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Hard Shifts With 2010 Auto Transmission

by listoff, April 17, 2017 in Toyota Corolla (2009 until 2018-19 “TNGA”)

Hello everyone! It's been a long time since I've been on, but I have an issue that's kind of stumping me.

It's a 2010 Corolla S, automatic, with 130,000 miles and been in a semi-major front end accident a few years ago and repaired.

A few years back, I came to the forum asking about hard shifts. It was recommended that I perform a few drain and fill style ATF changes. I did four or five of those over the span of 30,000 miles so I could cycle out as much old fluid as I could without doing a flush. The shifting seemed to get better so I chalked it up to a success and went on with life. Over the last year, I've noticed the rough shifting coming back little at a time. Recently, it's become quite noticeable and actually starting to concern me. From a stop and accelerating from 1st, 2nd, 3rd, and OD, all is well and no issues. The issue is with downshifts from OD to 3rd or 2nd, especially when I need to pass someone. I will give a decent amount of throttle and it drops out of overdrive and waits... Then shifts into second. Almost like it missed third gear altogether and went to second. On the times it does find third, it lands into gear pretty hard and you can feel it jerk into gear. The concern is not only that something is wrong, but it's also starting to cause a safety issue. I'm not an overly aggressive driver, but if I see an opening in heavy traffic, I'll punch it to merge in. I've had the downshift hesitate long enough that the spot in traffic that I was clear to enter without any issues now has traffic bearing down on me with quickly and I'm stuck with puny acceleration until the car wakes up and downshifts.

This issue isn't constant and I can't always recreate it. Some days it drives like a brand new car and other days it seems like it's time to trade her in. I checked my ATF this morning and I noticed that it was a little past the full mark when hot, so it could be overfilled, but not by a whole lot. I also noticed that it wasn't shiny red on my rag when I checked it. Not brown, but more of a maroon color and did not smell burnt. I could drain a little, but I'm not sure that will make a difference.

I will mention that I'm running the original spark plugs. That seems like a random comment and I know I'm way overdue on changing them... But I started to think that maybe a general lack of power due to old plugs is causing an issue where the transmission is making up for the loss by shifting me back an extra gear when in normal conditions it wouldn't do that?. I'm honestly not sure. Any thoughts or suggestions would be welcome. Thank you!


Unless the ATF fluid is way past the upper mark on the dipstick - I wouldn't worry too much about it until the next time you change the fluid. Darker maroon color, but doesn't smell burnt, means that oil is just a bit dirty - mine gets that after a few thousand miles after an oil change. Not much concern, right now, that just means that the oil is doing its job - keeping the particulates suspended. If you see a metallic sheen on the rag/paper towel, after wiping the dipstick - might think of dropping the pan next time and seeing what it looks like there. It is perfectly normal to get some metal slurry during normal operating - material is being abraded from the discs inside the transaxle. Initially, it can be pretty excessive - but after a few oil changes, should start to wear much less than before.

Couldn't hurt to swap out the plugs. Misfiring could cause the car to pull spark, timing - which "could" cause the car to not shift as smoothly as it should (timing already retarded due to misfiring, so the ECM can't retard it as much during a shift, making it feel like a hard shift).

Sort of a long shot - but I've seen weirder stuff happen, especially with normal maintenance items. I usually try to get them done first - just to rule that out.

Which type of ATF did you use, exactly? Allow enough fluid out to correct the overfill, as it would read even higher at transmission's maximum possible operating temperature... It would be advisable to remove the pan to clean it and the magnet, and replace the filter. You can then replace all of remaining fluid by disconnecting cooler return line, and idling it a quart or two out at a time.

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DENSO 4711 Iridium Long-Life; Iridium TT spark plugs,2010,corolla,1.8l+l4,1444173,ignition,spark+plug,7212

Hi guys - sorry it's taken me so long to get back. I have used the Toyota WS fluid purchased straight from the dealer's parts counter. I have to slide under soon for an oil change anyway, I'll let out a tad then. I'll give the spark plugs a shot too. Thank you for the replies!

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