Very confusing transmission behavior

[izzy]

Hello 4G forum! I was driving up a pretty steep hill in SF today and my transmission shifted into 3rd and then proceeded to unlock the torque converter and barely get the truck up said hill... significant vibrations, low RPM, just overall struggling.

Does anyone elses do this? It seems like it refuses to downshift to 2nd. Going up a 17% grade riding on the torque converter seems... very wrong when there are gears available.

3rd gear + 17% grade + 15mph is a very questionable shift on the transmissions end. It's acting like it's bolted to a V8 and not a 2.4L 4 banger

Edit: I do use S mode majority of the time because I like to keep the RPMs higher, I almost always use 7th on the freeway instead of 8th (since I go 65, 8th is lugging imo).

I'm also going to drain and fill at 20k and I will for sure take pics of the fluid that comes out

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[Someguysomewhere26]

Haven’t had this specific issue, however as you and I have discussed a few times these transmissions are funny especially with the converter wouldn’t surprise me at all please keep us updated.

I only have 5k on mine still so who knows.

Matter a fact I think this may be very similar to why’s causing the off-road overheating issues just obviously didn’t have the heat issue.

It doesn’t know when to down shift and lock up. As far as vibrations

 

[izzy]

Haven’t had this specific issue, however as you and I have discussed a few times these transmissions are funny especially with the converter wouldn’t surprise me at all please keep us updated.

I only have 5k on mine still so who knows.

Matter a fact I think this may be very similar to why’s causing the off-road overheating issues just obviously didn’t have the heat issue.

It doesn’t know when to down shift and lock up. As far as vibrations

Plugged in the AL80F numbers here:

First gear checks out, that's short enough.

But 1500RPM @ 15mph should be more in the 2nd gear range and not the 3rd gear.

2.4L 4 banger vs 4500lb truck idk you know lol I think Toyota was really trying to avoid the "screaming 4 banger" reputation the 2.7L gave the Tacoma but you cannot escape it, it's a 4 banger it is what it is. Not working with very much inertia here.

I guess maybe the strategy is to unlock the torque converter in a higher gear, and manage the "load" so you can build boost (since the engine is boost limited in 1st and 2nd gear), but why not just rev out the engine in 2nd gear instead of doing the whole rubber-band situation with the torque converter?

I think a shorter rear end would help these trucks out a lot, even with a 4.88 the 8th gear OD is so long >0.652, it won't be noisy on the freeway.

I would definitely be interested in re-gearing the rear end, I think it would help the 8 speed a lot, and probably make 4Hi more usable offroad on any incline.

https://en.wikipedia.org/wiki/Toyota_A_transmission#AX8xx_8-Speed

https://tremec.com/aftermarket/resources/gear-ratio-calculator/

Here I dropped in 4.88 gears and "6th" is actually the 8th gear ratio for the AL80F, 63mph = 2200 RPM which is actually fine, since I ride around in 7th gear @ 65 which is about 2000RPM.

4.56 gears are also an option..

I really think the factory 3.58 gears are just way too tall for a small engine without doing some really wonky tricks to make power.


2nd gen Tacoma V6s came with 3.73 gears, my 2G 6MT was geared nicely to be honest, and even in 6th, if you were going 60mph, you could get on the throttle and the 1GR would eat it up.

3rd gen autos were 3.909, and 3G manuals 4.30. I've never driven a 2GR FKS 3G manual truck, but with 4.30 gears they probably kinda haul ass.

 

[BAQ717]

Plugged in the AL80F numbers here:

First gear checks out, that's short enough.

But 1500RPM @ 15mph should be more in the 2nd gear range and not the 3rd gear.

2.4L 4 banger vs 4500lb truck idk you know lol I think Toyota was really trying to avoid the "screaming 4 banger" reputation the 2.7L gave the Tacoma but you cannot escape it, it's a 4 banger it is what it is. Not working with very much inertia here.

I guess maybe the strategy is to unlock the torque converter in a higher gear, and manage the "load" so you can build boost (since the engine is boost limited in 1st and 2nd gear), but why not just rev out the engine in 2nd gear instead of doing the whole rubber-band situation with the torque converter?

I think a shorter rear end would help these trucks out a lot, even with a 4.88 the 8th gear OD is so long >0.652, it won't be noisy on the freeway.

I would definitely be interested in re-gearing the rear end, I think it would help the 8 speed a lot, and probably make 4Hi more usable offroad on any incline.

https://en.wikipedia.org/wiki/Toyota_A_transmission#AX8xx_8-Speed

https://tremec.com/aftermarket/resources/gear-ratio-calculator/

Here I dropped in 4.88 gears and "6th" is actually the 8th gear ratio for the AL80F, 63mph = 2200 RPM which is actually fine, since I ride around in 7th gear @ 65 which is about 2000RPM.

4.56 gears are also an option..

I really think the factory 3.58 gears are just way too tall for a small engine without doing some really wonky tricks to make power.


2nd gen Tacoma V6s came with 3.73 gears, my 2G 6MT was geared nicely to be honest, and even in 6th, if you were going 60mph, you could get on the throttle and the 1GR would eat it up.

3rd gen autos were 3.909, and 3G manuals 4.30. I've never driven a 2GR FKS 3G manual truck, but with 4.30 gears they probably kinda haul ass.

I think you’re overthinking this. Has nothing to do with the fact it’s an I4, the engine makes more torque than the V6 ever did all across the rev range. I’d consider having your truck looked at because that behavior does not sound normal, at all.

 

[izzy]

I think you’re overthinking this. Has nothing to do with the fact it’s an I4, the engine makes more torque than the V6 ever did all across the rev range. I’d consider having your truck looked at because that behavior does not sound normal, at all.

Idk the T24A-FTS, like most turbo engines is boost by gear and is for sure limited in 1st and likely 2nd, I have a feeling that's why the truck is always in a hurry to get to 3rd gear. It wouldn't surprise me if the 1GR had more immediate torque on tap than T24A, in 1st and 2nd gear.

I'll have my independent shop drain and fill at 20k, ie 2000 miles from now. The owner has connections at a Toyota dealership if the fluid looks... sus

Modern autos being upshift aggressive is pretty normal tbh.

 

[Rocko]

Plugged in the AL80F numbers here:

First gear checks out, that's short enough.

But 1500RPM @ 15mph should be more in the 2nd gear range and not the 3rd gear.

2.4L 4 banger vs 4500lb truck idk you know lol I think Toyota was really trying to avoid the "screaming 4 banger" reputation the 2.7L gave the Tacoma but you cannot escape it, it's a 4 banger it is what it is. Not working with very much inertia here.

I guess maybe the strategy is to unlock the torque converter in a higher gear, and manage the "load" so you can build boost (since the engine is boost limited in 1st and 2nd gear), but why not just rev out the engine in 2nd gear instead of doing the whole rubber-band situation with the torque converter?

I think a shorter rear end would help these trucks out a lot, even with a 4.88 the 8th gear OD is so long >0.652, it won't be noisy on the freeway.

I would definitely be interested in re-gearing the rear end, I think it would help the 8 speed a lot, and probably make 4Hi more usable offroad on any incline.

https://en.wikipedia.org/wiki/Toyota_A_transmission#AX8xx_8-Speed

https://tremec.com/aftermarket/resources/gear-ratio-calculator/

Here I dropped in 4.88 gears and "6th" is actually the 8th gear ratio for the AL80F, 63mph = 2200 RPM which is actually fine, since I ride around in 7th gear @ 65 which is about 2000RPM.

4.56 gears are also an option..

I really think the factory 3.58 gears are just way too tall for a small engine without doing some really wonky tricks to make power.


2nd gen Tacoma V6s came with 3.73 gears, my 2G 6MT was geared nicely to be honest, and even in 6th, if you were going 60mph, you could get on the throttle and the 1GR would eat it up.

3rd gen autos were 3.909, and 3G manuals 4.30. I've never driven a 2GR FKS 3G manual truck, but with 4.30 gears they probably kinda haul ass.

And larger tires makes it a bit worse. Give Tow/haul a try. It holds gears longer and locks up the converter much more.

 

[izzy]

And larger tires makes it a bit worse. Give Tow/haul a try. It holds gears longer and locks up the converter much more.

I did throw oe steelies and 265/70/17s on... I'm guessing around 65lb per corner. Figured it would be a non issue you know because 8 speeds

No tow/haul mode here, no modes at all infact on the base auto SR.

 

[Wife bought my 24 TRD]

I'm expecting something similar,
FROM A DEAD STOP, when I put my foot to the floor, ( traction control, on or off, when transmission is hot or cold, in drive or manually put in 1st ) the truck falls on it's face . The transmission only shifts into 1st after I pedal it, or after what feels like forever, shifts down and takes off.
This is bye no means a loss of power due to the added weight, when I can get it into first year? It'll bark the tires for as long as one wants to, ( not my cup of tea anymore, officially an old man, lol ) so HP is not the problem.
I'm at a little over 16,000 miles and this has been going on for at least 10,000 miles with no definitive answers.

 

[izzy]

I'm expecting something similar,
FROM A DEAD STOP, when I put my foot to the floor, ( traction control, on or off, when transmission is hot or cold, in drive or manually put in 1st ) the truck falls on it's face . The transmission only shifts into 1st after I pedal it, or after what feels like forever, shifts down and takes off.
This is bye no means a loss of power due to the added weight, when I can get it into first year? It'll bark the tires for as long as one wants to, ( not my cup of tea anymore, officially an old man, lol ) so HP is not the problem.
I'm at a little over 16,000 miles and this has been going on for at least 10,000 miles with no definitive answers.

Curious

Sounds like you're experiencing the boost being limited in 1st gear which the tune guys have addressed. Not sure how more boost in 1st will affect drivetrain reliability over time though.

If you're moving anymore than 2-3MPH the truck will take off in 2nd, which is always wonky (ie a California stop). I just bump it into S1 manually, which is jerky but whatever, better than taking off in 2nd with the engine screaming

Oh yeah with a Scan Gauge there's a option to see current gear. What's displayed on the dash is the max gear, ie what it will shift to, not the actual gear selected. It never defaults to less than 3rd even at a stop unless you're moving 25mph+.

 

[Wife bought my 24 TRD]

I will look into a scan tool ?
I thought maybe it was because I put a Sixth element cold air intake in and the stage 1 OTT tune but, ruled both of those out by putting the stock air box back in and having the tune removed, that made it 10x worse.
I know for a fact, it's not shifting down to first gear at a stop., i have tested it everywhere known to man, ( expect for the scan tool tip ).
I will take it back to the tuner and get more information before banking my head against the wall with TOYOTA DEALERSHIP.

 

[izzy]

I'm expecting something similar,
FROM A DEAD STOP, when I put my foot to the floor, ( traction control, on or off, when transmission is hot or cold, in drive or manually put in 1st ) the truck falls on it's face . The transmission only shifts into 1st after I pedal it, or after what feels like forever, shifts down and takes off.
This is bye no means a loss of power due to the added weight, when I can get it into first year? It'll bark the tires for as long as one wants to, ( not my cup of tea anymore, officially an old man, lol ) so HP is not the problem.
I'm at a little over 16,000 miles and this has been going on for at least 10,000 miles with no definitive answers.

Curious

Sounds like you're experiencing the boost being limited in 1st gear which the tune guys have addressed. Not sure how more boost in 1st will affect drivetrain reliability over time though.

If you're moving anymore than 2-3MPH the truck will take off in 2nd, which is always wonky (ie a California stop). I just bump it into S1 manually, which is jerky but whatever, better than taking off in 2nd with the engine screaming

I will look into a scan tool ?
I thought maybe it was because I put a Sixth element cold air intake in and the stage 1 OTT tune but, ruled both of those out by putting the stock air box back in and having the tune removed, that made it 10x worse.
I know for a fact, it's not shifting down to first gear at a stop., i have tested it everywhere known to man, ( expect for the scan tool tip ).
I will take it back to the tuner and get more information before banking my head against the wall with TOYOTA DEALERSHIP.

Yeah that's why I'm always in S mode, I just bang it down to 1st manually. It'll actually rev match downshift into 1st gear all the way up to like 15mph lol Going into 1st gear at 5mph or less nets a gnarly clunk like a noob driving a manual and dumping the clutch I do it anyways tho

Going 4-3 manually also, audibly and physically clunky. I could shift smoother in my 2G with 140,000 miles and ruined synchros

I don't mind bullying the transmission around in S mode, this thread was mostly to see if other people are experiencing the extreme aggressive upshifting, which it seems like yes.

Yeah $120 at Autozone, pretty useful tool if you're tuned you already have a AccessPort no? Those can display current gear depending on the platform.

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