John Deere Gator Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
I’ve got a 625i that recently started missing when you first start it up. That goes away but it has engine knock at a certain rpm. It’s fine when your running full throttle. I’ve tried sea foam, changing spark plugs and fuel filter
 

·
Registered
Joined
·
31 Posts
My 825i had a miss and a knock. Not sure how rpms affected it, as I bought it that way and didnt run it much. Mine ended up being a bad rod bearing. Hope yours is easier to find and fix. Look for shavings in your oil pan to be sure. How many hours are on the machine?
 

·
Registered
Joined
·
4 Posts
Discussion Starter #3
My 825i had a miss and a knock. Not sure how rpms affected it, as I bought it that way and didnt run it much. Mine ended up being a bad rod bearing. Hope yours is easier to find and fix. Look for shavings in your oil pan to be sure. How many hours are on the machine?
It has 730hrs on it. It sounds more like it’s detonating. It sounds fine if you put it in neutral and rev it up.
 

·
Registered
Joined
·
1,297 Posts
If you suspect more of a detonation issue, perhaps try adding one of the octane boosters or complete fill with premium (93 octane fuel) to see if it subsides.

The miss could be spark related (or lack of). Check the integrity of the spark plug wires and boot very closely. It doesn't take but a pin hole in the insulation for the spark to jump through the wire versus plug... A number of people have experienced bad spark plug wires in the past.

What additional diagnostics have you done since posting?
 
  • Like
Reactions: Bradhill

·
Registered
Joined
·
4 Posts
Discussion Starter #5
If you suspect more of a detonation issue, perhaps try adding one of the octane boosters or complete fill with premium (93 octane fuel) to see if it subsides.

The miss could be spark related (or lack of). Check the integrity of the spark plug wires and boot very closely. It doesn't take but a pin hole in the insulation for the spark to jump through the wire versus plug... A number of people have experienced bad spark plug wires in the past.

What additional diagnostics have you done since posting?
I’m getting plenty of volume from the fuel pump. I’m not sure about pressure. I’ve tried high octane fuel and no difference. I couldn’t see any place where the spark would be grounding out.
 

·
Registered
Joined
·
35 Posts
I’ve got a 625i that recently started missing when you first start it up. That goes away but it has engine knock at a certain rpm. It’s fine when your running full throttle. I’ve tried sea foam, changing spark plugs and fuel filter
Does the knock start showing up as the engine hits operating temp? When it starts to knock what would happen if you eased the choke out a little bit but not so far as to make it blubber? I have no idea about the miss when starting up except to ask if its different with a warm start vs a cold start?
 

·
Super Moderator
Joined
·
3,187 Posts
From the Deere’s mouth...

Engine miss at low rpm..

13745


Engine Knock....

13746
 

·
Registered
Joined
·
35 Posts
Bradhill, the troubleshooting pointers are good. The reason I asked hot vs cold is that if there is a buildup in the combustion chamber it could be an issue. It wouldn't necessarily show on the plug, But my gosh, these engines run really clean. I think the ECU is an expensive but good place to look. But it is hard to test.
 

·
Registered
Joined
·
3 Posts
I’ve got a 625i that recently started missing when you first start it up. That goes away but it has engine knock at a certain rpm. It’s fine when your running full throttle. I’ve tried sea foam, changing spark plugs and fuel filter
I had to replace my ignition coils. Little as $24 apiece. Corrosion got to the + lead on the rear
one. Harder to change of the two.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #11
Thanks guys for the information. I tried replacing the ignition coils since they were inexpensive but still the same problems. I guess I’ll try an ecu next
 
1 - 11 of 11 Posts
Top