Engines not reving up or shutting down coming from auto idle

Hi all,
Just a general question so to speak. I had 4 cases recently where engine auto idle function is active, you activate a command, and if you don't do it gently at first and give engine a second to come back to working RPM it will shut down, or won't be able to rev up, but struggle in low RPM, you then ease off on the joystick, revs come up, and off you go working normally again. Like engine needs more of "something" to rev up. Excavators were:
Litronic 914
Volvo EC360B NLC
Kobelco SK250-8
Takeuchi - forgot what model
By changing air and fuel filters, problem was cured only on Volvo, on others problems remained. Now customers in all 3 remaining cases stated they will stop using auto idle temporarely as they can't spare time to investigate this further, but eventually they will come back to get the problem fixed.
What are your experiences with this sort of a problem?

Do the other 3 have pump, line and nozzle, or common rail or electronic fuel injection? Just looking for a common denominator

No commonrail / electronic on any of them

So the other 3 run off a stepper motor for throttle control?

Well, I could probably help on the takeuchi. Model AND 1st 4 digits of the serial number.

On the kobelco 250 - 8 what is your low idle set to. If its too low it can cause the rpm to be slow to pick up. It might just need to be recalibrated

heymccall said:

Well, I could probably help on the takeuchi. Model AND 1st 4 digits of the serial number.

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I'll have to get back to you on this one. I didn't note down any of the details as I was basically called in as I was passing by, and I was short on time. As service wasn't done on it for a while as they said, I advised to change filters and oil and see from there. They reported back that issue still remains after this.

funwithfuel said:

So the other 3 run off a stepper motor for throttle control?

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Step motor controls.

To be honest, I didn't spend much time investigating problems on any of these 4, as they were all short on time and itchy to keep working, and auto idle wasn't an issue for any of them. I just wanted to get a bit more of general idea what do you guys usually come across to be cause of the problem for these issues. Speaking to some more experienced mechanics, 90% of cases as I was told issue is fuel or air (not so much) supply to the engine.

Kobelco ireland said:

On the kobelco 250 - 8 what is your low idle set to. If its too low it can cause the rpm to be slow to pick up. It might just need to be recalibrated

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Actually guy just called me this morning about some engine overheating issues happening in last few days apparently, so I'll be visiting him in next few days and I'll check the RPM setting.

funwithfuel said:

So the other 3 run off a stepper motor for throttle control?

Click to expand...

My memory is just refreshing now. Takeuchi didn't have stepper motor, and I think it is commonrail system. Sorry, this was few months back and I can't be sure 100%.