Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

2014 Scion tC starting to hesitate under acceleration

So far I have only noticed the problem in first gear (it’s a manua transmission), only when the engine is cold, and under heavy acceleration, but it has happened a couple of times recently. There are no engine lights coming on. The car has almost 90K miles, but I just purchased it recently.

It looks like 2 of the coil packs have been replaced, because they look newer than the other 2. I could try changing out the spark plugs, but other than that I would like to be able to troubleshoot the car to avoid replacing parts that I don’t need. I can take it to a mechanic, but I would like to learn how to do more things myself, especially since I’m going to be driving older cars (for financial reasons). lol

Without a CEL everything is probably okay.
The plugs might be due for a change, wouldn’t hurt.
Check air filter and other routine maintenance items.
Run a bottle of fuel system cleaner such as SeaFoam through it.

I don’t think you really have a problem. Just with colder weather everywhere, even down here in rainy Florida, you just need to be a little more gentle with the accelerator pedal until the temperature gauge starts to move.


Best not to do that, even if finances are not a factor for you.

Any other changes made to it? Does it have factory-specified plugs? What’s their condition?

1 Like

Yes, maybe I should be more careful. When I said “cold” I normally let it idle a couple of minutes while I’m looking at navigation and music, but that’s probably not enough. I don’t have a temperature gauge. But there is a little green light that shows cold. I guess I should drive it gently until that light goes off? I haven’t looked at the plugs yet. I only noticed 2 of the coil packs look newer, but I didn’t remove anything yet.

It’s better to skip the 1-2 minutes idling. Start it and drive gently for the first minute or so.

Anything else, besides the 2 coil packs, been changed from factory original? What about maintenance/mods done by previous owners?

1 Like

Well, I bought it from a dealer, so the only records I have is what’s on the car fax. I can look again, but it didn’t show much. It doesn’t look like there are any modifications on inspection (such as a cold air intake). So I looked at the CarFax again, and the last maintenance inspection was in March of 2017, and it only had 38K miles. After that, the only record is that the transmission fluid was changed at 77K miles.

Kevin you’re doing fine. I do the same thing, start the car. Then do the windows. If necessary set up the navigation. But even then it takes about a half a mile for the temperature gauge to come off the peg. Yours only has a light, so just be gentle until the “cold” light goes out.


These are the common causes of hesitation during rapid acceleration, in no particular order

  • fuel pump
  • catalytic converter or other exhaust system restriction
  • egr
  • fuel filter
  • engine air filter
  • air/fuel mixture problem
  • basic ignition system & tune-up stuff (verify timing, spark plugs etc)
  • compression

W/no codes what I’d do first is a scan tool fuel trim measurement. Afterthat I’d probably do a fuel pressure test.

1 Like

If hard acceleration in first gear results in any wheel spin the traction control nanny will disable the throttle for a moment, this results in a moment of coast when you want to accelerate. If the road is clean switch off the traction control and see if the problem goes away.

1 Like

Thanks I didn’t even think of this. Doesn’t the traction control light come on though? I’ve seen it come on in the Kia and heard the noise. The scion has that light but it didn’t come on. I may be wrong but I still think it has something to do with the engine being cold, because that’s the only time I have noticed this.

Check your owners manual. Maybe the light only comes on if a fault is detected, and not under normal operation.

1 Like

I haven’t checked it yet but I think the light is supposed to come on if you’re losing traction. My gf said it happened to her, but she doesn’t have as much experience driving a standard. She also said it was hard for her to drive in the rain and I’ve never had any problems.