it can help smooth it out.
 

Hay Dude

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It actually does help as it is more efficient at higher rpm/fuel setting, since it already has a higher fuel to air ratio due to the lower atmospheric pressure it can help smooth it out.
I know, that’s why I supported the suggestion!
 

the old grind

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Yeah, diesels have to have the right fuel/air mixture at any rpm. Just give it a little more choke. ;)
 

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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.
Also a MT owner but at 1500 ft.
In winter I always need a block heater for 1 hour and often cycle the glow plugs twice.
Heck even in summer I need glow plugs, just the nature of the beast.
 

sea2summit

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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
Ummmm, pretty sure that's not how math works to get a percentage.

"Air" is also a dangerous assumption. "Air" doesn't cause ignition it's the O2 in the air.

For partial pressure O2 at sea level it's ~20.9 at ~14.7PSI, going to 3,200' it's just less than ~2 PSI lost (about 1.8), so (1.8PSI/14.7PSI)*20.9 PPO2=~2.55PPO2.

So loosing ~2.55PPO2 from sea level that's ~2.55PPO2/20.9PPO2= 12.2% loss of O2 per volume.

Carry on.
 

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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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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.
 

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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.
 

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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.

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.
 

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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.
 

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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.
 

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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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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.
 

priberc

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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.
Might wanna put some thiner oil in it....5w/40 instead of the summer weight oil that is in it. That may help it start easier. But cold engines all run rough for a time when starting cold/not plugged in
 

jyoutz

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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 live at 6850 elevation and I’ve never had to have any altitude adjustments.
 

jyoutz

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Might wanna put some thiner oil in it....5w/40 instead of the summer weight oil that is in it. That may help it start easier. But cold engines all run rough for a time when starting cold/not plugged in
In my truck with Cummins diesel, I used to have to plug in the block heater overnight when temps fall below 10 degrees. After switching to Rotella T6 synthetic oil, I haven’t yet had to use the block heater to start the truck.
 

ForestGrump

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I live at 7,000‘ and are lows are in the 20’s, now. Longer use of the glow plugs gives a smoother startup as does a little throttle. Once it starts increase throttle till the engine smooths out. Usually she does smoke at startup. I use Shell synthetic Rotella 10—40 And California ultra low diesel.
 

piper184

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It seems that every diesel engine has its own little idiosyncrasies particularly when it comes to starting. My tractor for example needs a little glow plug help even up to about +70 degrees, at least on the first start of the day. I usually start at about 1/4 throttle and then idle down to 1000 RPM for warm up as soon as all cylinders are firing evenly. After 14 years I can just about guess what will be needed for a smooth start at any temperature. Experience is a great teacher.
Cold engines generally require a richer mixture for cold starts. You elevation change actually helps that. However cold air is more dense so you have to compensate for that with more fuel. It is entirely possible to "flood" a cold engine. Cranking for a few seconds with the fuel in cut off (if possible) will help in these situations.
Make sure your glow plugs are actually all functioning. Having a dead one or two will really take a toll (ask me how I know) Also battery condition plays a big part as well as starter condition. Mine needs to be cleaned and lubed every few years to keep it in tip top shape. Even more important as temps drop.
Fuel grade may play a part too, although I don't know if that will affect ignitability. Shouldn't be an issue at your current temps but if you plan on using at lower temps you might want to check into that as well as have some anti-gel additive on hand.
 

DSteiner

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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).
Diesels do not throttle the air like a gas engine. There should be no noticeable difference between the two altitudes.
 

CoyPatton

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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.
Sorry to burst your bubble, but air is regulated on all engines. I know I am old, but even old gas burners using carbs had butterflies that somewhat controlled air mixture with fuel. Modern gas burners are fuel injected so mixture happens in the cylinder much like diesel engines. However the air is still regulated. There are lots of electronic things present on fuel injected gas burners measuring and regulating air mixture. Just thrown a few MASS air flow, IAC, TPS, the list continues.
 

jayhawk238

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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 live in Idaho at 4500 foot and have no problem with my Kubota L5030 in the winter. However, I do have a block heater and a battery blanket installed. Helps in a huge way!
 

CobyRupert

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We sure engine isn’t getting a burp of bad fuel? Temps are getting colder, wide night-day cooling swings. If there’s a low fuel tank level that’s mostly air, it can pick up a few drops (or more) of condensation with cooling cycles and water settles to bottom of tank where effects are experienced for the first minute or so at start up.
 

the old grind

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I agree that diesels are easy to flood above sea level and suggest an under-recognized cause is a sticky butterfly in the intake tract. Throttle position sensor or someone haveing tinkered with idle mixture screws can also impair a proper stoichiometric air/fuel ratio & glow plugs might not fire below 1/4 throttle.

btw, beware of a lean run condition caused by a plugged tank vent that doesn't allow equalization between that and the fuel bowl vent in the injector pump.

Things really haven't changed that much since the old days. ;)
 

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Diesels do not throttle the air like a gas engine. There should be no noticeable difference between the two altitudes.

You have to run more RPM at altitude for the same power...
 

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Anybody here know anything about diesels at altitude, and with and w/o turbo speak up please.
 

the old grind

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Just like how a turbo gives more power without more fuel, or how diesels make so much more smoke at altitude for lack of air.

(not to get technical, but I was just warming up... :sneaky:)
 
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puzlrock

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When it gets cold in Montana I plug in the tank heater, starts and runs great.
 

DutchInNZ

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Ummmm, pretty sure that's not how math works to get a percentage.

"Air" is also a dangerous assumption. "Air" doesn't cause ignition it's the O2 in the air.

For partial pressure O2 at sea level it's ~20.9 at ~14.7PSI, going to 3,200' it's just less than ~2 PSI lost (about 1.8), so (1.8PSI/14.7PSI)*20.9 PPO2=~2.55PPO2.

So loosing ~2.55PPO2 from sea level that's ~2.55PPO2/20.9PPO2= 12.2% loss of O2 per volume.

Carry on.
etpm is right; that is the diesel physics. A diesel gets to its ignition temperature by adiabatic compression of air to bring it to a high temperature, after which fuel is injected that then burns with the oxygen. Less air in = lower compression = lower temperature, so no ignition or bad irregular burning, which makes the typical diesel knocking sound until the engine is warm.
 
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DutchInNZ

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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.
Less air pressure in equals less volume of air in equals less pressure at TDP equals lower adiabatic ignition temperature equals bad starting when cold.

My Zetor, as all of the old series, does not have glow plugs but a very high compression ratio that makes for problem-less starting.
 

SPYDERLK

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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˙....
It is to be expected with the thinner air and consequently lower compression heat. There will also be a slight?probably unnoticeable loss of power even when warmed because each lungful is a little less air than at sea level. At full load there is more likely to be an excess fuel condition - exceeding the amt burnable in the slightly air starved condition.

A turbo equipped engine will see the same startup issue, but then will pretty quickly come up to a wholly undiminished power capability as the cylinders warm and exhaust heat and boost develops.
 

JasperFrank

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Interesting reading glow plug times of more than 5 seconds. 15 Seconds? Sat with my stop watch and timed out 15 seconds. I have never held the glow plugs on for more than 5 seconds. 1200 feet, very small 1 liter engine and garage rarely gets below freezing. Wonder if excessive use of glow plugs is in anyway harmful to the engine? What are the recommended glow plug times for larger tractors?
 

SPYDERLK

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Interesting reading glow plug times of more than 5 seconds. 15 Seconds? Sat with my stop watch and timed out 15 seconds. I have never held the glow plugs on for more than 5 seconds. 1200 feet, very small 1 liter engine and garage rarely gets below freezing. Wonder if excessive use of glow plugs is in anyway harmful to the engine? What are the recommended glow plug times for larger tractors?

Only harmful to the glowplug.
 
 
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