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

So I thought it was more that it was in a higher gear for the higher rpms but not moving that much faster if that makes sense

 

yes it is only present after a cold start. Tends to do the normal rough shift followed by a lunge, but if I’ve been out running around when I start it has fairly low RPMs <1000 and doesn’t do the kick forward when shifting

 

I ordered a more affordable J2534 interface for testing that should work similar to the tatrix openport 2.0. If that works out I will write a guide on how to do your own logging in a new thread. Probably be a week or two.

 

Hi a few updates:

Low cost J2534 adapter dead end. The Cheap Mini VCI cables have 2 issues, the software is really shady, i think because they include a techstream key generator that sets off the virus programs. Even using a air gapped pc though the VCI interface seems to slow to properly work with the new vehicles. Taxtrix Open Port 2.0 is about 10 times faster. For logging stuff like this you really need multiple samples per second.

Narrowing in on some theory's.

I believe the issue is related to a downshift to first gear that happens when slowing down. It seems like the shift is always too early, but regardless it seems to take a lot of time to complete the downshift. There seems to be a window where the shift might be in progress. Its also possible this downshift time improves as the transmission warms up.

What I see in my data:

Downshift 3 -> 1 there is about a 1.2-1.4 second time to complete this shift
Downshift 2 -> 1 there is about a 1.5-1.9 second time to complete this shift

In both cases I say the shift is early, because the NT speed is too low relative to the output shaft speed to match 1st gear 4.92 ratio. It should wait for the output speed to get lower so that it can match the speed better.

Since the 2 to 1 has a much longer time than 3 to 1 for some reason, its more likely to see a big delay doing low speed maneuvers.

I think most users probably won't notice the delay due to cadence. The timing of the downshift isn't something the user will feel or know happened.

Also at least one drive I wound up pressing the accelerator very shortly after the downshift and it looks like from the data, the downshift actually got "cancelled" and there was no lag.



Also in my "tale of two stops" below the stop that had no lag, the accelerator was pressed about 1.7 seconds after the 3-1 downshift occurred, but the one that had a delay the accelerator was pressed about 1.2 seconds after the downshift occurred. Just looking at the graphs is hard to see this subtitle timing thing but when I do the calculations based on the exact sample times i see the difference in timing.

 

Could it be that the throttle lag is caused by the metal shavings debris getting stuck in the oil passages in our dirty engine blocks (from factory) ? And when truck surges forward is when that debris passed through the blockage?

 

Doubtful. The lag is more likely a programming/shifting issue more then anything, based on what I've experienced/read here.

 

In my experiences the surging is simply a byproduct of the accelerator pressed too far due to lack of response. The ECU is completely in control of throttle during shifts not the accelerator, as to why these downshifts seem to take a lot of time is unknown. I don't know if its too early or too late or if the transmission is waiting for the input and output speeds to align before shifting. Unfortunately exact shift logic is not available via the TCU or ECU data streams.

This could be the explanation of why tow haul mode specifically feels better. I think tow haul (especially tow+) locks out skipping gears which would eliminate the more common but shorter 3-1 lag.

Next drives I will focus more on the downshift timing as previously I did not look for that but was focusing on input/output speeds.

How thread the needle this is, I do the logs on the exact same drive every week and some weeks I never experience a 2-1 downshift because I was driving a bit faster, or had to make complete stops or waited the .2 more seconds before pressing the pedal.

 

Got it to do the short delay 3 times in a row by watching for the downshift, but my reaction time was really slow still something like a full second before I press the accelerator due to trying to look at the laptop and drive at the same time. As far as the "long" delay it might have to be a really specific speed (Input/output/vehicle) to make that happen. I was not able to match those exact speeds where the long one happened on a previous drive.

So it may be possible to replicate on demand if you have shift status in front of your face.

 

can you get that to toyota somehow?

 

Not directly, but I can get the TAS Case updated when I go back for service but I didn't want to run down just for this and I'm trying to line it up with other work (key fob+recall) work.

 

I'm probably going to back off logging a lot now as I have what I feel is a good formula for causing the condition. I did inquire about how many miles a TCU relearn should go and I got back 3k miles. Right now there isn't much value going back in with less than 500 miles in, although I can say the last time i had a really bad dead pedal was back on Sept 9th and haven't had a bad one since. I'm going to scheduled a re-visit in November when They can take care of the keyfob and fuel line thing in one trip.

While I'm not sure if everyone dead pedal issue is the same, but I can conclude right now mine is related to the downshift that happens just before coming to a stop.

I also did a few tests with tow haul, specifically tow+ does step 3-2-1 and also seems to wait until almost a dead stop before shifting to 1st.

For avoidance you can also try S1 if you are in a situation were you want to do stop and go below 12mpth. Also waiting about a split second more before applying the throttle at rolling stops does seem to avoid the issue a lot.

 

Chiming in here. Just bought a 2024 Tundra TRD Pro Hybrid yesterday with 4 miles on it (coming from a late model V8). Everything was amazing, then I hit 40 miles and all of the sudden its extremely boggy, like it's not getting enough gas, or in too high of a gear. I will barely go up the hill to my house unless I slam the pedal (which causes surge)

I do also recall driving away from the dealership and getting on the highway and had an unexpected surge when at speed (guessing that's due to pressing the pedal down when not getting the response I expected).

I read about these issues before I got the truck, so admittedly I was looking for it. My wife agrees something is really off tho. It's sad because we got this truck for the safety features, and I don't want her to feel unsafe / regret getting this truck. I dread experiencing the lag many are describing when pulling into an intersection. Half tempted to list it for sale and get the $10k-$15k I could get over retail

I messaged my salesman this morning to see if any TSB updates are available, but guessing I would need escalate the issue to go plug the truck in?

 

It's quite likely. The finance guy at the dealership also mentioned it. He said he couldn't get another one for 6 months out.

 

You can't walk into that dealership and get one on the spot. I could sell this privately to someone willing to pay 10-15k over retail to get it on the spot.

 

Looks like youtuber TRD JON is having the issue with his 2023 platinum we'll see if he has any progress with the dealership.

https://www.youtube.com/watch?v=CYbLQdgQx9Y

 

I have the same crunching sound on the back of my driver and passenger seats. I hate it but I think its due to the cooling seats. I also dont have air blowing from the back. Only the bottom.

 

This is what works for me through trial and error; When engine is cold, starting in 1st gear I manually shift to 3rd gear then switch to auto, no lag, I also disable the auto/stop from the advice of others here, at stop lights or when I need to do a fast lane change, I use either the tow/haul or sport mode ya it's annoying to have to do that.

 

I don't follow those cars, but I noticed NTHSA complaints is littered with lag/dead pedal complaints for 23 highlander.

 

I'm so thankful my June '23 build doesn't have any throttle hesitations whatsoever, at least not in 6K miles. When I hit the skinny pedal, it goes, under all driving conditions. I hope Toyota finds a fix for you guys who aren't so lucky.

Matt

 

I drove new highlander hybrid for 3 weeks while my truck was in the body shop.

Acceleration on hybrid highlander is just butter smooth, electric motor makes it super zippy from the start.

 

I read though some of the highlander threads, a lot of people said things were better after using 91 octane. I didn't log knock and timing pids on all my drives, but some of them i had the data there was some knock and retard shortly after the pedal was pressed, but it wasn't consistent. However it is one of the ancillary things that can cause power to be backed off initially.

 

it’s interesting to see you say that. I just got a non-hybrid limited, and after purchase the dealer put 87 in it. I got the lag at start. Drove 200 miles, put 91 in it, no lag from start for me.

 

Yeah I haven't had any data suggesting that fuel was a common issue. The root problem seems to be around that downshift to 1st timing, but things like octane, drive mode etc, seem to have a side effect of making it feel better or worse to the driver. I did find some correlation to knock/retard being possible cause of hesitation while moving (not in a rolling stop situation).

Seems like Toyota can do a lot of refinement. The fact its happening on other platforms suggests some common logic error or similar programming.

Personally for whatever reason I haven't experienced any bad lag (>.5 seconds of dead pedal) in 3 months, and not many events of small delay (although I am primary driving in a way that avoids/lessons that condition) Last month I looked at scan data and was able to replicate some delays by watching for the downshift timing and that does seem consistent, but the shorter lag time. I have not been able to replicate the long dead pedal delay. There is some hope that only happens in the learning process but without confirmation its always possible it crops up again.

 

Since you can reproduce the throttle lag consistently, could you share the exact steps with us so we can try that?

I'd love to open a tac case with Toyota but no way I'll be able to reproduce it for my dealer...

 

Thx, I'll try that

 

I’ve had the lag for months. Had the computer flash update and that helped short term. I can reproduce it as well. I believe confidently that it is the computer searching for the right gear if you roll through a stop. Come to a complete stop and it starts out fine. To deal with it I simply push the gas lightly and wait a little bit for it to engage…then we are off!

 

I had this happen this weekend, while towing my boat. Not good. Was at an intersection, trying to take off.

 

in tow haul mode?

 

I have a 2022 limited. The hesitation is real, and the frustration with Toyota is growing. I’ve had the dealership tell me they’ve replicated the issue but nothing they can do as toyota Canada has no fix. Feeling helpless and frustrated for almost a 70k truck that my wife is too scared to drive due to so many close calls with hesitation and dead peddle.

 

Lol this thread still going