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

I might be slow at some things and this might be one of them. I don't get it?

 

Just being goofy, no worries

 

It's all good.

 

I've looked over data from about 25 different drives with the condition happening in several of them.

I've not narrowed down a magic formula but I see a similar delay in throttle response happen in other conditions while moving but it not being noticeable by me.

What I do typically see is that the next sample after pressing the accelerator the Throttle is commanded a little bit then goes back to zero for several samples usually 250 to 750 ms and then responds normally.



What I can say it doesn't look like a lack of response but looks like the ECU is severely limiting power because throughout the delay portion the RPM's rise very slowly.

I think I found that anyone should be able to see the delay by bringing up the "ECO Coach" (Green Eco Bar thingy)

If those that have the lag occur can see if they see a similar behavior on the ECO coach bar where when pressing the accelerator the eco bar doesn't respond then suddenly jumps up to where you would expect. When it behaves normally the eco bar responds exactly in tune with your pedal input, when the problem happens it does not.

The annoying factor is that its seems like you are stuck in a condition and you have to wait for the response to happen and hold the pedal constant otherwise you spin the tires when it finally responds.

 

I've had my 2022 for almost a year now, but apparently didn't notice bad throttle lag until couple weeks ago... Maybe because I wasn't driving too ceazy.

Was pulling out on the main road with cars coming at me from one direction... My truck didn't cooperate and didn't listen to me flooring it and instead decided to take 1-2 seconds break in the middle of the intersection with other cars luckily slamming their breaks to avoid T-boning me...

 

Anyone have a case open with Toyota that has resulted in anything positive? I
Just opened one, now I’m waiting to see if they help.

 

Yes, they've been receptive and opened a TAS case, they reset the TCM memory last month, I just need to give it time and go back when the recall work is due and we'll see what the next steps.

My dealer opened a TAS case, their tech did replicate my issue on a test drive, the current thing though they had them reset the TCM memory. I need to put a little more milage on then bring the data back to them. I'm going to try to time this with the recall work that will be due in Oct instead of making a special trip.

 

That sounds more like the "dead pedal" issue. I think it's important that we call these accurately since they are two very separate issues. The throttle lag is where the vehicle movement trails behind the response of the throttle until about 2500 RPM's and then finally catches up. The power is not at all linear. There's also related surging and lunging.

 

To update this thread that more people might be following. I'm looking into 2 areas right now. First one being how the throttle is being manipulated by the ecu at idle where only a small adjustment needs to be made. My most recent data I wasn't logging all the data I need. One thing I'm looking at if the ECU sends a signal to crack the throttle a tiny bit but the throttle doesn't respond to that small input does it limit things for a period of time. Some of my really old data has the pids I need and it does seem like the throttle is in control. But my recent ones I left out the Duty Cycles and the sensor voltages.

The 2nd Is I'm digging into the Break/EPB Computer which controls VCS/ABS/TRAC. I did note in a test drive that the same dead pedal lag occurred when I had VSC/Trac disabled (Long press and hold of the traction control light)

One interesting thing though is that while the engine ECU can consistently send data every 125ms the other computer monitoring the wheel speed sensors, accelerometers, incline meter etc can only send or updates data every 350ms to up to 650ms. (The update speed varies greatly depending on what data I'm asking for) I wonder if that means if this computer sends any reduce throttle message to the ECU computer it can be a longer time before it realizes that condition changed and sends the OK to the engine ecu.

Its probably going to take several more test drives to gather the new data and see if any of this checks out.

 

This is a clear example of dead pedal event I captured most recently but don't have all the pids. At idle the duty ratio to the Throttle at the time was 17.2% so I subtracted that from the duty ratio pid. We can see that the ECU is commanding more throttle but its not quite moving as shown by the Throttle Sensor or the Throttle Position PID's Had the throttle moved a slight bit here there wouldn't have been a dead pedal feel. I'm missing the actual voltage sensor pid and the close and open duty pids to understand fully how the throttle is being commanded but I think its clear something weird happened here.

 

I can help a little with the sensor timings - thats only the value reporting interval. CAN messages are sent at a much faster rate, in the 10ms range. The communicate on different channels, so the sensor logging/reporting interval and the CAN message rate are unrelated.

 

do you know if you guys are still evaluating this at all, or after the initial TSB is everything just moved on?

 

Thanks that very helpful.

 

There are a couple of TAS cases open but I don't know the status of where those are at. That team is completely separate to mine

 

I'm pretty sure the accelerator position is irrelevant, but its hard to fully test out safely because you never know when initially pressing the pedal how its going to react in many cases I kinda just freeze as you can see with the graphs until it decides to respond. Many times its just not safe to press it further.

The thing I'm trying to figure out if the ECU is deciding to limit throttle intentionally or if the throttle is not responding as expected and the ECU waits to figure it out.

 

I agree with this. I can replicate the lag on my truck on demand now. Slow roll below 4mph… it happens every time regardless of whether my throttle is at 5% or 50%. This is all by feel of course - don’t have real data to back it up.

 

Interesting, I noticed this yesterday, was doing a lane change, where I was just rolling, and needed to punch it to get to speed of the other lane... and it just hung there, for a second or 2... I've felt it before a couple times, but not as noticeably as yesterday.

 

I feel like this figure is a perfect representation of what I'm feeling.

 

I have just gotten the lag overall. 23 non hybrid. My general issue is when I want to accelerate in the range of 0-30 mph I have to really lower the gas to get going. My old 2005 V8 had way better low rpm acceleration and torque. Now if I really drop the pedal everything goes well. So could it be more that the pedal adjustment is such that you need to assume the top 15-20% of pressing the pedal really isn’t where the real acceleration is meant to start? That we need a heavier foot to be ‘normal’?

 

Here is a tale of 2 stops, the 2nd one had lag but not a really long duration. I happened to punch it a little harder because i had a feeling it was going to lag. VSC and TRAC were disabled on this drive to ensure nothing with traction control was the problem. The delay measured was about 375ms, although the throttle ramp up after the delay was also slower.

The thing that seems to be most consistent is the Input shaft speed (NT SPEED SENSOR) being 150 rpm or greater, and the output shaft speed registering 50 rpm. Just after a downshift to 1st gear happened.

However the exact cause of the delay is not known but its probably not presented in the data pids at all but more likely some commination in the background.

The data shows that the ECU appears to be commanding the throttle as told, but I suspect its some sort of signal from the TCU to the ECU that the transmission isn't ready yet, but I have no way to know for sure what's happening. The TCU doesn't provide any data on what's going on really besides the gear selected.

 

This is how I have adapted my driving style... to always apply the throttle gently from one of these stops and rolling stops... so I can feel if it is responding normally or lagging before I give it any more throttle. I have not had one episode of squealing tires or unexpected rapid acceleration. But we really should not have to be dealing with this at all.

 

I have a 23 SR5 and have had issues with the lag from stopped position and rolling stop. It’s very annoying. Almost to the point where I thought about trading in for something else but just doesn’t make sense financially. Dealer did the TSB and it worked for awhile but is back. Mentioned to him that it was back and they did nothing to remedy the situation. I understand that it’s a newer model vehicle and there are growing pains, but this seems like it’s widespread and should have a remedy by now.

 

Hi there, so I've had that same issue. Now that my free oil changes are done I started changing my own. I bought the Kirkland signature oil, a mobile 1 oil filter and I'm going to be honest, this truck is night and day now with the acceleration and the response with the throttle. I also switched brands of had which I only use top tier gas. Been using ConocoPhillips 87, switched too Sinclair cause it was finding better deals with them and truck is running fantastic. Love driving it more and more. Also I don't get the low oil pressure on the gauge at idle. Just under the line at the half way or 12 o clock line. So, I did tell this to my service advisor and he's some what stumped but he feels every oil company's oil is going to be made different. Also he thinks changing brands of gas might have a little to do with it but I've used other brands since I've bought the truck brand new and still had these issue's periodically. He said I should try the other brand of gas for a couple tanks and see how the truck reacts but honestly I don't want too try and I get better deals at Sinclair. So it's a win win for me. One more thing, the pedal feel now is on par with how it feels in sport mode. No lag no hesitation. Just goes and chirps tires. Good luck.

 

Just curious, did you ever have the bad lunge when shifting from park to drive on cold start and did changing that other stuff help with that?

 

Well I let sit for a minimum of 30 seconds or so until the rpms go down, but ya if you start it up cold and out it in drive right away that will happen, let it idle down, let it do its system check.

 

Yeah I let my rpm’s go down as well but if I go straight from park to drive after they settle, it still lunges forward pretty good

 

well that seems isolated to your truck cause I dont get that like you are describing. So if you are out say running errands and you have started and shut down a couple times have you noticed after the initial cold start do you notice the rpms are super low? So for me the first drive of the day after I let the truck sit for a minute shifting into drive is a little rough. My 2018 Tacoma was the same and our highlander is like that as well. I feel these vehicles just have a higher rpm for awhile until everything is warmed up after you been driving for awhile. Not sure if this helps you but if its only after a cold start then I wouldnt worry cause I feel thats how they are designed.

 

Fuel quality could certainly be a factor in lag/delay performance, as the ignition timing is advanced before the ecu adds throttle, but I checked the knock feedback and in my case it wasn't knocking and retarding the timing. In data where I was also monitoring timing, the ECU did advance timing instantly even though it did not add any throttle.

I guess I will try the 30 second idle thing and see if that does anything I tend to start and drive withing 5-10 seconds of starting the truck. I also may try driving with the ECU and TCU in check mode to see if it sets any DTC with the Tighter tolerances of check mode.

As far as logging data, I'm backing off for now until I talk to the dealer again, I have enough data. The only thing I don't have is a drive longer than 15 minutes, I rarely drive more than 10 minutes and the Trans never warms up to full temp in that time. It did always seem though after a long drive the condition doesn't happen.

Pretty consistently the delay happens when you get to 2nd gear or higher then slow down to about 4 mph while depressing the brake pedal causing the Transmission to downshift to 1st gear. If you apply the throttle right after letting off the brake and the output shaft speed is registering 50 rpm, and the Input Shaft (NT) speed is 150 or more RPM, there high correlation of seeing some sort of hesitation like below.

If I had to take a wild guess there is a window for the transmission to complete it shift to signal the ECU that the shift is complete and it can begin to add power again, however this commination isn't available though the P5 CAN bus it seems. Is possible there is a delay in the downshift because the Input shaft speed is higher.

 

Hi there, you're suppose to let most modern vehicles sit for a minimum of 30 seconds or once the rpms start to come down cause thats when the ecu is doing its system checks and whatever else it needs to do but definitely try that. Fuel whys I always use 87 even up here in Denver where you can use the 85 I refuse cause my vehicles dont run that great honestly.
I really do appreciate the effort and loggin in these ecu data. I hope the techs can get this over to toyota engineers. What you just described about being in 2nd gear or higher section was pretty spot on with my issue, I have just gotten use to it cause thats not that concerning since my acceleration has improved. Keep me posted.

 

Intresting enough I had some thoughts about the shifting.

The PID's don't provide exact speeds but they round to the nearest 50 value.

the 1st gear ratio is 4.92 so if the output shaft speed is about 50 rpm in 1st, the input speed should be about 246 rpm.

Most of my delays logged showed the input shaft speed at the time to be 150-200rpm, and that would be closer to the 2nd gear ratio of 3.26 50x3.26 = 163rpm. So it might actually be still in 2nd gear when its reporting 1st gear.

Also not a factor but it can go from 2 to 1 or 3 to 1 when coming to a stop but it hasn't made any difference I've seen delays in both situations.

It isn't the whole picture because I've had lags at 250-300rpm NT speeds too, it seems more that the nt speed has to be under 150 to not lag.