Showing/logging low RPM stumble?

On Monday I have a fourth appt w/ my local dealership to look into the low RPM stumble that my '18 has had since new. At my 5,000 mile service , the stumble was confirmed by a tech but deemed normal. At the 10,000 mile service, they "couldn't replicate the customer's concern". Last Monday, they confirmed the stumble again, opened a case with Toyota and at 17,xxx miles I ended up with a new radiator, transmission lines and a remanufactured trans after a glycol test revealed the trans fluid was contaminated with coolant. Immediately upon picking up the truck I noticed the stumble again and reported it to my dealer the next business day.

Based on what the service manager has told me, the dealer tech isn't sure where to go with this. So another case is going to be open with Toyota...and I'm sure that will involve an exchange of information between Toyota and the service dept. That got me wondering if there was anything I could provide to help w/ the troubleshooting.

I have a bluetooth OBDII adapter and the Torque Pro app. I'm not very familiar with the app yet as I initially got the free version to check/clear codes in my old Jeep and then ponied up for the paid version to try and check the calibration ID on the Taco. So, is anyone familiar enough with the workings of the factory tune to say whether or not any of the Torque Pro displays will show what is going on when the stumble occurs? I think I've watched throttle position and timing advance before, but don't recall if anything stood out.

If Torque can't provide the info, is there another app that will?

Thanks.

 

I'm curious about this as well. I'm also getting a low RPM rumble when driving around.

Took it to the dealer, it was documented and was told to give it about 5-10,000 miles for it to sort itself out. I have another service coming up due, so I'll let them know again.

 

I have the OBD Fusion app with a VePeak bluetooth adapter, and was also wondering if there is a way to capture the stumble.

 

Certainly, that is what the log function is for:

https://obdsoftware.desk.com/customer/en/portal/articles/2910194-configuring-logging

You will need to setup the log to track and store the desired PIDs

 

I'd say let the dealer and Toyota deal with it. Don't, in any way, give them an excuse to say you screwed something up by "trying to fix/diagnose it yourself".
Sounds like they are taking you seriously so let them do it.

G.

 

Following....I’ve noticed it in my 18 as well and just kind of over looked it until now. Currently sitting at the dealership now so I’ll have them look at mine as well.

 

Following, my 18 does this all the time.

 

That's a good point.

 

Have you tried running premium to see if it goes away - if not, I'd suggest you run out your tank of regular, pump some 91 or 93 depending on where you live (top tier). Mine always does the slight miss / stumble feeling if I use regular gas. As a result I've used nothing but premium for the last 18 months or so of ownership... engine runs smoother as well. Don't believe the bullshit many will say that premium makes no difference in these trucks. It does. Not true on all vehicles for sure, but this engine LOVES premium fuel...

 

I tried it once and honestly don't remember the result.

Page 635 of the owners manual says 87 is fine...so the truck should run correctly on regular gas. It doesn't matter which brand I use or which station I get it from, it stumbles on every tank. So I'm just doing what the manual says and consulting my Toyota dealer.

 

Smart... my truck performs NO differently on various octane fuels. Just note that Toyota recommends using TopTier brands only.

 

I get it, and I'm not denying that your truck SHOULD run just fine on regular gas. It's a midsized pickup, not a sports car... however, many have reported symptoms such as these disappearing with premium fuel myself included. OVTune also has eradicated this issue for several folks

 

My truck does not have the stumble issue, and I have never run anything but 87 from "where-ever" with no issues.

Just over 55k on mine.

G.

 

Nothing overly positive to report after this morning's appt. My usual service manager called out sick so another one picked up the appt.

Probably not the best decision on my part but I showed up with my "miles to empty" display saying 18. I had debated getting gas on my way there, but I was running late and the truck sometimes runs better immediately after I get gas. So I didn't want to take the chance on it not stumbling for my road test with the tech. So as soon as I arrive, the service mgr comments about the low fuel and says they won't be able to do a very long test drive. I got a bad feeling from that.

Now it had been my understanding that I was supposed to show up at my appt. time and would immediately be paired up with the tech who did the transmission work so we could go for a drive. This didn't happen. They sent the truck back to the shop to be looked over while I spent the next hour in the waiting room. When I asked for a status I was told the tech had already driven it and couldn't duplicate the symptoms. The truck was then brought back up from the shop and the tech and I went for a very short drive since the display now read only 5 miles to empty. The tech did ask me what octane I run and where I get it from. I told him I use regular and have gotten is from a number of different stations in the area and it behaves the same way every time. He asked that I run high test on the next tank. I was already frustrated at that point so I prematurely got into the "I shouldn't have to run high test" mode.

Anyway, I got it to stumble a little, but the tech seemed to think it was bumps in the road. I didn't agree but that's a hard point to argue. We returned to the dealership and I was asked to go get a few more gallons of gas so more testing could be done. I suggested the tech go with me so we could go right into more road testing but they refused. The gas station was only right down the road so I headed there, grabbed 5 gallons and went right back. By the time I got back the tech had returned to the shop. I was told a second case had been opened with Toyota but they needed to check the trans temp before submitting, so after some pushing I was given a loaner and left the truck there. No second road test occurred.

I apologized to the service manager for being irritated and he said he understood my frustration, but that wasn't the vibe I got from him or the tech earlier in the visit. I'm supposed to get a call back later today with more info.

 

The update I got yesterday was that the tech was unable to speak with Toyota. He supposedly made two attempts and got off the line after being on hold for 30 minutes during one of them.

I called back this morning to tell them I was more than willing to do another road test with the tech. At first the service manager told me he didn't think the tech had gotten a hold of Toyota yet, but later in the conversation he said that maybe they had given him some additional steps to take. He also mentioned that the trans fluid level was checked and determined to be correct. Sounds like they are doing what they can.

 

Any new updates? My truck does this as well. It has done it since the week I bought it. I'm only at around 2000 miles right now.

 

Me too. 18 dclb Trd sport 4x4

 

If you read the OVtune blog when Matt updated to 1.05 I believe it gave a good overview of how this engine runs/programmed. What your feeling is most likely a "misfire" but for what ever reason it is not enough to trigger the check engine light. Pairing a high compression engine with lean running on 87 octane will create this issue even if Toyota says 87 is fine. I can feel it if let say driving up a gradual incline at 35-45 mph with slight throttle application. I have tried 91 octane & noticed it less frequent for sure.

The other thing it could be is torque converter shutter. The torque converter staying locked too long & creating a shutter/stumble feeling. This is Toyota trying to eek out MPG as much as possible. Lots of things involved here. Acura had a horrible issue with this back in the 2000's on TL's & MDX's. They would stay locked way to long & kill the torque converter to the point were it would feel like running over rumble strips. It really boils down to Toyota's poor software programming for the engine/trans.

 

Torque converter (TC) shudder - going into the loop: partially locked-fully locked status, causing a slippage and bumpy road feeling. TC temperature is rising a bit
Usually happens under low RPMs, high engine load and tranny stuck in 4,5,6 gears with TC in above status.
See OV tune thread for more details, we are waiting on the fix release any hour now.
Tech is kinda correct, this is "normal". Dealer wont help you, except "reporting".
Force downshift to deal with it.

 

Makes sense, I did try a full tank of 93, nothing changed.