GX460 P2714 P0761 Ultimate Summary and Hope For A Fix Thread

[Rednexus]

This gives me hope, and given a lot of things happening in my life right now, I need that. Thank you!

I got the plugs from O'Reilly Auto Parts locally.

I'm going to pull plugs, swap coils around and see what happens.

I also think the coolant leak, unless I find coolant elsewhere, might be the overflow cap.

Swapping the coils around is the thing to do. When I've had misfires it's either been coil related or internal engine damage. If you still get misfires on the same cylinders with swapped coils I'd run a compression test which would help ID a burned valve or other issue causing a misfire (all 8 cylinders, wet and dry).

I have not diagnosed a head gasket leak on a 1UR but I have on Subarus. If you think the engine is burning coolant, you could also drop a borescope/inspection camera down each cylinder and see what the top of the pistons look like. They should be black with carbon....if not, you may have coolant getting in the cylinder and steam-cleaning off the carbon. On the Subaru I diagnosed it had the opposite problem - exhaust gasses were getting into the coolant.

 

[gsi18867]

This gives me hope, and given a lot of things happening in my life right now, I need that. Thank you!

I got the plugs from O'Reilly Auto Parts locally.

I'm going to pull plugs, swap coils around and see what happens.

I also think the coolant leak, unless I find coolant elsewhere, might be the overflow cap.

My overflow cap died last week when I was refilling after transmission reinstall. Plastic crap

 

[Schwooby]

Swapping the coils around is the thing to do. When I've had misfires it's either been coil related or internal engine damage. If you still get misfires on the same cylinders with swapped coils I'd run a compression test which would help ID a burned valve or other issue causing a misfire (all 8 cylinders, wet and dry).

I have not diagnosed a head gasket leak on a 1UR but I have on Subarus. If you think the engine is burning coolant, you could also drop a borescope/inspection camera down each cylinder and see what the top of the pistons look like. They should be black with carbon....if not, you may have coolant getting in the cylinder and steam-cleaning off the carbon. On the Subaru I diagnosed it had the opposite problem - exhaust gasses were getting into the coolant.

This is what I did today:

Pulled the ignition coils on the problem cylinders. Checked the spark plugs and took pics. I didn’t see anything inside the cylinder, but I did see what looked like a little oil on the threads. The coils themselves do look not great. A couple were missing springs. I’m going to order new coils. Swapped coils between 2 and 4 and 7 and 5, started the 460 and let it run for 20 mins or more. Def reached operating temps. No check engine / vsc / 4lo. No codes. I’m going to order new coils anyway.
This is a plug I put in about a month ago.

The following are old and from the problem cylinders.

Also found this:

Which hose is this and what does it do? Is it possible for this to create conditions that would cause a misfire? That connector is disconnected because I had to remove the air filter box and hadn't plugged that sensor back in.

 

[Schwooby]

So that hose is the fuel pressure damper hose.

It can absolutely cause a misfire.

 

[TXMeatball]

Throwing my hat into the ring for more data/advise.
Recently purchased a '13 with 243k. Knew that 460s are kind of red headed stepchildren from the UR engine quirks and trans issues (several people in my local LC group have had issues). It was cheap and looks/drives great so here we are.
Couple days later noticed reverse "slipping" when backing into my driveway (bit of a incline). Kind of jerky where it'll catch and start moving, momentarily lose that friction, then catch again, repeating several times. Once it gets enough momentum it'll reverse like normal. Hot/cold didn't seem to affect it much, mainly the incline it's backing over. Also no CEL or anything, just a permanent DTC for P2714 that can't be cleared.
Transmission was last serviced at 144k/2020 so it's been a while. I drained/dropped the pan to replace the filter and check things. Fluid looked like it had 100k on it, magnets had normal sludge/nothing out of the ordinary. I changed the rest of the fluid by cycling gears/pulling the return cooler line so the that's all new/good.
I originally thought it'd be worn clutches but from past few pages it seems like it's the inner o-rings hardening/leaking pressure. AT205 is kind of a hack fix but if it works it works, probably add half a bottle for now. Would it also be worth it to add a Hayden 678 at this point? Seems like mine's just at the beginning of these trans failures.

 

[gsi18867]

Throwing my hat into the ring for more data/advise.
Recently purchased a '13 with 243k. Knew that 460s are kind of red headed stepchildren from the UR engine quirks and trans issues (several people in my local LC group have had issues). It was cheap and looks/drives great so here we are.
Couple days later noticed reverse "slipping" when backing into my driveway (bit of a incline). Kind of jerky where it'll catch and start moving, momentarily lose that friction, then catch again, repeating several times. Once it gets enough momentum it'll reverse like normal. Hot/cold didn't seem to affect it much, mainly the incline it's backing over. Also no CEL or anything, just a permanent DTC for P2714 that can't be cleared.
Transmission was last serviced at 144k/2020 so it's been a while. I drained/dropped the pan to replace the filter and check things. Fluid looked like it had 100k on it, magnets had normal sludge/nothing out of the ordinary. I changed the rest of the fluid by cycling gears/pulling the return cooler line so the that's all new/good.
I originally thought it'd be worn clutches but from past few pages it seems like it's the inner o-rings hardening/leaking pressure. AT205 is kind of a hack fix but if it works it works, probably add half a bottle for now. Would it also be worth it to add a Hayden 678 at this point? Seems like mine's just at the beginning of these trans failures.

If you’re planning to keep the truck no matter what, and eventually rebuild the transmission, you’ll eventually need the additional cooler. Installing one now can’t hurt. I’m interested in how much further a cooler can stretch the AT205 result.

Your reverse issues sound more like clutch slippage , which can be directly related to the rubber component problems not allowing full engagement. But I say that because the reverse clutch pack may already be past the point of saving. There’s really no way to determine this before trying the AT205. At the end, my reverse became very rough, particularly backing up my inclined driveway. The more throttle I gave it, the rougher it got. That was the clutch pads coming apart. That was probably The result of having to increase revs to get reverse to engage. It would engage hard, slamming the clutch pack together.

If the AT205 can prevent having to increase revs to get reverse engagement, you may have more time.