Engine Revs, But No Engagement With Transmission

I've pored over many TW transmission threads and didn't find this issue, but possibly somehow missed it in all the discussions. I have a '17 Sport with an automatic transmission.

A very few times when starting from a stop or a low speed, I'll attempt to accelerate and the engine will rev to over 3K RPM's, but there is seemingly no engagement with the transmission. Then the transmission will engage, the RPM's will fall back to normal for that speed and everything is fine. This has happened perhaps 3 or 4 times in the past month and I can't recall any commonalities to its occurrence except that I was accelerating from a stop or low speed. I cannot replicate it on demand, so suspect that a Toyota service tech will also not be able to replicate it.

Could this result from low transmission fluid? If not that, what else might be going on? I also have an occasional clunky downshift when coasting into a stop from a low speed.

My 15K service is due and I will call it to the attention of the service rep when I take it in. Any advice on how to describe this issue when I take the truck in, so it gets taken care of?

 

I've got 38k on my SR5 and occasionally, in a morning cold start, my transmission takes a little longer to engage before pulling away. (I plan to flush the transmission this summer) However, it definitely does not get to 3000. I'd recommend you take it to the dealer.

Try to document it with a video on your phone. Be safe.

 

Harry: I don't believe that this is correlated with a cold engine / cold start. Unfortunately its seeming random occurrence doesn't make an attempt to video it feasible. Thanks for your input.

I can see how this could be a safety concern when you don't get the vehicle engaged and moving forward under power when you expect it to.

I'm not a "car guy" nor am I knowledgeable about how engines and transmissions work together, so I want to get the language / description right when I take it into the dealer.

 

Maybe low transmission fluid.

 

Mine will do this very rarely only when the truck is rolling from an idle. Example being if I'm at a stop light headed down hill. It's done it twice.
It's definitely not a cold start issue in my case.

 

I'd keep your terminology very simple with them. (The last thing a mechanic or shop guy wants to hear is some professed non-"car guy" trying to sound knowledgeable.)

I'd just say something like, "I've noticed that my truck will periodically not shift into gear until it reaches high rpm's. I'm very concerned. Could you please check the automatic transmission fluid to make sure its at a safe level?".

That'll give them enough to go on to find the root cause.

 

I can reproduce this leaving the office parking lot, which is somewhat downhill. Imagine coasting/rolling at 5-10 mph, no gas applied. Then I start to apply gas and the engine revs to the appropriate level then engages the transmission (might be deciding to go into second). If it does engage as soon as I start on the gas, I would imagine it would slam into gear and potentially slow the truck down hard.

This can also happen as I leave my neighborhood coasting at the same speed, but I have to try and make it do it most times. My transmission fluid was already checked and filled to spec

 

This is exactly how mine does it.

 

mine does the exact same thing in the situation you describe, like it is neutral for a split second.

 

Sounds like the computer is slow to engage the transmission when the accelerator is pressed. Almost like it’s confused.

 

Yeah same here. The more I think about it the more I realize that I have just learned to throttle through these types of situations over time. (instead of coasting)

 

Mine will do it when it's first started and I don't let it warm up

 

Me thinks it is ECU programming. It may also be related to the downhill control built into these little computer brains along with throttle by wire. The Tacoma I had did this too, but I learned to ignore it or just roll with a little more throttle instead of just coasting.

 

Mine used to do this as well......but only when hard accelerating while turning...... I thought it was low tranny fluid.
The fluid being low, the tranny could not pick up fluid during a hard accel and turn.....IE: the fluid was being pushed away from the tranny pick-up....l

I filed her up....was 1 1/2 liters low..........all good now accelerates like a cut cat..!! No hesitation.

 

If I had to guess, I'd say the throttle position sensor is intermittent/defective ... or maybe the connector to the sensor is intermittent. Since the tranny doesn't suddenly slam into gear with a jolt, I believe the drive by wire system is not getting the proper signal info to engage the transmission. This is something you should definitely have the dealer check out.

- JAMES

 

Certainly could be.

Exactly as you described it here, and your concern that it's random enough that it may not be replicated easily. Then ask for them to do a full check of the fluid level, not the abbreviated check.

Unless you have a real jerk of a shop, they should accommodate that, although it will take more time as the vehicle will have to be cool before they start. They may even want to keep it over night.

As others suggest, certainly other things could be happening. But you can only eliminate one thing at a time, and it's reasonable to start with fluid.

 

Made this for you. When I say “now” the transmission is in gear....I am thinking second gear honestly.

https://youtu.be/DSsO6kwcpHc

 

I'd ask the dealer to do a stall test.

 

My 16 did the same thing, rolling up to a corner, off the gas to check traffic, then apply throttle to go. Engine revs up, slams into gear. Dealer said transmission was normal.

Now I drive a 16 4Runner. It has a decent transmission.

 

Can you replicate in ECT mode?