2012 John Deere Gator 850i RSX Idle Problem

[N00bie]

From Arkansas. Just bought a 2012 Gator 850i RSX because I could not pass up the price. BUT it has an idle problem. So, to be honest, I joined just to get a service manual. I have a choice: 1)Buy a hard copy: ~$100; 2)Buy a CD ~$35.00; Get a direct download for free posting 10 times; or get a download for $29.00 (subscription). Haven't decided what to do yet.

[Admin]

We have the 2014 posted (not sure if it will fit for 2012). We have the 10 post rule specifically for these reasons because people join for manuals and leave. To stay relevant, sites like these need member participation. So we offer these things to members for free if they participate. $29 subscription here is annual and provides access to the full library downloads and a no ad experience for a year. Just saying, if you don't feel like participating/posting...its an option.

 

[Mech]

Service manuals are out there in the web, free to download. You don't need to join up to anything to get a manual.

This is a good forum though, one of the best.  If you have trouble finding the cause of the idle problem, yell out and we can probably talk you through to the cure... even without a manual.

[N00bie]

I have yet to find a free manual. The TM109919 is for all years so the 2014 would be fine. So again, what are my choices (cant find a freebie):

1. Post a bunch of worthless posts just be be cheap and get the manual for free

2. Buy a manual on eBay for about $30.00 (a CD)

3. Buy a download from some other stranger for $25

4. Donate $29 to you folks.

I think I will choose #4 as I need it now, Maybe you folks will have the parts manual too and make it double worth while.

[N00bie]

OK, now that we are through all the BS and I simply purchased the service manual, let me tell you the problem with the machine while I dig into the manual...

The engine starts fine but does not idle. You have to keep pumping the throttle to keep it alive. You can go fast down the road and she goes, but idle no. It did have a bad 02 sensor but fixing that had no effect. In fact, unplugging the 02 sensor does not make a difference. Have not unplugged both - will do that tomorrow. The problem with the 850i is that all your sensors are in the throttle body and are not serviceable (and it is not a  cheapo piece). Will probably have to start ripping the engine apart?

[Ajmboy]

My guess is that its at the throttle body and something with the idle air control. Some have separate IAC motors, this looks like its all part of unit. 

I would also check for vacuum leaks.

[N00bie]

That is the problem with this machine. Everything is in the throttle body ($1,200+).
Haven't found a vacuum leak.

[Ajmboy]

14 minutes ago, N00bie said:

That is the problem with this machine. Everything is in the throttle body ($1,200+).
Haven't found a vacuum leak.

Do you have a smoke machine? If not, I would get a cheap one and search for vacuum leaks around the intake.

I have one from amazon I use on my cars and stuff like this, works pretty good with baby oil.

Amazon Link

[Mech]

It's likely that the O2 sensor wasn't defective. It quite likely was just struggling to control the mixture within acceptable limits and so reported it as not working. That's quite common with O2 sensors. They are one of the most miss-diagnosed components.

I'd be checking the throttle cable adjustment, the fuel flow and pressure, the IAC operation(might operate on 5volts so be careful), and the spark plug gap and condition.

[quadmaniac]

With fuel injection, it’s like a car… I would take the throttle body off and inspect. Maybe get some throttle body cleaner and spray it first and see what that does. 
 

[N00bie]

10 hours ago, Ajmboy said:

Do you have a smoke machine? If not, I would get a cheap one and search for vacuum leaks around the intake.

I have one from amazon I use on my cars and stuff like this, works pretty good with baby oil.

Amazon Link

Nothing beats a cigarette, Wish I still smoked

6 hours ago, Mech said:

It's likely that the O2 sensor wasn't defective. It quite likely was just struggling to control the mixture within acceptable limits and so reported it as not working. That's quite common with O2 sensors. They are one of the most miss-diagnosed components.

I'd be checking the throttle cable adjustment, the fuel flow and pressure, the IAC operation(might operate on 5volts so be careful), and the spark plug gap and condition.

The 02 sensor was bad (threads were stripped and it fit loosely in the housing but wasn't the real problem. Can disconnect both 02 sensors and no change. Throttle cable not really adjustable and IAC is integral to the throttle body and not serviceable.

[N00bie]

3 hours ago, quadmaniac said:

With fuel injection, it’s like a car… I would take the throttle body off and inspect. Maybe get some throttle body cleaner and spray it first and see what that does. 
 

Not much to the throttle body that you can access. There are only 2 little holes where are the good stuff is located that cannot be serviced. Just pulled out the entire throttle body and cleaned it (wasn't really dirty) but don't expect it to do much.

 

[Mech]

The throttle cable is sure to have some adjustment somewhere. Polaris bikes have a kill switch built into the throttle and if there is slack in the cable, such as you would get if the throttle stuck on and your thumb was off the pedal, then it kills the engine. If those get too much free play in the cable at idle they kill the engine. It wouldn't surprise me if JD did the same. Apart from that though, if the throttle is held too far open, by the cable or someone having adjusted some stop somewhere, then the idle control motor or valve can't compensate enough and keeps the idle speed wound right down to zilch as much as it can, and that sets off a cycle of compensations and counter compensations that often ends in an engine not idling.

I don't have the book, but I'd bet it says to check those things, and do a standard sort of tune and inspection of hoses etc.

[N00bie]

You can adjust the throttle in the throttle body but would have to set it to about 4,000 rpm to keep the motor running. Low idle is entirely different than erratic idle (up down, up down -> dead)

[N00bie]

Gator idling (or trying to)

Edited April 15 by N00bie

[N00bie]

After going through the entire service manual with the same issue and no solution. Manual stops at "service ADVISOR". So, will probably need to get a jar of Vaseline and go to the John Deere dealer.