Gx470 losing power/ acceleration (1 Viewer)

[Tgood]

Hi all-

Had an odd experience in my GX470 on the highway yesterday. I was returning from a snowboard trip from Santa Fe to Albuquerque @ about 82 mph on the interstate (that’s barely keeping up on I25) . Out of no where the gx470 started to downshift to 4th to maintain the speed. It couldn’t hold the speed in 5th.

When I pulled off for my exit and attempted to pull away from the stop light, it had very little power. Maybe 20% of normal acceleration. Very sluggish to say the least. I parked in the garage and drove it this morning, it was fine. All the power was back and it accelerated normal.

I rebuilt the leaking transfer case with new o rings last weekend to fix the common leak, and I also did a drain and fill of the transmission. When I drained the transmission I popped the weep plug first and about 2 quarts came out. I popped the drain plug and only got another 3/4 quarts, which I thought was very odd. The truck was cold so I’m not sure why so much fluid came out of the weep hole.

I’m wondering if the sudden loss in acceleration is related to the drain and full of the transmission (I did it according to the FSM and all the youtubers). Maybe the fluid level is off?

Anyone else experience this sudden loss of power and have it correct itself after sitting overnight?

Has me spooked to say the least.

It’s a 2004 GX470, so it doesn’t have the secondary air injection.

 

[HomersCanyonero]

I had a very similar experience. I was at altitude in the mountains in mammoth lakes and I lost power on the way back to the city. Just like you describe.

I was struggling to go 40 mph after going 70 mph in the highway. This lasted a good 15 minutes and I just couldn’t accelerate past 40 mph. Luckily there was some traffic and I was able to stay in the slow lane during this time.

Then all of the sudden everything was back to normal and I was going 70 mph again for the next two hours. Problem never came back.

I replaced the engine air filter and cleaned the MAF sensor. Also, after this acceleration incident I got a constant P0420/P0430 that I couldn’t shake for like 6 months. I ended up replacing my integrated cats with oem Lexus cats. I had also replaced the O2 sensors.

The acceleration issue never came back and it’s been over 2 years. I never really figured out what happened and don’t really know if the repairs I made fixed it. I just know the problem never came back and I’ve travelled back to the mountains, desert, daily driver, trips to Baja, and no issues.

I hadn’t done any repairs prior to the incident.

 

[Tgood]

I really appreciate your input. Sounds like I might have a bigger issue. Just took it out again and when I put it in reverse it wouldn’t engage. I put it in 4lo and it finally engaged with a bit of shuddering.

When I changed the transfer case o rings and fluid, it was pretty low on t-case fluid. I hadn’t even noticed the leak.

I’m wondering if I blew out the transfer case running it somewhat dry.

Thanks again for the input, I’d appreciate any other words of wisdom from the forum!

 

[Rednexus]

Did you throw any CEL codes? A large loss of power like that is typically due to the vehicle going into limp home mode for some reason - and it will usually throw a check engine light. I *think* the GX will also go into limp mode if transmission temperature gets too high, so was your AT TEMP light on perhaps?

Definitely check the transmission fluid level. I think your '04 has a sealed transmission. There is a specific procedure for checking the level that requires getting the transmission up to 105 degrees F and removing the level plug, then adding fluid through the fill plug on the back of the transmission. You can check transmission temperature using a OBDII wifi/bluetooth adapter and an app like Torque Pro to know when to open the level plug. The fact that it would not go into reverse makes me think that perhaps the transmission was low on fluid and overheated - maybe throwing it into limp home mode and resulting in the lack of going into reverse today. If so, hopefully you are just low on fluid and it can be addressed with a fluid change, but there would be some chance the whole transmission is cooked. FYI - the drain/fill method is not the preferred way to change the fluid (IMO), I prefer the full flush with a pan drop that replaces all 15 quarts, and checking the level at the very end at 105 F.

It seems unlikely that the T case could cause these issues - it has no computer communication with the rest of the vehicle and would likely just outright fail and make a ton of noise if there was a issue.

 

[phishtaco]

Stuck caliper? Common issue.

 

[Tgood]

Hi all.

Really appreciate everyone’s thought on this. No CEL. I’m getting some shudder and vibration in reverse, or it doesn’t engage at all. I was leaning towards the T-case as I couldn’t get it to engage in 4hi, but when placed in 4lo, it would engage, albeit with shudder.

I took my dad to the airport this morning, it ran fine on the way down, but on the return trip it started again. Made it home, but had the same problem.

I’m going to drain and fill again this afternoon to eliminate the low fluid concern. I’ll make sure and follow the detailed instruction in the FSM, brining it up to the proper temp and all. I’ll report back and update the post.

Hope everyone has an excellent Sunday.

Cheers

 

[Tgood]

Stuck caliper? Common issue.

I thought maybe at first.. when you press the accelerator you can definitely tell it’s a fuel delivery/transmission/ignition/limp mode issue. No brake smell..

 

[SteveH]

Dying fuel pump or intermittent clog in the fuel system?

 

[Rednexus]

I would really recommend a full flush from the AT cooler along with a pan drop and filter change. You'll then get all the gunk out of the pan and all new fluid. If you fluid is cooked and you drain and fill you still have 75% cooked fluid in your transmission, which may continue to harm your transmission. If it is indeed cooked, get all of it out plus the pan gunk.

 

[Tgood]

Thanks again for advice and input-

I drained the transmission today and found less had come out then my original drain and fill, about 3/4 of a quart less. I think I may have not had the truck running when I did my original drain and fill. Even though I did the drain and fill last weekend, I just don’t remember if i had it running when checking the overflow valve.

I ended up adding about 2 quarts more than I did during the first drain and fill today. I jumped the pins on the OBD port, and left the engine idling when filling.

I drove it a few miles and it felt good. Put it in reverse and no slipping or shuddering. I’ll run it on the freeway tomorrow and see how it goes.

Hoping it was low transmission fluid that caused the issue, I’ll report back!

 

[Rednexus]

How did the fluid look? Nice and red or dark/burnt?

 

[Tgood]

How did the fluid look? Nice and red or dark/burnt?

Very dark. Didn’t smell burned, but not great for sure. It was slightly better than the first drain and fill. I’m going to follow your advice and do a full fluid swap this weekend, dropping the pan as well.

I’m sure it’s never been done, I’m at 142k

 

[Tgood]

Well, did not seem to help. Still loosing acceleration, even at city speeds. It’s fine for about 15 minutes and then just drops power.

In reverse it’s slipping pretty bad, this only happens when it’s warmed up also, it revs but feels like you have the clutch in on a manual car.. so I’m thinking transmission or transfer case issue.

No check engine lights

 

[Tgood]

Well, finally got a check engine light and a 2 solid VSC lights (no squiggly traction light though).

Thought it might be the gas cap failure but I highly doubt it.

I pulled the code and it’s a P2714. Stuck solenoid open “D”. I googled the code and my truck has all the symptoms of a bad solenoid in the transmission.. sad day!

Anyone have experience with this? Not sure if it would be worth having it fixed or going with a new or salvage unit.

 

[Rednexus]

I'd probably run it to a transmission shop experienced with the Aisin A750F for a diagnosis at this point. I think the actual solenoid replacement is pretty cheap/easy, but there could be more things wrong.

 

[Tgood]

Yeah @red nexus,, that’s good advice. I’ll end up going that route and update the thread.

 

[Tgood]

I ordered the SLT solenoid from Toyota. Gonna drop the pan and replace it. Quite possibly destroyed the transmission, so the solenoid might not work.
Called a local Toyota specialist, they don’t even want to try the solenoid, pushing a full replacement-either reman or used.

Used- $2400 OTD
Reman- $3900 OTD

Figured I should try the $100 solenoid first, although just because the error code is coming from that solenoid, it does not mean that’s the issue. Could be a bad pump or a few other things.

Not sure if it toast, but I’ll update the thread.

 

[Rednexus]

Good luck. Hoping it might be the solenoid!

 

[racwerx]

Had a very similar experience with my 06. Same symptoms (lack of power/shifting). Mine would usually show up after a hard stop and sometimes a hard clunk if I accelerated too quickly from the stop. This eventually led to a snapped coupler between the transmission output shaft and t case input shaft.

Thought it was the common Toyota clunk and greased the shafts. Being that it had been an intermittent problem, it was hard to diagnose. It went away and I thought I had solved the problem until it came back and snapped the coupler. Improper transmission fluid level was definitely the culprit.

After dropping the t case and extension housing, we were able to pull the old snapped coupler and replace it with a new one we pressed off of a brand new t case input shaft. Dropped the trans pan and replaced the filter along with a drain and refill. It's now shifting butter smooth. No more hard shifts, stalls, lack of power, or clunks. Night and day difference. Definitely learned not to take previous owner's word on anything maintenance related (said it was just serviced at a dealer prior to me buying it).

 

[Tgood]

Had a very similar experience with my 06. Same symptoms (lack of power/shifting). Mine would usually show up after a hard stop and sometimes a hard clunk if I accelerated too quickly from the stop. This eventually led to a snapped coupler between the transmission output shaft and t case input shaft.

Thought it was the common Toyota clunk and greased the shafts. Being that it had been an intermittent problem, it was hard to diagnose. It went away and I thought I had solved the problem until it came back and snapped the coupler. Improper transmission fluid level was definitely the culprit.

After dropping the t case and extension housing, we were able to pull the old snapped coupler and replace it with a new one we pressed off of a brand new t case input shaft. Dropped the trans pan and replaced the filter along with a drain and refill. It's now shifting butter smooth. No more hard shifts, stalls, lack of power, or clunks. Night and day difference. Definitely learned not to take previous owner's word on anything maintenance related (said it was just serviced at a dealer prior to me buying it).

Intersting.. did you ever get a CEL from it? I don’t have any clunking, stalls, or hard shifts. I’m pretty sure it’s going in to limp mode due to incorrect pressure in the transmission. My issue seems like a bad solenoid/sensor/pump.

At this point I’m not sure the replacement solenoid will work, but figured I’d try before going the replacement route.

Speaking of replacement re-man units, it seems every re-man company gets terrible reviews. I think I’ll try and source a low mileage used unit should the solenoid replacement not work.