JD 6220 SE decelerates all the time

[mkymus]

Hi all
I have a John Deere 6220 SE when I start it it runs for about 5 minutes then Decelerates. I have checked the fuel there is no water in the system and the senses are fine.
I have changed the oil transmission cleaned all the filters and it still does the same thing.
There is a red flashing light that flashes on and off once the tractor warms up.
I have changed the radiator coolent a tad overdue ( I didn't relise there was a time limit when it should be done) that made a little bit of difference but it is still doing the same thing.
There are three senses on the water cooling system. Could they be the problem due to the lack of maintance?
I have had our local JD mechanic come and look at it. They have not been able to fix it and every time they come out 3 times so far, it more cost.
It would be nice if I could get hold of a diagnistic disc and computer cable that I could check the whole system. Thanks
Does anyone have a suggestions please.
Thanks for taking the time to read this.

 

[PhilY]

I've never had an issue like this before, but here's a few things that might help you along. First thoughts would be fuel delivery or compression. If it's about 5mins after it has started up that it begins to loose engine rpm's, it could be a vacuum in the fuel system due to a clogged vent, or a dirty fuel filter. There should be enough fuel in between the filter and engine to run for 5 mins or so. Also, this is about the time the engine is well on its way to being warmed up. Most of the time I would think that any leak present in a gasket on the engine would seal itself after up to temp, but if a bolts not tight or something got warped, I could see something like this happening. On my 2500HD, I had a few bolt heads on the exhaust manifold pop off. This isn't uncommon on these trucks unfortunately, but what they said is that GM uses a bolt that stretches to keep uniform tension on the manifold. So at about 120K miles you might see one because they have a limited life. Not sure if this would be true of all manifold bolts these days.

I would start with the fuel filter though, I'm surprised at the crud in there sometimes with the fact that all my fuel comes from the gas station.

 

[mkymus]

When the JD mechanic came out he said the same thing. All fuel lines have been checked there no leaks and the fuel sensors are all working Ok. The filters are all brand new.

 

[PhilY]

You mentioned that the coolant change made a little bit of a difference. This might mean that with the new coolant it just took the engine a little longer to warm up and the problem to show itself. How much would you say the engine rpm's drop? Is this noticed at any throttle position or just in idle? Also, how many hours do you think you have on the engine? Valves sometimes don't seat completely after a while, but with valves this would probably be an issue whether or not the engine was warmed up. All I can think of at this point is either intake or exhaust manifold gasket, valves, or maybe a bad glow plug (but I don't think a GP could work and then not maintain temp).

 

[mkymus]

PhilY I will have to get back to you on your question as it is 2:00am this way I will go check in the morning.
I was wondering if the sensor in the top radiator tank was crook would that make the computer think it was low on coolant and shut it down?

 

[mkymus]

Hi PhilY
The tractor was 2004 built. Has done 1062 Hrs. and deaccelerates electronically from the computer any throttle settings gradually goes back to idle. If I move the throttle from idle to full throttle the back to idle it then runs at a lower rev settings.
I tend to think it may well be a computer problem.
The fuel tank has been cleaned and the pick up strainer and hose to the fuel pump has been replaced.
The Transmission oil was changed a couple of days ago with the two filters changed and the pickup strainer cleaned.
There is no glo plug on this model. I have also checked all the wiring for both mouse and rats chewing on the cables and there is no sign of that either.
I hope I have all what you wanted thanks

 

[Zebrafive]

It does sound like the computer is lowering the power level. It must be getting an input telling it there is a problem, so it lowers the rpm. Dealer should know which sensors to check.

 

[mkymus]

well we have had the dealer's mechanic out 3 times so far and either he has no idea what he's doing because originally he said it was the fuel sensors so checked them all changed the filters still did the same thing. Next time he came out said it was the transmission so again replaced the oil and cleaned one filter and replaced the other two, Still doing the same thing, as i posted earlier even changed the coolent the only thing I haven't done is check thesensor on the top of the radiator top tank to see if it is coroded,
that's why I put my comment in for a diagnostic disc and the computer cable to go with it and I would have a go myself.
Everytime the mechanic comes out expects to be paid but still hasn't fixed the problem,
I would like to get hold of a wiring diagram for the 6220 SE. as the mechanic said to water sensors are on a different circut and I would like to check that for myself. Thanks

 

[PhilY]

I believe you might be on the right path with it being a computer/sensor problem. If the engine sounds like it is running smoothly like it always has when in idle. I would probably say its the computer throttling the engine down for some reason. I know there is a website called messicks that has some diagrams for wiring.

Messick's | Dealer for New Holland, Case IH, Kubota, Cub Cadet and More | Online Parts, Sales & Service.

If you're local tech has been out a few times with no success, I might call Deere up and see who there local area rep is. They may be able to help you out to diagnose the computer.

 

[mkymus]

Thanks PhilY
Where I live we have what we call the Elmore field days I was planning on going there and see if I can't get a senior service rep out rather than a junoir.