Transmission Slipping or something else?

So started to notice last weekend what I thought was my transmission slipping. From a complete stop, starting out I noticed there was some significant delay from the engine rpming (gradual pressing of the gas pedal) up to the power going to the wheels. I then noticed again while merging onto the freeway, at about 3k RPMs the same feeling of delayed power going to the wheels but the engine staying constant.

I had the trans fluid flushed 20k miles ago (truck has 145000 total), but decided to take it in and have it looked at. We flushed it again, and also found a valve cover leak that we also repaired. Drove it home and all was well.

Another thing that I found odd, was before the flush and valve gasket fix the engine was struggling to idle at 450rpms when I first started it, significantly lower idle than it should be.

However, come morning today driving to work I noticed the same symptoms as above. From complete stop to starting out there was a good delay after backing out of my drive and putting it into drive and then again at around 3k rpms whilst getting up to speed.

Thinking back on the weekend, the only times I noticed this 'Slippage' was when I was driving the truck for the first time that day or after a longer period of time when it had cooled off essentially. Now I know, extreme cold may have an impact on gear shifting but I wouldn't think to associate it with the 'slippage' I am experiencing, especially since this mornings temperatures here in SLC were warm. Transmission temp on the way to work never got above 140 (I only have a 15 minute commute), before pulling out of the drive way I let it idle for a minute upon starting the truck just to listen to things, idle was fine (~600+) and shifting between gears was smooth.


Anyone have thoughts?

I have a fuel filter on order but looking for any other ideas. Maintenance has always been on schedule, and like a mentioned this last weekend was the first I have noticed such activity and it has run without issue up until now.


2003 Tacoma 3.4 Auto - only owner

 

This actually sounds a lot like sticking shift solenoids, if you plop it down into 1 with the lever when it's having an episode does the problem go away?

 

Ill have to try shifting it down to L when I noticed it as I pull away from a full stop. The other scenario at the 3k rpm mark I am have only noticed when I am going 30-40mph. Although, if it was a solenoid wouldn't the CEL come on? or A/T Pressure light potentially?


Could you also explain for my sake around why plopping it down to L would potentially make the issue go away? It should essentially already be in 1st gear when just starting out right?

 

Also, worth mentioning I have scanned for codes and nothing pops up.

 

The trans controller is not a genius and it cannot tell when the solenoids are in a position or not, it can only sense if their resistance is correct. And it assumes from trans speed if the shift was successful. If they're in between or stuck it might not report that. 1 and 2 on the lever manually actuate the valves in the valve body, taking the solenoids out of the equation, that will narrow down the issue fast if that solves your problem. My Land cruiser has two sticky solenoids so sometimes it tries to start in 3rd and sometimes it hangs between shifts and has to go and try again, feels like slipping but it is actually going into a low gear for a moment to correct itself. And it never throws a code... I need to put my new solenoids in haha

 

Got it, Ill try to shift to 1 the next time I notice it from stop.

What would your thoughts be on the 3000rpms pulling onto the freeway. Still Solenoids? I would think it wouldn't be trying to figure out the gear needed at that RPM given the amount of gas I am giving it to get up to freeway speed.

If my shift to 1 test works out and that means it is the Solenoids, I could essentially drive it around shifting through the gears manually without fixing it for awhile then? Sounds like that may be what you are doing?


I did pull a CEL back in October coming home from lake powell, I was pushing the truck pretty hard and loaded up. I can't recall for the life of me what the code was, but looking through other threads the P0770 could have been it. I faintly recall it being for the transmission/shifting, but reading at the time it said it was still drive-able so I cleared the code and kept on going and it has never come back since. I have tried going back through my search history but haven't been able to confirm what the exact code it was at the time...

 

lets hope it is a shift solenoid and nothing more. Is there any delay when in reverse when cold?

 

I have not noticed it in reverse yet.


Speaking of the conclusion of temperature, what that make sense for a solenoid to be an issue when it was cooler rather than when the truck was warmed up and running longer?

 

Mine seem to act up whenever they please. More often hot, but cold occasionally too

 

What would your thoughts be on the 3000rpms pulling onto the freeway. Still Solenoids? I would think it wouldn't be trying to figure out the gear needed at that RPM given the amount of gas I am giving it to get up to freeway speed.

If my shift to 1 test works out and that means it is the Solenoids, I could essentially drive it around shifting through the gears manually without fixing it for awhile then? Sounds like that may be what you are doing?

 

The 3000rpm one throws me for a loop, this is gonna be a feel thing that I doubt I can't diagnose from here. Usually a slipping trans will bounce the RPM up a bit when the slip occurs, but not always.

I occasionally shift mine manually to get things working again. It isn't a long term solution. I just haven't had the time to change the solenoids yet. They aren't that hard to change or reach though.

 

Yea, I can understand that. The 3000rpm situation doesn't match up to the typical slippage description to me either. It hardly bounces the rpms, but the lack of power/pull is there. I kinda of more associate it with a slight lack of fuel/air sputter rather than transmission. I have a fuel filter coming in this weekend (to my knowledge its never been changed) and I plan to clean off the MAF again as well so we will see what that does.

In the past I have also had throttle body/TPS issue symptoms where I found a thread comment (below) that with the engine off, pressing the gas pedal fully and releasing it about 100 times helps clears it up, might be time to give that a go again, it worked before.

Threads:
https://www.tacomaworld.com/threads/bad-throttle-lag.163262/
https://www.tacomaworld.com/threads/cant-figure-this-hick-up-out.168680/

Post:

 

an automatic transmission is nothing more than a controlled leak... read the trouble shooting pdf. This is for an A43D auto trans.

 

So, no luck this morning. It is still happening at stop and about the 3k mark. I had a thought last night on the way home, I usually run my truck with ETC engaged as I like the shift pattern per my foot pressure on the gas usually. I decided to turn it off last night on the way home and noticed that given the usual foot pressure I have on the gas pedal it was shifting out of 2nd at about 3k rpms (ETC engaged it is usually 3.5k) and wondered if the 3k issue was it trying to figure out if it was in ETC or not, but this morning proved that point wrong. Food for thought anyways.

From stop this morning, it was so subtle I wasn't able to shift down to L quick enough to test if that got rid of the issue or not. Still waiting for it to happen for a longer period of time for that test.

However, when it started doing it at 3k rpms again, I forced it into 2nd gear and slowed down below 3k to try again and it still 'slipped' around the 3k mark in forced 2nd gear, although I want to say it was less noticeable???


Thanks for the PDF Glamisman, I think I am going to test out the Stall Speed scenario as I notice when I am on the brake in reverse for the first start of the morning the engine seemed to be trying to engage the transmission (RPMs are lower around 450-500 and noticeable noise like it wanted to move) to go even though I am on the brake. If I give it some gas the engine lopes and then idles a bit more normal after that and isn't trying to engage like before. I haven't noticed this in D yet.

Ill continue to test and keep updating for more thoughts and ideas.

Thanks for your input thus far.

 

Just popped codes:

P0300
P0301
P0304

Happened heading home from work when I kicked the gears down to get up a slight grade.

So looks like the issue I was chasing was these misfires and not transmission slippage. Initial look into the engine bay I wasn't able to locate and issues with the wires or vacuum leaks. I pulled the MAF and cleaned it, but no change upon reinstall.

Also, with these misfires I found that my muffler has a leak in it (air is audibly noticeable puffing out of it with these misfires).

Feels kinda odd that these codes wouldn't have shown up earlier given the very noticeable symptoms. Truck is essentially undrivable at this point the misfires are that bad. I was lucky enough to be within a mile from home on back roads when it happened and limped it home.


edit:

Ended up being the Ignition coil for 1/4 cylinders. I swapped it with the 5/2 coil and the codes followed. Ran to the dealership, 130 bucks later and 5 minutes to swap in the new one and its running much better, codes cleared and no sign of showing back up.

Case closed hopefully... for now.

 

That's an interesting chain of events. Thanks for the post!! I have a 2015 Tacoma pre-runner doing the same thing. This started being very noticeable after I changed a knock sensor wire that a rat decided to eat. I had previously noticed it delaying in the morning when I shift from reverse to drive, but that had nothing to do with the knock sensor wire. I thought that maybe I didn't get my intake manifold sealed good and it was sucking air so, I removed it and added RTV and re-installed. No change. Then I thought maybe I damaged an injector or the seals were leaking during the rat repair. Changed all the injectors and seals. No change. I saw online about re-setting the TPS, especially since I had the battery disconnected for the full repair and CEL reset, but the video I watched only said to press the pedal to the floor 3 times. Far from 100. So, obviously that didn't work. Exasperated at this point I went to a mechanic with the high dollar scan tools and for $20 he couldn't find any codes. Told me it was either spark plugs or a coil going bad. I changed the plugs last night doesn't seem to have worked because it still missed a little upon acceleration, but I haven't had it on the interstate yet. That's when I notice it the most. I also notice something is not right when I sometimes crank the engine and it will miss the first turnover then start. I have one coil ordered and will be here Friday. I plan on just swapping one out until I get the bad one. Super easy to change on both sides. I hope this fixes it because I don't know where to go from here. Oh I also cleaned my MAF sensor as well. No change there either. Any suggestions will be greatly appreciated!

 

Yea I was at the exasperated point as well and after talking through it with Speedy on the thread I had chalked it up to being my shift solenoids. I was glad it threw codes finally though as it was always still on the back of my mind, and I would try and provoke it (with possibly risk of more damage) by hard shifting on purpose and driving it hard just to see if I could find any other clues to what the issue may be. Fortunately for me, when it did pop codes I wasn't driving it hard, just hit the skinny pedal a bit more to shift down and get up a hill.

With the way mine was acting though, I would have assumed it would pop the misfire codes much sooner than they did. Even with my changing the bad coil over to 5/2 cylinder it took a good minute of the truck idling like shit ( I even put it in R and D to back it up and move it forward a bit) to trigger the codes again.


The only suggestion that I can think of at the moment is maybe testing your coils ohms cold and hot ( I saw the figures somewhere during my research). I don't know if it would have made a difference in my case if I tried that before I got codes or not.

Does yours only do it when its "cold" initially started for the day, or can you recreate the issue always?

I was only able to notice when it was cold. After running the truck for a bit I could never recreate it until the next day.

 

I checked the ohms of the coils as I had them out to change the plugs. They all showed good continuity, however the engine was cold. Mine usually does it on the interstate when holding a steady 75 or 80 engine hot. It'll struggle on slight grades then drop into a lower gear. It feels just like when you're behind an 18 wheeler and the draft kicks you a little bit. So........I bought one coil from Rock Auto and decided to put it in one of the drivers side locations. I threw my tools (10mm and 12mm socket for the bracket that's in the way) in the back floorboard along with the replaced coil and headed towards the interstate. Drove it up to a rest stop near me and swapped it to another location. Drove it back to the QT and switched it to the last location on that side and it seemed to respond much better. I may have a glitchy one on the other side so I decided to order 3 more. They're not very expensive at Rock Auto so what the hell. I've already thrown plugs and injectors at it. I do believe that I'm chasing the right rabbit this time. I can tell a difference with the one coil replaced. I'll replace the entire right side when the other three come in. Damn electronic cars. Whatever happened to a basic combustion engine and 4 bald tires?

 

Well hopefully you have it figured out!


Myself, I noticed a small hiccup this morning pull out of my drive way when I initially switched into D. It felt more like my first issue (my #12 post), which I have had come back yearly it seems when it gets warmer, but another 100 pumps of the skinny pedal usually resolves it for the year. Hoping that is all it is this time as well.

I too plan to order up another 2 coils from camelbacktoyota as they are only $88 a piece there, where-as my locally sourced one from the stealership was $130 out the door. I can almost get 2 for that price and free shipping from camelbacktoyota...and then that way I have a 2 spares just in case it happens again when I am not less than a mile from home... 1st gens have 1 coil : 2 cylinders. Sounds like your 2nd gen is 1:1 ration of coils/cylinders.

 

Yes, that is correct. 1:1 ratio for mine. I got my coils from Rockauto.com for $13.00 each. GEN 1's are about $18.00 there. They seem to have really good prices because they skip the brick and mortar. I have never had any issues with their products either. Mine seems to be doing great right now. I will still install the other three coils since I have them. It still acts a little funny upon startup sometimes but runs and drives fine. I guessing I have one more coil that's always late for work. He can easily be replaced.