I have a 4720 and when the ambient temperature is cooler, not exactly sure at what temperature, even though the engine is warm , when you start it the engine goes to fast idle for a while then slowly idles down..does anyone know how to stop this from happening? There must be a temperature sensor somewhere that can be bypassed or possibly moved to another location that may sense a higher temperature? It痴 quite annoying and uses more fuel than necessary.. thanks
4720 fast idle
- Thread starter birchbark
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kennyd
Advertiser
Normal...don't second guess engineers.
Beaver Cove Deere
Gold Member
Annoying? Absolutely, but I'm not sure tinkering with the onboard computer is worth the potential hassle.
I had two bosses that would have kicked me to the curb running an ice cold diesel at 1500RPM's during start up or within the first 5 minutes.
Yes I get it but totally unnecessary.. I was hoping someone might know where the sensor is located .. I would move it or jumper it somehow. I worked with sensors and thermistors for 30 years so very capable if I could find its location.. there has to be a sensor somewhere that measures ambient temperature
ptsg
Super Member
Probably there is a sensor but that sensor may also send signal to the glow plug timer so it adjusts the time the glow plug turns on accordingly to the coolant temp.
dadiehl
Silver Member
My JD 3320 did it. I never had so much as one problem with that machine. Sold it with 600 hours. My Kubota M7060 does it. I just assume god intended it this way. If it’s really cold I run my bullet under the machine for about 45 minutes in the shed. After that it does not do it when I start it.
jenkinsph
Super Star Member
As I remember reading that the low idle speed is more damaging causes more vibration than the fast idle. Also less likely to build up internal deposits and faster warm up. I am not an engineer but I notice that most engines today have this same feature. Must be a common agreement that it is worthwhile. I agree with others to leave it alone and enjoy your tractor.
RoyJackson
Rest in Peace
- Joined
- Nov 17, 2001
- Messages
- 23,144
- Location
- Bethel, Vermont
- Tractor
- John Deere 4052R Cab,, Deere 855D UTV, Z920A Zero Turn Mower and assorted implements
I had a 4520, now a 4052R..
Once I start the engine and oil pressure is normal, I always increase RPM to 1500 or so.
Diesel at slow idle don't heat up and wet stacking can result.
The 4052 is my 5th Deere...I've followed the same starting procedure on all of them
Once I start the engine and oil pressure is normal, I always increase RPM to 1500 or so.
Diesel at slow idle don't heat up and wet stacking can result.
The 4052 is my 5th Deere...I've followed the same starting procedure on all of them
Last edited:
Bavarian
Platinum Member
The bigger tractors do the same. They usually use coolant temperature for glow plug and high idle.
IIRC, the manual says, once the engine speed drops down to normal RPM, it's ready to go. And that's long before any temp would show on the gauge.
And I still don't rev it up past 1700 during the first few minutes after that.
IIRC, the manual says, once the engine speed drops down to normal RPM, it's ready to go. And that's long before any temp would show on the gauge.
And I still don't rev it up past 1700 during the first few minutes after that.
