2011 Toyota Corolla engine concern

Maintenance/Repairs
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1

Hello, all! I’m a college student who bought his first car about a year and a half ago. Got a 2011 Toyota Corolla with a little over 90k miles. I’ve since hit 97k.

I’ve been having some issues with my engine and at this point I’m a little desperate to fix the problem, because I get super anxious about making sure my car stays in good shape.

THE SITUATION:
My car began what I can only describe as “running rough” late last year. Basically, any time I’m in drive or reverse, the engine starts rumbling just a little bit more than usual. This problem ends as soon as I go above 10mph. It only occurs below that or when I’m stopped.

Early this year (around March) my engine suddenly started misfiring. As it turns out, the car has a lot of original parts still in it because the last person didn’t take care of it too well. The issue I got repaired turned out to be the ignition coil on cylinder 1 messing up and causing a misfire. Soon after I got this fixed, I also replaced all four spark plugs.

Then, about 2 weeks ago, the same exact situation happened again. The car would run harder and harder at low speeds, until eventually it would start misfiring. It even did the thing where the headlights would pulse with every misfire. I take it back to the repair shop and it turns out it was ignition coil 1 messing up again. Got that repaired.

My question is: what do I do to stop the “running rough” situation? What could be causing that? I plan on replacing the rest of my ignition coils in the future, but I’m not sure if that would help or not.

Any help would be greatly appreciated. I’ll gladly give more information if it’s needed.

2

I suppose you didn’t go to the dealer and they put in an aftermarket coil…right? Toyotas are allergic to anything that is not made by DENSO and this is why your car is behaving that way. Next time,make sure your mechanic uses the oem part(DENSO)

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Okay, that makes a lot of sense thinking about it. Do you think I’d need to replace my spark plugs too then?

4

The spark plugs are to be replaced every 120,000 miles.

Replacing the engine mounts might be necessary to eliminate that idle discomfort.

5

Runs rough, misfire? You saw flashing cel light on dash?

6

As far as the spark plugs, if they are the exactly the same as OEM plugs specified they should be fine, if the shop substituted a different plug then change them.

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I’m of the school that believes the first step should be a compression check to make sure the engine’s top end is good. It’s stated that the car was not taken care of too well. Verify the engine is half decent before spending money is my premise.
A precursor to a compression check could be connecting a vacuum gauge. That is quick, cheap, easy, and insightful.

If the engine is dropping compression on a cylinder that can cause the spark plug to fail. That in turn can cause the coil to fail. Replacing plugs and coils in a dropping cylinder can be an exercise in futility. Hopefully that is not the case.