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.

 

[landtank]

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.
View attachment 4185192

The following are old and from the problem cylinders.
View attachment 4185194
View attachment 4185195
View attachment 4185196

Also found this:

View attachment 4185198

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.

What is that transfer on the ground electrode?

edit: that seems to be the wrong plug, the plug I found was SK20HR11

 

[Rednexus]

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.

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.

At least for the 470, you can get a Denso kit that includes the boots and springs for the OEM coil packs. I did mine at around 200K. I'd suggest that first over replacing all coils, unless several of the coils themselves are obviously burned. Denso coils should last well over 200K - all of mine are still original at 19 years of age. But, if you are missing springs, I bet that is your misfire.

Also - you should replace all 8 plugs at once, and not just a few of them at a time.

Regarding the hose, that is your fuel pressure regulator. I'm not sure it would cause a misfire but it would definitely cause a vacuum leak and probably some funky fuel trims. You can replace it with basic vacuum hose from the parts store.

 

[Schwooby]

At least for the 470, you can get a Denso kit that includes the boots and springs for the OEM coil packs. I did mine at around 200K. I'd suggest that first over replacing all coils, unless several of the coils themselves are obviously burned. Denso coils should last well over 200K - all of mine are still original at 19 years of age. But, if you are missing springs, I bet that is your misfire.

Also - you should replace all 8 plugs at once, and not just a few of them at a time.

Regarding the hose, that is your fuel pressure regulator. I'm not sure it would cause a misfire but it would definitely cause a vacuum leak and probably some funky fuel trims. You can replace it with basic vacuum hose from the parts store.

I will replace all of them soon. I've got a lot going on right now and really just need to do what I absolutely have to.

 

[landtank]

I think the plugs are the whole problem. In general Toyotas have been picky in the past especially with iridium plugs

 

[Rednexus]

I think the plugs are the whole problem. In general Toyotas have been picky in the past especially with iridium plugs

Denso Iridium Powers have been great so far in my 2UZ-FE. I think the old plugs that were in it (around 70K on them) were also Denso iridiums but the extended-mileage version instead of the power version. I can't speak for the UR, however. I usually get plugs and Denso parts on Rock Auto as they are much cheaper than everyone else (half the price of O'Reilly's usually).

FYI this appears to be the Denso boot, seal, and spring set for a 2010 GX460 (actually the same part number as my GX470), but please verify. $47 for all 8; if the coils look fine otherwise this and some dielectric grease is probably all they need.

RockAuto | All The Parts Your Car Will Ever Need

Auto Parts for Your Vehicle at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

 

[BlkGX2011]

Update on the trans rebuild: Reinstalled, back on the road. Reverse works great. Downshift into first from second is a little harsh. Every other shift fine. Kick down better than before. The steel rings were a little tight on a couple clutch packs, so I think it just needs a little break in period.

Currently throwing between 3-8 codes all related to trans temp and solenoids. Shooting the pan with a temp gun didn’t show anything abnormal. Codes are putting the trans into limp mode, can clear the codes for about a half second. If I clear them while driving, trans shifts into correct gear. I’m almost certain this is a valve body wiring harness issue. Something isn’t plugged in properly, maybe pinched/damaged. Had to use more force than I was comfortable with removing the harness during tear down.

View attachment 4184522

View attachment 4184523

Did you reset AT memory in tech stream? That may help with shifting since the ECU is used to the way your old transmission functioned prior to rebuild.

 

[gsi18867]

What is that transfer on the ground electrode?

edit: that seems to be the wrong plug, the plug I found was

Did you reset AT memory in tech stream? That may help with shifting since the ECU is used to the way your old transmission functioned prior to rebuild.

I did not. I had the battery unhooked for almost a week. I’ve deleted all the codes dozens of times. I do not have access to tech stream. Is there a way to do it without?

 

[landtank]

Denso Iridium Powers have been great so far in my 2UZ-FE. I think the old plugs that were in it (around 70K on them) were also Denso iridiums but the extended-mileage version instead of the power version. I can't speak for the UR, however. I usually get plugs and Denso parts on Rock Auto as they are much cheaper than everyone else (half the price of O'Reilly's usually).

FYI this appears to be the Denso boot, seal, and spring set for a 2010 GX460 (actually the same part number as my GX470), but please verify. $47 for all 8; if the coils look fine otherwise this and some dielectric grease is probably all they need.

RockAuto | All The Parts Your Car Will Ever Need

Auto Parts for Your Vehicle at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

I have a rather big following and field a lot of questions. Iridium plugs in a Toyota that is not spec'd to have them has been an issue for quite a few people.

Curios, whats the upside of not running the recommended plug?

 

[gsi18867]

I have a rather big following and field a lot of questions. Iridium plugs in a Toyota that is not spec'd to have them has been an issue for quite a few people.

Curios, whats the upside of not running the recommended plug?

I put Denso Iridium IKH20TT 4704 in my 1GRE-FE 2013 4Runner.

Should I stay away from Iridium for the 460?

 

[landtank]

I put Denso Iridium IKH20TT 4704 in my 1GRE-FE 2013 4Runner.

Should I stay away from Iridium for the 460?

I only run the recommended plugs with the exception of a boosted engine, those get old school copper plugs to ward off detonation.

Iridiums have an extremely hard center electrode which is good for longevity but bad for cooling. The electrode cools during the intake stroke. There are a lot of variables, but if the tip doesn't cool enough for the power stroke there could be unwanted detonation.

 

[Rednexus]

I have a rather big following and field a lot of questions. Iridium plugs in a Toyota that is not spec'd to have them has been an issue for quite a few people.

Curios, whats the upside of not running the recommended plug?

GX470s are factory spec'd with a Denso Iridium Long Life plug, per the Lexus parts website (SK20R11)

https://parts.belllexusnorthscottsdale.com/p/Lexus__GX-470/Spark-Plug/62973200/9008091180.html

Those are the plugs I pulled out of my GX470 at 200K. I figure they were put in by the Toyota dealer who installed the timing belt just before I bought the rig at 135K. I never had any issues with the plugs and proactively replaced them, with the Iridium Powers this time, as I don't mind replacing them more often (they do loosen, anyway). It ran slightly better with new plugs - fuel trims evened out a bit side-to-side.

The OEM GX460 plug appears to be the same Denso Iridium Long Life SK20R11:

https://parts.belllexusnorthscottsdale.com/p/Lexus__GX-460/Spark-Plug/63354147/9091901191.html

Interestingly, the 4Runner 5th gen spark plug starting in 2014 is also is a Denso Iridium Long-Life (SK16HR11):

https://toyotaparts.ourismantoyotaofrichmond.com/oem-parts/toyota-spark-plug-9091901233/

Unless Toyota is showing the wrong pictures on their parts websites, Denso Iridiums are the OEM spec for the GX470, GX460, and 2014+ 4Runner. I certainly can't opine on issues others have or have not had by running them in other Toyotas, nor how big your following is or isn't, but OEM spec'd Denso Iridiums have been great in my GX470, which is why I bought them again .

 

[Schwooby]

Took a ride this morning. Wanted to check it at highway speeds.

Got another misfire on cylinder 4. The misfire didn't follow the coil, so it has to be the spark plug, right? I didn't see anything crazy in there to indicate a big leak or problem :/

It's also throwing p2441 now: secondary air filter issue? Anyone fixed that before?

 

[Rednexus]

Took a ride this morning. Wanted to check it at highway speeds.

Got another misfire on cylinder 4. The misfire didn't follow the coil, so it has to be the spark plug, right? I didn't see anything crazy in there to indicate a big leak or problem :/

It's also throwing p2441 now: secondary air filter issue? Anyone fixed that before?

I would suggest running a compression test on all 8 cylinders (you can rent a compression tester for free from most auto parts sores), with wet and dry compression recorded to rule out internal engine problems. Assuming you don't have an internal engine problem (i.e, compression is within Lexus specs for each cylinder and No. 4 is no different than the other cylinders) I would then 1) inspect the coil bodies for cracking/signs of wear 2) replace the boots/springs/seals on all 8 coils with the Denso kit I linked, 3) replace any coils that are damaged, and 3) add in 8 new, matching Denso spark plugs (either Iridium Long Life or Power; I like the Powers in my 2UZ-FE and they are cheaper than Long Life's).

I suspect that your issue is either mis-matched plugs and/or an issue related to a coil (either the coil itself or the spring/boot), considering you noted several are missing springs. Even though they misfire didn't move with the coil, the boots are wear items and should be replaced when replacing spark plugs. However, it's very little extra work and no cost with a rented gauge to check compression while you are doing this to verify that you don't have a burned valve or blown head gasket. The misfire not moving with the coil could point to a burned valve, although I've never heard of a UZ or UR burning a valve. If it does have a burnt valve, it will show up immediately in the compression est.

If you do have an internal engine problem, you can then return the spark plugs and coil boot/spring/seal kit and get your money back, and figure out what to do after that (as it will be a big/expensive repair).

 

[Schwooby]

I would suggest running a compression test on all 8 cylinders (you can rent a compression tester for free from most auto parts sores), with wet and dry compression recorded to rule out internal engine problems. Assuming you don't have an internal engine problem (i.e, compression is within Lexus specs for each cylinder and No. 4 is no different than the other cylinders) I would then 1) inspect the coil bodies for cracking/signs of wear 2) replace the boots/springs/seals on all 8 coils with the Denso kit I linked, 3) replace any coils that are damaged, and 3) add in 8 new, matching Denso spark plugs (either Iridium Long Life or Power; I like the Powers in my 2UZ-FE and they are cheaper than Long Life's).

I suspect that your issue is either mis-matched plugs and/or an issue related to a coil (either the coil itself or the spring/boot), considering you noted several are missing springs. Even though they misfire didn't move with the coil, the boots are wear items and should be replaced when replacing spark plugs. However, it's very little extra work and no cost with a rented gauge to check compression while you are doing this to verify that you don't have a burned valve or blown head gasket. The misfire not moving with the coil could point to a burned valve, although I've never heard of a UZ or UR burning a valve. If it does have a burnt valve, it will show up immediately in the compression est.

If you do have an internal engine problem, you can then return the spark plugs and coil boot/spring/seal kit and get your money back, and figure out what to do after that (as it will be a big/expensive repair).

There are def some underlying issues here.

Also, this is the plug I pulled from Cyl 4 this morning. I've replaced it.

This thing is clearly ****ed lol