Jerky throttle

[North Idaho Wolfman]

Yeah I tried everything. Makes no difference when the machine is at full running temperature. So weird


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If the engine RPMS are surging when when you turn off the auto throttle, your problem probably has nothing to do with controls, but the actual delivery of the fuel to the system, like a plugged /contaminated fuel, filter, line, or tank, or possibly a bad fuel pump.

 

[Kubotasidewalkdude]

If the engine RPMS are surging when when you turn off the auto throttle, your problem probably has nothing to do with controls, but the actual dilivery of the fuel to the system, Like a plugged /contaminated filter, line, or tank, or possibly a bad fuel pump.

They aren’t surging when I turn the auto throttle off


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[North Idaho Wolfman]

Please go back and read what people ask, because your answers are all over the board!
When asked questions you never give a complete answer.

Backing up all the way to your first post:

In the beginning you stated that it had an issue with it still traveling when you let off the pedal, and that the engine rpm's surge.

If it doesn't surge when the auto throttle is off, you have a HST control issue, like others have said, water / salt in switches, connections, and wiring will cause all of the issues you are trying to explain, tractor warms up, water melts causes bad / faulty connection.

 

[Kubotasidewalkdude]

Please go back and read what people ask, because your answers are all over the board!

When asked questions you never give a complete answer.



Backing up all the way to your first post:



In the beginning you stated that it had an issue with it still traveling when you let off the pedal, and that the engine rpm's surge.



If it doesn't surge when the auto throttle is off, you have a HST control issue, like others have said, water / salt in switches, connections, and wiring will cause all of the issues you are trying to explain, tractor warms up, water melts causes bad / faulty connection.

I just reply to questions as best I can dude lol. The issue at first was the tractor driving on its own and rpms surging but now it doesn’t drive on its own and the rpms surge after it fully warms up. It’s just been confusing to try and see what’s happening, especially since it’s been -30 almost every night for the past week.


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[Kubotasidewalkdude]

Alright guys. It’s been a while but here’s an update. Our mechanic said he dealt with someone who had a similar issue. He told me this guy went into the settings of the tractor on the dash and was able to recalibrate it. Has anybody heard of this before I go online?


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[North Idaho Wolfman]

The fact that you had creep and then a surging motor leads me to the auto throttle linkage binding up.
This would cause both issues.
I doubt very seriously that its a programming issue.

 

[conropl]

From the panel, you can:
- Adjust the HST sensitivity (more jerky or smother)
- Turn on/off Auto-Throttle
- Adjust the Max RPM for the Auto-Throttle.
- Turn on/off Auto- H-DS (automatically shifts the H-DS lever from high to low or low to high) which can make it quite jerky and cause it to surge. (H-DS is the high low selector for each H-M-L range - essentially giving you 6 total ranges).
- Turn on/off the stall guard (slows tractor ground speed based on load).
- Turn on/off or set the max RPM for the Throttle-Up switch on your FEL control lever.

Personally, I did not like Auto H-DS because it does get quite jerky and causes an unexpected surge (especially at full throttle). So I turned it off. That can explain some of what you describe, but I am not sure it explains it all. But you need to turn that feature off before you can get to the bottom of any other issue that may be going on.

Also, make sure you are not bumping the throttle up button on your FEL control lever - that could cause some surging. Easy to do with thick gloves on. In fact, turn it off until you figure out what is going on.

 

[North Idaho Wolfman]

Does the L3940 (mechanical fuel injection) have the same control over the engine as the L3560 (electronic fuel injection)?

 

[conropl]

Does the L3940 (mechanical fuel injection) have the same control over the engine as the L3560 (electronic fuel injection)?

I am sorry... I remembered wrong. I was thinking he had a L3560. Don't know where I got that from.

But the Grand L 40 series still had the Auto H-DS, Auto-Throttle, HST Sensitivity dial, and Stall Guard. But I do not think it has the Throttle up button (I may be wrong on that though). All of the above should be turned off to see how much (or if) they are contributing.

Look under "HST Plus" heading under this link.

http://www.orangetractortalks.com/2010/10/an-overview-of-kubotas-grand-l40-series/

 

[Kubotasidewalkdude]

From the panel, you can:

- Adjust the HST sensitivity (more jerky or smother)

- Turn on/off Auto-Throttle

- Adjust the Max RPM for the Auto-Throttle.

- Turn on/off Auto- H-DS (automatically shifts the H-DS lever from high to low or low to high) which can make it quite jerky and cause it to surge. (H-DS is the high low selector for each H-M-L range - essentially giving you 6 total ranges).

- Turn on/off the stall guard (slows tractor ground speed based on load).

- Turn on/off or set the max RPM for the Throttle-Up switch on your FEL control lever.



Personally, I did not like Auto H-DS because it does get quite jerky and causes an unexpected surge (especially at full throttle). So I turned it off. That can explain some of what you describe, but I am not sure it explains it all. But you need to turn that feature off before you can get to the bottom of any other issue that may be going on.



Also, make sure you are not bumping the throttle up button on your FEL control lever - that could cause some surging. Easy to do with thick gloves on. In fact, turn it off until you figure out what is going on.

The only time I use the throttle lever is when I’m pushing a good amount of snow. I drive with auto throttle advance on, stall guard on and usually in H unless I’m driving on grass and I throw it in M. I’ve tried different combinations of settings and nothing seems to work. But what I asked was, how can I get into the settings and set the pedal and RPM calibrations? My guy said you basically drive back and forth at different speeds and it goes through a bunch of different steps to set the rpms and speed or something...


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[conropl]

The only time I use the throttle lever is when I’m pushing a good amount of snow. I drive with auto throttle advance on, stall guard on and usually in H unless I’m driving on grass and I throw it in M. I’ve tried different combinations of settings and nothing seems to work. But what I asked was, how can I get into the settings and set the pedal and RPM calibrations? My guy said you basically drive back and forth at different speeds and it goes through a bunch of different steps to set the rpms and speed or something...


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Don't know how to help you there. As for setting the sensitivity for the HST peddle, there is an adjustment knob on your dash for that... but I would assumes you already tried that.

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[Kubotasidewalkdude]

Don't know how to help you there. As for setting the sensitivity for the HST peddle, there is an adjustment knob on your dash for that... but I would assumes you already tried that.

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You mean the throttle lever on the right or the adjustment knob on the left?


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[coachgeo]

You mean the throttle lever on the right or the adjustment knob on the left?....

might find some info you need at

at 8 min mark here is my guess a similar knob on another model being refereed too. https://www.youtube.com/watch?v=Hf3VGcGg8fU


More info

http://www.messicks.com/blog/post/proper-operation-of-the-kubota-hst2b-transmis.aspx

https://www.youtube.com/watch?v=m5ACaNF3fvg

 

[BAP]

Best place to start is to learn how to read your owners manual for your tractor. It should explain all the controls and how to use them

 

[conropl]

You mean the throttle lever on the right or the adjustment knob on the left?


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I believe it is the knob on the left that adjusts the HST sensitivity. But as others have said, the owners manual is the best bet because auto H-DS would be a worse problem. It is not the same as auto throttle, and it can cause you to be shifting from hi to low (turtle and rabbit) automatically... which can be kind of jerky (I do not like it at all), and with auto throttle it is worse. I cannot tell you how to make those changes on your machine (mine is a little different), but the manual can.

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[Kubotasidewalkdude]

I believe it is the knob on the left that adjusts the HST sensitivity. But as others have said, the owners manual is the best bet because auto H-DS would be a worse problem. It is not the same as auto throttle, and it can cause you to be shifting from hi to low (turtle and rabbit) automatically... which can be kind of jerky (I do not like it at all), and with auto throttle it is worse. I cannot tell you how to make those changes on your machine (mine is a little different), but the manual can.

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It doesn’t shift from turtle to rabbit lol. I’ve played around with the HST knob and ha e never found a difference whether I turn it up or down...


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[Kubotasidewalkdude]

Finally said screw it and brought the L3940 to kubota. As soon as I got there I had no forward and reverse. Guy says it’s most likely the HST valves and they are $1000 each lol. I hope it’s something else when he tears it apart


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[Kubotasidewalkdude]

Not sure if anyone is still following this post but it turns out the HST valves seized up. The original quote was for $1000 per valve but I think those are for a bigger tractor. Bill came to about $600 for the two valves and bolts and another $600 in labour...


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[conropl]

Good to hear you got it fixed.
Thanks for the update... I was curious.