2009 Toyota Corolla Acceleration Issue

Hello all!

I am having issues with my 2009 Toyota Corolla. I have ~110k miles on it, and I am the 2nd owner. I am not educated on cars whatsoever, so please excuse me muddling through this.

Back in August, my car started having some issues. I noticed the check engine light would come on at random times while I was driving. When this check engine light came on, I noted that my car sort of stuttered a little. For example, I would be driving down the highway at ~60 mph, and my car would suddenly slow down just a bit. I was able to bring it back up to speed quickly though. This happened a few more times randomly throughout the next few months.

In late November/December, however, this issue got worse. I would be driving my car, and the check engine light would come on, and my car would slow down, and continue to slow down. I would be bumbling down the road at ~25 mph with my car not responding to the gas pedal. This issue would happen at any time, too. It would happen 10 minutes or 30 minutes into my drive. It would happen if I were taking city streets the entire time or if I were on the highway. I took it into a repair shop, and they read the code, and said they couldn’t find the issue/replicate the problem. I took it into the Toyota dealership to get them to check it out. I cannot remember what the code was (I will update this post after I talk to the dealership Monday), but they ended up replacing all my spark plugs and coils. This occurred in December. I thought the issue was fixed, but it was not.

Last week, my car started doing the same thing. I would be driving to work, and suddenly my car would stop accelerating. I mainly drive highway miles to work, as I work ~30 miles from my job. For example, I would be driving ~60 miles an hour on the highway. My car would stop accelerating, and slowly, but surely, my car would slow down. I would be able to maintain it ~40 mph; however, if traffic was to slow down, my car would not be able to speed back up to 40 mph again. It could only get up to ~20 mph. I would be pressing as hard as I could on the gas pedal, and nothing happened. Occasionally and sporadically, the RPMs would shoot up and I would get a burst of energy. This was short lived though, and my car would go back to ~20 mph. Eventually my car would get out of this “funk”. This issue lasted anywhere from 5 to 20 minutes. This happens every time I drive the car too.

I took it to autozone earlier this week to get the code read, and it said “Ignition Coil A Primary/Secondary Circuit”. I called my dad, who is pretty educated on cars, and he suggested getting a fuel injector cleaner. I did that, and the issue is still happening.

I am incredibly fed up with this issue. I have already put ~$400 into this issue, and it is still not solved. I want to fix it the right way this time and not feel like I’m throwing away my money. Please, please help me here. I am at my wit’s end, and I do not want to have to buy a new car! Thank you in advance.


Your vehicle has a drive-by-wire throttle system.

What this means is, instead of having a throttle cable from the throttle pedal to the throttle body, your vehicle has a throttle pedal position sensor that sends a signal to the computer, and from that signal, the computer operates the electronic throttle body.

This is the system that you want checked out.


Awesome. I will do that.

I should probably also mention that when I am idled at a stoplight and this issue happens, my car seems to rumble. When my car is running smoothly, the engine runs at a steady purr. When it is doing this, though, it seems to rumble. I’m sorry, I don’t know of a better word to describe this. Thanks in advance again!

i also have a 2009 corolla. The symptom you describe is exactly what happened to me when my coils failed. Coil a is the coil for cylinder number 1. Facing the engine, it is on the left. It is not difficult to change it yourself.

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They may have replaced one ignition coil but not all of them for $400.

If you had returned the next day with the same problem they might have waved the labor charge but it sounds like there weren’t any problems for 4 months.

You have an ignition coil failure code for cylinder #1 so that is where the problem is, it in not unusual for these coils to fail.

You may have more than one problem but if you are getting a code for cyl 1 coil circuit failure, that has to be addressed first. The engine just won’t run well if all the coils aren’t working correctly.

It sounds like a faulty coil but you said they already changed them . Hopefully they didnt screw you over and tell you they replaced them and didn’t . I wouldnt take it back to that same dealer , take it to an independaNT and have them check the coils and plugs and see if they think they were brand new coils and plugs . also you said in original note it would slow down , that is the computer putting in limp mode so as to not destroy the engine and is probably normal but I don’t know this car specifically .Also you will never have all of the coils go bad at once , At most you will have 1 or in case of very bad luck two so why they would add another $100 to bill to do all four is beyond me . Oh wait yeah profit on their part .

DIY approach you can afford to replace them as they fail. I’ve done it like that… forever. I’ve never had all of them fail but have had several fail over the course of time. A professional repair shop does not want to have an unhappy customer returning over and over again as each coil fails in succession. Some coils are quite expensive but most are reasonably priced. It’s the labor that costs the most. So it is better all the way around from a professional standpoint to just change all of them and avoid callbacks and unhappy customers that are paying more in the long run. Plus, have you priced kits with all of the coils? Like most things, they cost a little less in quantity so a little bit more savings to ice the cake…

The OP didn’t pay for new coils, these coils are $110 each so for $400 they would have only replaced one coil.

You should get the problem to surface when the code/scanner is attached to the diagnostic port. Then live data stream can be accessed. I don’t know if there is a scanner that can record live data that can be brought back to the shop, where they can read the data back, hopefully determining a path to follow.

If you are willing to change parts in search for the solution, you might have them replace the ignition module, also called the ignitor. Sorry to say, my research shows the ignitors may be in the ECM, Engine Control Module, which would require replacing that ($$).