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Discussion Starter · #1 ·
Jere39, can you take a video of your mower next time you are out. One I would like to see, is a cold start at about 1/3 throttle, and the other is reduce the throttle from full to low pretty fast. I am just curious if these machines are meant to be throttled down slowly?

Thanks for the helping if you can!

Jon
 

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I think so, when I drop mine down faster, it seems to hesitate, almost hunt a little then smooths right out.

Adam
 

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Have Dog - Will Travel
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I should be able to do that tomorrow easily enough. It's raining here, and cold and miserable. Probably still be cold tomorrow. So I'll do that and post it.

For tonight, I suppose you've already seen these two:

Slowly stepping throttle up and down:
http://youtu.be/PF0tsEVxrwg

Starting from cold on idle:
http://youtu.be/8ChWDWHYYew (I did this on request of someone who specifically wanted to look at auto throttle adjust.)

I'll start at ⅓, then do the quick throttle down. Would you prefer the throttle down on cold engine, or warm engine?
 

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if I reduce from wide-open throttle to low idle fast, my X728 RPM's will surge up and down.
 

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Discussion Starter · #5 ·
Jere, those pretty much answer my questions. I think I need to re-adjust the valves after the dealer has had it, or I may need to check them. A wide open to low idle quick video would be nice.

Thanks all!

Jon
 

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If my X720 does this, I never notice, but will listen for it next time.
 

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My X585 hesitates like that too when decreasing the throttle.
 

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On my old X585SE if I slowed the engine down slowly it was fine. If I was in a hurry it would hunt for a few seconds before settling down and idling right. slkpk
 

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3K & Yet So Little to Say
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I'll throw my hat in too, my X728 did the same thing as the others speak of, a little hesitation on that quick throttle down adjustment.
 

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When I had my X728 I was concerned about this too. I did have a surging problem when the engine idled that did require a small adjustment from the dealer but I still did not like how the engine reacted to sudden throttle changes. I am no expert so these are just my thoughts but after looking thru the Kawasaki engine manual I came to the opinion that this is perfectly normal with the fuel injected gasoline engines in the X700s.

This system is not as advanced as like an automotive system.
It does not have oxygen sensor feedback and relies on preset fuel maps, temp, engine speed, and a MAP system (vacuum to help determine engine load)
It does have a very simple self diagnosis system with fault codes.
It does rely on a governor setup which is kinda mixing the old with the new.
I believe that is where the surging comes into play when suddenly changing the throttle. Many automotive systems use some sort of throttle position sensor. That is crucial in that setup for safety reasons as throttle is often directly related to ground speed. In this setup with driving a hydro system quick throttle adjustment is not as important just as long as the engine does not die from the change. So the electronic fuel injection system has to make changes per it's parameters as fast as it can with no throttle position input. It must wait till the governor/throttle determines a stable engine speed before it can adjust the system for the correct injected fuel needed to stabilize the engine. So since the mechanical governor must play against the fuel injection there is a slight lag time till both balance at a happy medium.

That is my understanding of the system. It is my simple overview as I understand how it behaves. :trink40:
 

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Have Dog - Will Travel
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Cold Start & Throttle Response on x728

This morning in my still dimly lit garage I made a short video as follows:

Cold start on a 38° Morning and Throttle Response
· Setting throttle to 1/3
· Turn key to on, let fuel system pressurize
· Start Tractor
· Let tractor engine settle for 10 seconds
· Gradually throttle up to full
· Dump throttle to low quickly


http://youtu.be/37IV7cEGIGA

Sorry about the lighting, but I think you are mostly listening anyway. I made no comentary while recording so you can hear all the sounds the tractor makes:
· Sticking throttle lever at first
· Return spring on brake
· Electronics and fuel system
· Starter system
· And of course, the engine

When I dump the throttle there is a momentary seek, then settle. Is that what many of you are reporting. Certainly not hunting or surging "for a few seconds", but there is a very brief surge. I've been under the impression that was an emissions thing to burn off excess fuel during decelleration.

Let me know if you need better light, I can push it out in the sun and reshoot

Just some facts:
· 2010 John Deere x728 placed in service November 2009
· 160+ hours
 

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Re: Cold Start & Throttle Response on x728

This morning in my still dimly lit garage I made a short video as follows:

Cold start on a 38° Morning and Throttle Response
· Setting throttle to 1/3
· Turn key to on, let fuel system pressurize
· Start Tractor
· Let tractor engine settle for 10 seconds
· Gradually throttle up to full
· Dump throttle to low quickly


http://youtu.be/37IV7cEGIGA

Sorry about the lighting, but I think you are mostly listening anyway. I made no comentary while recording so you can hear all the sounds the tractor makes:
· Sticking throttle lever at first
· Return spring on brake
· Electronics and fuel system
· Starter system
· And of course, the engine

When I dump the throttle there is a momentary seek, then settle. Is that what many of you are reporting. Certainly not hunting or surging "for a few seconds", but there is a very brief surge. I've been under the impression that was an emissions thing to burn off excess fuel during decelleration.

Let me know if you need better light, I can push it out in the sun and reshoot

Just some facts:
· 2010 John Deere x728 placed in service November 2009
· 160+ hours
Jere39; Did you ever finish that brick dog kennel??Pics
 

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Have Dog - Will Travel
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Re: Cold Start & Throttle Response on x728

Jere39; Did you ever finish that brick dog kennel??Pics
I did, and I hope I didn't mislead anyone. Only the base is brick, I have a 10'x10'x6' fence that lifts off for ease of cleaning (and ease of dropping the 100+ year old oak seen in the corner of these photos but it unfortunately died last year). As usual, I took plenty of pictures when I built it, and If there is interest I can whip them into a quick photo journal on one of the other threads (Sheds ...). I'll include another construction picture with a green tractor in it so as not to depart too far from the thread focus here.

Rearranging the dirt:


Picture from last summer, see that green stuff, before the box I built had completed a remodeling. And before the oak tree was taken down:




Spoiled, but not yet rotten:
 

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Came out very nice,when you push dirt do you lock the plow? I will be using my plow when the weather gets nice..
 

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Discussion Starter · #18 ·
Well, I found the issue with dumping the throttle and getting the reaction that I did. I will post a pic of how everyone can adjust there throttle body to stop that reaction. Very easy to do and works perfectly.

Jon
 

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Have Dog - Will Travel
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Came out very nice,when you push dirt do you lock the plow? I will be using my plow when the weather gets nice..
I don't. I'd rather the springs absorb the jolt of a root or rock than the tractor and operator.
 

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Thanks Jere39, nice to know my tiller already found some cement and plywood pieces in the ground..
 
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