Failing A750 transmission

About 3 months ago I purchased a 2017 ORP with 48k miles. It was a local, single owner vehicle with full service records from the Toyota dealer. Early on I noticed this weird lugging/fluttering sensation when lightly on the gas between 45-50mph. Some googling landed me here and everything is pointing towards TC shudder although I’ve experienced TC shudder in other vehicles and it doesn’t really feel like the normal rumble strip sensation.

The sensation is greatly reduced in 4S although still present. Brake tap to unlock the TC momentarily stops the sensation. It has something to do with vehicle pitch and throttle position. It’s present about 80% of the time while cruising between 45-50mph

I’m pretty sure it’s the TC but what’s confusing me is that it does this at all temperatures and according to Toyota, with the A750 there is no lock up until Coolant is at 140F and there is no Flex lock up until ATF is at 91F. So if it was an issue with the TC wouldn’t it mean that I have no symptoms until I hit those temps?

I’ve done 3 drain and fills over the past 10k miles with no change in symptoms. I dropped the pan the first time and there were no noticeable shavings or sludge in the pan. The fluid was a little dark but smelled normal and no excessive particles floating around.

Other symptoms I’m experiencing are harsh engagement when going from R – D and my 4-5 shift is sluggish and rough. It’s not super harsh but it just clunks into 5th gear. I also experience a lot of jerking/kicking when I’m maintaining speed, take my foot off the gas and get back on there is this jerk/clunk I can feel (feels like driveline slack being taken out).

One other thing is that when I’m maintaining speed, take my foot off the gas and get back on, my RPMs always jump up 200rpm before settling down. I’ve never experienced that in an auto transmission but I guess this is normal for 4runners?

I took the truck to two Toyota dealers who told me they couldn’t replicate the issue which blows my mind because it is very obvious.

I’m just trying to figure out what to do at this point and how to diagnose. I’m thinking valve body or solenoid but I’m pretty nervous about taking apart the valve body.

I come from a 24 Tacoma that needed a new transmission at 2100 miles. I went 5th gen 4runner because of the proven reliability and I cant believe I’m looking at another transmission replacement.

Any tips or advice?

Other things I have done since owning the truck
- replaced all gear oil
- greased driveshaft and slip yoke. (I even dropped the driveshaft to check the U joints)
- Tire Balance and alignment

 

The first place I would start is ensuring your transmission fluid is at the proper level.

When doing your drain and fills, did you do the proper procedure to check fill level?

If you're sure fill level isn't the issue, I would consider a complete fluid replacement rather than just a drain and fill.

Those would be my first steps.

 

hi thanks for the reply.

yea the level is correct. Park on level ground, I use the obd jumper to get into AT temp mode and open check plug until it slows to a dribble. I’ve done quite a few drain and fills on sealed Toyota transmissions and feel confident that I have the correct level.

I was thinking about doing a full flush but even after the 2nd drain and fill the fluid looked pretty much brand new.

also I forgot to add that during the second drain and fill I added a 2oz tube of shudder fixx. I did do a 3rd drain and fill so with some rough math there should be about 1.4oz of shudder fixx currently remaining.

 

Might I suggest cleaning the throttle body very well, leaving battery unplugged overnight. Mine had an aggressive throttle tip in that one may interpret as a jerk or slight clunking going from coasting to throttle. Doing the above improved it enough I don't think about it anymore.

 

My 19 will do it. I flushed the trans fluid myself using the bucket method and haven't experienced it but I don't pay attention to it. There is a transgo repair kit for the shudder or the upgraded valvebody from IPT.

 

hey thanks for the tips. I have done all that and cleaned MAF. Even had dealer reset the TCM after the last drain and fill. I’ve pulled spark plugs, monitored misfires etc

 

Transmission failure at such low mileage is extremely unlikely. Do you know if PO towed?

 

yup level is definitely correct. I don’t think the PO towed. I always inspect trailer hitches on used vehicles and this one didn’t have a single scratch and looked completely unused

 

The 40-50mph rumble is typically the front diff needle bearing.
Its a grumble that you can feel in your feet on the floorboard and in the gas pedal and hear audibly. Its actually the CV wobbling around in an ellipse at speed. For some reason its 40-50mph and its the worst at 45mph. You can typically rule this out by putting the vehicle in 4wd High range and run it on the same stretch of road at the same speed. If this shuts it up, then its the front diff bearing doing its growling. There are service bulletins about this, its an open TSB and your year model would get a whole new front diff.

The trans is kinda wonky, thats the nature of how they tune them now. The older they were the more planted and decisive they felt. The newer models are mushy, less definitive feeling. I suspect you got the same ole trans we all have, and your rumble is most likely the front diff bearing.

 

hey thanks for the info. I had a 2011 Tacoma with the 2.7 where I had to swap the bearing with a bushing after lifting the truck.

I have put this one in 4hi and the sensation is still there.

 

With no clutch material in the pan/drained fluid, I would bet it's torque converter as you suspected.https://www.tacomaworld.com/threads/transmission-troubles-a750e.752294/

 

yea that only thing that confuses me is that mine also does it when the truck is cold. If it was TC or flex lock wouldn’t it only do it once the truck is up to temp?

 

I am not sure. Have you tried this test?

Here is how you can test for a converter shudder from home .

Allow the truck to warm to operating temp . Your converter will not lock up when its cold .
Place the shifter into the overdrive position and drive until you feel the converter shudder .
Once you begin feeling the shudder , use the " Brake Tap Test " to see if the shuddering goes away .

As soon as you feel the shudder , use your left foot and gently tap the brake pedal about 1/4 inch down but leave your right foot steady on the gas pedal .
The idea here is not actually hitting the brakes but manipulating the brake switch . Manipulating the brake switch tells the computer that you are coming to a stop . Your computer will then command the converter clutch to the off position for a couple of seconds . When the converter turns off , your shudder is going to go away for a brief moment .
Because , you only tapped the brake pedal to manipulate the brake switch and you still have your right foot steady on the gas pedal , the computer in your truck will then command the torque converter to re-apply the locking clutch and your shudder will instantly return .

 

yup and that’s what makes me question it being the TC. I put it in my OP, but the TC doesn’t lock until engine coolant is at 140. Mine will shudder when it’s ice cold or hot.

I’ve even done a stall test in Drive and reverse and it stalls out around 2200rpm which I think is normal.

 

Have you considered it could be a bad transmission mount and/or engine mounts?

 

yea I was looking at the IPT upgrade but would prefer to keep it stock. I could get a complete valve body for $1k from Toyota. TC would be around the same and a reman trans from Toyota is about $3k.

I don’t mind any of the above but I just can’t figure out what exactly is wrong and how to diagnose it. I guess the next step would be to pull the valve body and bench test all the solenoids but I really don’t want to do that lol.

I’m seriously contemplating waiting on a 20% parts discount and order a complete transmission. Its a southern car with no rust so I could probably swap it out in a weekend.

 

yes I have. I took a prybar to the trans and watched the motor while reving. Didn’t see or feel anything out of the ordinary.

I’ve basically gone through the entire vehicle minus the internals of the transmission.

 

I had similar shudder/chatter at 48,000 miles with my 2017 SR5. Under my Platinum warranty I got a new tranny & torque converter.
Problem was FlexLock valve inside tranny valve body failed to release timely causing a momentary brake effect. Read up on it-lots of history for Toyota vehicles and a few TSBs.
Here is a couple of my online research screenshots.
Try driving in S4 and see if shudder goes away!
It suggest rebuilding valve body can repair FlexLock system and fix shudder.

 

How did they diagnose this?

 

You're not supposed to drain and fill WS before 30k or T4 before 15k. It can make it too slick. My 2013 Limited did that at 192k and I drained and fiiled. It fixed mine, but I did put some of the old material in the old fluid back in for grit to grip. That said, you're low mileage. Mine has that lock feel and it's usually drive line needing grease. I have 33s and shift points up and down are more noticeable. A lot times it's up and down shifting thru 2-3 gears depending on throttle demand which is weird. There's like a split second hesitation 5th to 3rd or 2nd downshifting. Mine shuttered more in warmer weather. Depending on demand, it will shift 5th>4th on the slightest throttle and 4th>3>2nd, depending throttle. On stock wheels and tire size, the shift points become closer together and you can get the bump and thump with shifting. You probably just need to grease shafts. I had a higher mileage transmission go out in 2001 4runner from changing fluid to early. I have a transmission cooler and in the winter mine doesn't shift into 5th until it gets warm. 4-5th are overdrive bands, 3-2-1 are your clutch gears for pulling power.

 

Lube the universal joints and the yoke maybe?

 

Just had a drain and fill done at 52,500. Took a bit over 5 qts. Feels and drives the same.

 

Do you ever look back at the nonsense you've written?