OFFICIAL: MY22+ Toyota Tundra - Throttle Lag/Hesitation From Stop Issue(s) - T-SB-0111-22

Have a '23 that I purchased in January and I have the lag issue and can reproduce. It is extremely annoying and i have to be extra careful to not try to gun through traffic if I have just stopped or am rolling through a stop. Going to ask about it at my 10k mile service tomorrow.

 

Not sure if it's related to this topic but does anyone feel like the transmission is slipping?
Example, you're coming to a stop light and say you don't come to a complete stop cause light turned green, you step on the gas and and the RPMs go up but truck responds very slowly. My thought was it doesn't down shift quick enough and when you step on the gas it's in say 5th grade or higher instead it should be at least 3rd if not 2nd. I've also had it happen from a stop. I've had the lag update a few months ago and was running good. Also I might add the it acts like this lately around 85%of the time. I called my service advisor and from what he can tell from my description that it could be transmission slipping.
Anybody else experienced this? Anything would be much appreciated.

 

We were surfing on the weekend and the rear ballast tanks would not drain. So we towed home, I pulled the plug out of the boat and parked on a steep hill....and emptied the bags ( 2000 gallons of water ) into the hull and let it run out.

Once done I went to leave and was surprised at the effort to get it rolling up this hill. Hybrid 1794, boat at 5500 lbs on trailer. My 2012 would of yanked that thing. I wont say it was lag...but weak comes to mind

 

I really feel it is slipping. Like I said earlier, it's not all the time and when it's not slipping the truck is super responsive. Next Thursday in taking it in.

 

Probably the exact same feel but I would compare my boat experience to having to tow some dude that is stuck in the mud. Keep laying the power on with minimal movement and then ..Boom...you get rolling. Best analogy I can come up with.

I also remember it is 5000 LBS boat getting towed up a steep steep hill with a 6 cylinder. Maybe I need to understand the hybrid / Turbos better.

Good note, boat is fixed and its Surf up on Sunday Funday

 

I did some driving with a scan tool and it seems like the Transmission can stay in 3rd gear until complete stop and if that happens and you get back on it lightly it won't downshift to get going again an that make it not accelerate very well.

I can't say I've experienced that regularly though. The lag I've at least confirmed that there was a delay in requested throttle and commanded throttle PID's indicating that the accelerator input was being ignored. When not having the lag, the requested and commanded throttle values match each other within a sub second interval.

 

That's very helpful. Thank you so much for digging and that makes perfect sense. I will be sharing this with my service advisor.

 

Hope you find out more, not really sure how much improvement they can make for you, notably no Toyota auto transmission ever handled low speed rolling starts for me that well and its a little nit picky on my part.

 

I think without a drive mode select its always the "normal" D mode.

No confirmation but I believe using "S" mode the transmission follows a static shifting schedule and doesn't use any learning/ai/etc in addition to locking out any selected higher gears.

At least that's what it was in 3rd gen Tacoma.

 

Well I would sure like to know what it takes to use 9th or 10th gear...never seen it regardless of drive mode (would expect Eco at highway speeds of 70-75 on flat terrain...highest I've ever seen is 8th).

 

If it's not downshifting during a rolling stop automatically, what if you used sequential shift to force it into 2nd or 1st? Has anyone tried to reproduce lag when using sequential? I haven't experienced what I would consider lag yet in mine.

 

I am refining the process to collect data but I have some data to start from todays drive. When I get the process refined and better data I'll start a new thread. I will probably only collect data on Saturdays.

I didn't experience the bad lag today. (>3 second delay between accelerator and throttle response.

I captured some starts that responded perfectly, you can see that the throttle command/request changes very quicky to the accelerator pedal and note that not a lot of fiddling with the pedal was seen.

However in 2 other starts I see that there was about a second delay where the accelerator is pressed and no throttle seems to change, so the accelerator is "hunted a little bit" and it does respond and get going after a second. I call this the "annoying lag" as its just a little perturbing.

 

The only anodically thing I want to look into a bit deeper is that it appears from the data log that the vehicle speed pid data seems to be lagging behind the actual speed by several seconds.

 

Do you have gear position PIDs? Of course the throttle is electronically controlled and could be controlled during a shift to stay closed to help the shift complete better. Kind of like how you lift off to accelerator in a manual transmission car when shifting. I think you could draw more conclusions from something like command torque vs. torque achieved or something like that to tell you what torque the engine is actually making.

 

Gear (Shift Status) is in the Transmission Live data, and doesn't appear in the Engine Live data, however the throttle data is not present in the Transmission live data. Techstream allows to log both computers at the same time, but my laptop setup isn't very reliable. I'm looking to add a few more I think I can log 8 pids from the engine at one time with the tool I can tuck away so its out of the way.

 

I got these PIDS from T-TT-0615-20 which was when toyota was trying to fix the 3rd gen tacomas and other 2GR-FKS/6 speed complaints.

So I will see about being able to log this many in a reliable way.

 

Thank you so much for this graph. I will be showing this to the tech tomorrow. I will keep you posted.

 

Good luck...

Techs follow instructions from Toyota. And there aren't any instructions besides the TSB flash update that doesn't quite help for more than a couple of weeks

 

Keep in mind this was the behavior of my truck and not your truck. I have a new setup with the actual tech stream software I am able to pull all the pid's at once (Techstream appears to have a preset "Gas Throttle" for this already so its something I guess they deal with a lot) Shift status and gear are available to be logged as well.

 

That sounds complicated, and makes me think that you may find a fix for us all

 

Well, just a couple of you guys told me, they won't be able to fix anything. Thanks for your guy's input.

 

I was able to capture one of the little hesitations pulling out of the driveway, seems to be correlated with a quick tap on the break and a downshift from 2 to 1. Unfortunately I didn't realize in the techstream logger it default to stop logging after 5 minutes so I didn't capture a full drive with many lowspeed starts to get more correlation. I will fix this on my next drive. I spent all day finding the best tool to line up all the exported data. I'm close to having the system nailed down to consistently log data.

 

Here is a zoomed in one, each data point is 125ms. It looks to me typically the throttle is responding within 250ms of an input, so that's why the other one feels weird.

 

Wow dude. That freaking awesome. If you don't mind could I send this to my service advisor?

 

I'm fine with sharing as long as its clear the data is from my trunk and not your truck, however if it does visualize what you feel then that was one of my goals.

The current goal is to quantify the lag (how long and what did things look like)
Hopefully this will actually lead to being able to replicate the issue more consistently on-demand. I think once that happens its a lot easier to get it fixed.

I actually have 100 different parameters logged though most of them seem irrelevant. I am seeing though the data the the computer is responding to input within 125 ms of a throttle input but in the lag cases its not doing anything substantial for nearly 1 second. For example in the capture lag, The pedal was pressed to a value of 32, but the engine rpm in the following full second only increases by 210 rpm, after which it seems like the truck over responds (partly to increase throttle due to lack of response) causing a quick lift off correction.

 

I'll keep posted on what they say after getting this info. Hopefully they can send this to toyota.
Been thinking about getting a pedal commander or the jb4 but I plan trading this in on a 2024 tacoma trailhunter. Anyways, much appreciated for your work on this.

 

I still want to know if yota limits throttle application from pedal if steering wheel is turned more then xyz degrees.

This was a MAJOR throttle lag issues that plagued ecodiesels that was not part of ECU of engine tune but the ECU of the transmission module. You would have limp dick throttle and all of a sudden it comes on and everyone blamed turbo lag

Also this truck, has various tunes, need to find thate one guy who had throttle lag on a limited, jumped into a SR5 and was like yea this issue is gone on this model

I only had like 1 weird incident in traffic, but common if you know how trq converters work, needed to accelerate quickly, stop that and need to accelerate quickly within 1-2 secs again and you will always see some throttle lag. Your trq converter and tranny is fighting to find a gear for you guys s all that is

 

I do plan to take all the data to my dealer next month when its in for regular service.

 

9th and 10th are very tall when paired with that 3.31 axle ratio. Especially it you are running bigger tires. Youre asking the motor to turn a low rpm pushing a massive brick through the air

 

Running stock tires on a Platinum.