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

Here is one I saw with what fell like and logged about a .5-.7 second "delay" Followed by me stopping and then going again that felt 100% normal/perfect.

I'm noticing when there is delay, the Output speed sensor is non zero even though in both starts the vehicle speed was about 3km/ph(1-2mph)

It also looks like in the lag situation the load vehicle load is higher also it looks like its first starting to try to close the wastegate but the rpms are two low for any boost to be generated.

Also being in 2nd and triggering a downshift to 1st seems to be a factor as well, vs being in 1st gear already.

 

I just started to log wastegate valve positions. Reviewing the last drive it almost seems like values at low speed that are in the 78-79 deg range seem to have more lag than similar starts with the wastegate at 80-82 deg.

I'll see if I can correlate that to something that might be why its "random" as there's no way you can manipulate that driving.

Still seems to be a specific speed (output shaft) and conditions maybe leading to a slightly wrong load calculation that applies too little throttle so theres a delay until that calculation corrects.

 

I have a question, is the Auto Start/Stop button disabled or enabled? I always let my Auto Start/Stop feature disabled because A) I want the turbo's to cool down B) less wear on the starter. I am a believer that the Auto Start/Stop feature is a wasted idea. I don't remember which car i was into in 2017 on a rental and had that it drove me bonkers, was out on the highway at 35C it would kill off the A/C GRRRRRRRRRRRR I am currently looking into the Auto Start/Stop Bypass kit.

 

I'm doing all my testing with stop/start enabled (default) I haven't seen for me the feature have any relation to the condition. What I am seeing sofar with my data that all lowspeed starts (almost coming to a stop and then going) are having some sort of slow ramp up of the throttle, but some are feeling more laggy than others and I'm still trying to marry up what i felt to what the data says.

I do feel that the really bad lag is a thread the needle type situation where you hit a very specific set of values so its likely a large set of people just never hit it.

I'm finding lag is falling into a few buckets

When there is < .5 second delay - Just feels a little jerky
When there is < 1 second delay - Annoying
When there is > 1 second delay - Rage/Fear situation.

I haven't captured that 3rd one yet because its very rare.

I don't think drive modes are related, other than they seem to change the ramp up time of the throttle, so eco can extend the lag by delaying the throttle further after its starting to respond, while sport ramps up quicker after its responding, but I don't think they are changing the initial delay.

 

I'm looking though more data, my current theory is as follows:

If you can get into a certain situation where the output shaft speed somewhere in the 50rpm range (seems like this value only gets logged in 50rpm increments) While the vehicle speed is relatively high (> 6kmph) the response to adding accelerator seems to be to target boost instead of adding throttle. At the low rpm you are at in this condition (700-900rpm) the turbos can't add any boost. This seems to continue until the speed gets lower than the throttle is added. I suspect if you can maintain that situation (such as a small incline), you can maintain that condition for an extended time before the speed drops the needed like 1kmph to request more throttle.

I don't know how that would pertain to hybrid though, the hybrid should be adding electric motor in this range.

 

Seriously this is the greatest find. I had never considered the transmission but this will very much help trying to describe this to a service tech. The description of trying to start out in a higher gear and it being very sluggish, this is the perfect way to describe it in laymen’s terms

 

So Far I've been finding that actually I'm in first gear when the lag happens. The main thing I've been milling though is that the accelerator/throttle data looks very similar for many stop/starts but some feel really laggy.

I stated logging boost target data. At least the last drive I found that the one specific start that felt laggy, it appears there is a boost target being set at a very low speed. I suspect there's table(s) that define when to add boost or add throttle and there may be a specific bad value somewhere.

I just need more drives/data now to see if there is a correlation. 2nd Screen shot shows a similar condition but very little boost is targeted initially until the rpms ramp up.

 

I have the raw csv's with over 68 parameters if someone "knows" someone to look at them or knows what exact pids to look at. The current mix of what I'm actually looking at seems to be the best for at least seeing what was going on with my pedal/engine/speed/tranny/boost.

 

@wedemmoez help needed

 

There are a few general observations right now.

- When you feel this it feels like the engine completely is not responding, the data seems to point otherwise, its responding but only by a fraction of what it should be. (feeds into a bad boost target theory)
- It seems like the vehicle speed pid lags way behind what the actual speed is by almost 2 seconds, the output shaft speed seems to be more accurate as to the actual speed.
- Partly because of above what you feel the vehicle is moving at is different than what the computer sees.
- Because of the above what feels like a full stop may not be a full stop. (I have no lag I can find when the output shaft speed registers 0)
- I think probably a lot of people experience this now and then but since its usually under 500ms most people don't notice it.
- All lags seems to occur after a downshift command to 1st, and I have not seen data of any lags in 2nd gear.
-The lag seems most prevalent to be at places where there I am at a backwards incline (Rear slightly lower than the front)

 

Wound up driving around a bit logging stuff today, Absolutely no lag.

I did check the specific situations vs when I felt lag. Unfortunately I didn't log all these pid's a few weeks ago when I first logged some lag.

Its seems you need to have a NT Speed >= 300 Output axis speed = 50, and Vehicle speed > 5mph and be in 1st Gear (Keeping in mind this lags behind the dash speedo)

These are my suspected conditions but it may be only a subset and not all 4.

Its very hard to actually get into this state. Every stop/start today the NT was 250 or less, and the Output shaft speed didn't hit 50 except once when the vehicle and NT speeds were already very low.

 

Here is the best I have from all my data sofar:

If you get going into 2nd gear or above and then slow down and apply the brake enough that it downshifts to 1st gear, and then apply the throttle.

At the time you apply the throttle again if:

If the NT Speed sensor >= 200 rpm
And the Output shaft speed = 50 rpm
(Both pids are registered in 50 RPM increments)

The engine seems to respond very slowly (Command throttle and load calculations don't increase very fast)

So far the exit condition for this case is that the engine RPM gets above 950 RPM. That seems to be the point the engine load and throttle appears to start responding normally. On average that is taking half second or so to achieve that but if the rpm is especially low at the time of the start it can take longer for the engine to reach 950 rpm.

There doesn't seem to be any boost target/wastegate actuation that correspond to having the delay.

It is very difficult to replace these exact NT and output shaft speeds, however if someone has the ability to have a co-driver look at the data real-time its possible to find the holy grail of being producible on demand. I personally cannot do this safely with my setup.

If I get to 100 rpm or 0 rpm on the output shaft there doesn't seem to be any lag regardless of NT speed.. If the output shaft speed is 50 and my NT speed is 150 or less, there doesn't appear to be lag. Does seem like a thread the needle type situation.

 

I have an early '23 and mine has the throttle lag from a slow roll and surge from R to D when the engine's cold.

 

Hopefully Toyota will start paying attention to this issue and get it fixed.

I'm surprised it's taking them so long to develop an effective and reliable fix for this...

 

Responses here would indicate that the TSB for the surge works, but the TSB for the lag is hit or miss.

 

I was in for service today and brought them all the data, the advisor and tech did spend a considerable time on it. The tech was able to confirm the lag on their test drive. They did open a TAS case. TAS did have them do a TCM reset including having the battery disconnected for 30 minutes. Now that they reset the TCM they want me to drive it for a while to re-learn driving profile

I am not sure what the exact TCM reset procedure is. They did encourage me to continue logging data and bring more data back to them if it re-occurs to update the TAS case.

 

those are nice techs, put them in bottle and hide them away from the bad people

 

Rlc, do know that all of us sufferers rooting for you, and we wish you lots of energy and strength to figure out this issue for all of us!!

Let us know if we can help somehow

 

Yeah I'm not confident that the TCM reset is a long term solution unless just something weird goes on and it learned something bad. Regardless I am going to keep logging so that if something does get better or if it gets better and changes I had the data.

If anything if you take your trunk in for service for the recall at least ask to look at the issue or at least preform the TCM memory reset.

Generally though this is a positive direction, tech verified the issue and the TAS case is open.

 

The thing is that a 1/2 second delay issue may be categorized as "normal" by Toyota... And they may not really try that hard to fix this.

 

Thank you very much @rlc177 for your research and documentation!

I have a '23 TRDOR with just under 6k miles and occasionally have the lag. Mine is most noticeable when I'm leaving from my parking spot at work in the afternoon. I asked the S/A during my 5k check about it last month and he just stated to give it time as the pickup is adjusting to my driving habits. I didn't think much about it until last week when I was sitting in traffic and experienced the lag and when I pressed the pedal more, it surged forward. Fortunately, the car in front of me had already moved 1-2 car lengths but did cause me some concern if it were to happen again while trying to get out of traffic. I first noticed within 1k miles when shifting from reverse out of my driveway to drive and there was a lag but I just attributed to that as early morning and the vehicle not warmed up yet.

I'm taking it in tomorrow and will ask about the TSB-0111-22 and the TCM memory reset that @rlc177 has documented.

JR

 

Sounds good, I had a similar experience in traffic. I've yet to be able to log one of those events it only happened once in stop and go traffic. I mostly have the garden variety .5 second or less lag. I did log one lag event after the TCM memory reset but it was very short duration of 200ms.

You can reduce the surging by not continuing to press the pedal down more but just waiting for a response. Might be a good time to try to check the speed and rpms.

I don't think its something that will be fixed soon but if more and more cases come in that may lead to more resources looking into the issue.

My experience with the 3rd gen Tacoma's in 2016 was the issues were reported but the final calibration updates didn't come out till July 2018.

 

Funny thing, I had issue with my oil pressure Gauge showing low oil pressure, and I had dealership do the TSB-0022-23 (thx Ryan!) for this issue which did ecm flash.

My throttle lag went away now and truck drives so fast and so so enjoyable now! Let's see if this lasts...

 

My June 20, 2023 build hasn’t displayed any of the acceleration lag/surge problems described in this thread. It accelerates smoothly and predictably from a complete or rolling stop. I use the normal drive mode, and always turn the auto stop/start feature off.

Thanks to you guys who have been spearheading a resolve to this. Apparently Toyota has noticed and is making the necessary changes to the newer builds. Hopefully a recall fix will be available for the affected trucks, soon.

Matt

 

Got my pickup back yesterday and service writer said they couldn’t replicate issue. He also checked and the reflash was already done at the factory. I typically drive in Eco mode but may start driving in Normal mode and see if it ceases.

JR

 

I found this happening occasionally in ECO mode, stopped using it, normal mode and have yet to have it happen again. Never found any real benefit of ECO anyway.

 

#3 happened to me while stopped with a car not paying attention approaching from behind at 65 mph on a two lane highway. Nearly smashed into me. The delay was at least 2-3 seconds. Very scary.

 

I'm going to try to start logging data from the Transmission Computer instead of the engine computer. It still seems like the issue seems to revolve around a higher than expected NT (input speed) when applying the throttle.

I notice that the transmission is logging a of "Large Increase In Engine Speed" Record of Behavior (RoB) events and want to see if this aligns with any lag events. Unfortunately I don't know much about the vehicle control history events, and if these events are normal random stuff or actual problems. They don't set any codes but snapshot data when something "abnormal" happens.

 

Hey, so about a month ago I changed my oil myself, and now the truck is running the best ever. No lag no nothing. Super responsive, almost like you're in sport mode all the time. So happy right now, chirps the tires more frequently now hahha. Also my oil gauge never reads low anymore and all I did was went from ConocoPhillips gas to Sinclair gas which both are top tier. Super happy right now

 

You remembered to put oil back in right? Ha!