John Deere 445 constant miss.

[ADRobinson]

My John Deere 445 garden tractor runs great except for a momentary miss that occurs about every 3 seconds. This happens when the tractor is just sitting and while it is moving but it does NOT happen when the PTO is engaged. The PTO drives a 60" mid-mount mower deck. The Kawasaki twin cylinder engine has 1450 hours on it and this problem with the miss has been going on for a couple of years. The valves are properly adjusted and I have replaced the spark plugs, the plug caps, the coil packs and fuel filter and I have used several cans of BG44K injector cleaner. None of this has made any detectable difference. Because the engine runs fine when under a load I can live with the problem but this is really irritating. Can anyone shed any light on how I might resolve this issue?

 

[beenthere]

Ethanol in gas?

Welcome to TBN

 

[jaxs]

Ethanol in gas?

Welcome to TBN

And consequently water in gas?

 

[ADRobinson]

Ethanol in gas?

Welcome to TBN

I have never used ethanol fuel.

 

[ADRobinson]

And consequently water in gas?

No water in the gas. The tank has been flushed since the problem started.

 

[oldnslo]

Real long shot but is this one of the Kawaski engines with the plastic timing gears and is one of the gears starting to go allowing timing to randomly slip while at idle? At full throttle it might have enough inertia to keep everything in time?

I know of 3 different 445s that have had the gears fail but I do not know exact symptoms before they failed.

 

[ADRobinson]

I hadn't thought of that but I do know that my tractors engine has the steel camshaft gear. Thanks for the reply.