Ignition Coils - Frequent Recommendation to Replace

Hi! Years of lurking, first time posting.

I have a 2014 Prius II. Put on 70k miles in my 4 years of owning. 140k now. Religious oil changes when the light comes on since owning it.

In Dec 2020 (probably 115k miles) My engine light came on - and stuttering, shaking - immediately brought in to shop, had 4 coils and spark plugs replaced.
Put on 8~10?k miles and in Oct 2021 the same issue happened. Brought it in and did another 4 coil replacement spark plug change.

Did a ~8k on a cross country road trip. Lower MPG (packed Prius + Roof rack/cold winter temps)
Different accelerating (would not say trouble or "rough riding" necessarily.
Started using fuel injector and noticed an increase again in MPG/better accelerating.
Dropped off my Prius at the dealership to get the transmission fluid changed.
They're telling me my Prius is driving really rough and I need to have the spark plugs and coils replaced. I let them know I just had this done within the past 6 months and for now I will just stick with the Transmission Fluid and wait until I've done some research for the coil packs.

Curious if anyone else has found themselves in a similar issue with the coil packs?

Or and advice on what the issue could be. Not sure if I need to look into the battery eventually?
My battery bars generally are above halfway if not almost always charged.

Not sure if there are other details needed.

Thanks!

 

thanks for the reply. I cant answer about the coil packs unfortunately but will look into it. Thank you for the advice.

Started by cleaning my throttle body; did find oil inside - I reset the battery by taking the negative end off for 15 seconds. Drove around and noticed the hiccup with acceleration near the middle bar was not as noticeable. Will see how it goes over this week and look into working on or bringing it somewhere for the intake manifold this weekend.

Thanks for the tips! I appreciate it.

 

Colder morning, initial startup was knocking and after 10 seconds the check engine light came on.
We cleaned the throttle body again yesterday (after a 600-800 miles drive to MA). Maybe that didn't help?
Turned off the car and took another one to work.

Going to rent a code reader, see what cylinders are misfiring. In the past it has been the same ones (2 coil replacements in 2020 and 2021).
Plan to take off the throttle body and intake manifold and clean that with an overnight soak. Replace the throttle body gasket. And then from there see if I should replace some of the coils.

Any other pointers are appreciated. I only took one year of auto tech in HS and my partner is an old school Volvo Guy, so I'm learning a lot.

 

They did, and let me know it was P0301 and P0302. They talked me into doing all 4 cause they couldn't guarantee just replacing 2. I was too scared/lazy at the time to learn more about the problem myself and I regret it. Definitely low hanging fruit for a fix.

Your other posts I've followed on Head Gaskets and EGR has been really useful and informative. Thank you!

 

Progress Update:

Replaced PCV valve yesterday.
Took car around the block, still louder than what I like, but the check engine light had turned off after resetting the battery. Realized that the battery was not reset after cleaning the throttle body.
Today we tested EGR by unplugging and blocking the pipe with a plastering tool. I am fearing its a head gasket but hoping it is the EGR. We drove around the block and the shaking did not seem as bad as normal but still occurring. In my opinion when initially leaving the drive way and pulling in. Started by cleaned EGR ports in the intake manifold. Took out EGR and cleaned it.

I feel like it was very dirty. We held it up to the sun and could not see through it. After cleaning the difference is really visible.

Tomorrow we will put it back together. I think I still may replace the 2 coils, or switch them around. We'll see. I don't feel comfortable driving it to get the code read, and unfortunately can't find a place to rent a code reader for an hour.
Hopeful that the EGR solves some of the issues... or at least buys me some time.
Either way it's been a fun learning process and makes car issues less daunting. Thanks for all the input.

 

Thank you! New to working on my car/forums and will definitely try to include more information/better pictures and EGR flow numbers.
The only thing I can add is that my car's odometer is at 147,000k.

 

Thank you! I just found one online that I think I will order. It will make it a lot easier than just going off the codes I was told 1 month ago.

 

TLDR: things are better for now-ish thanks for all the advice

Updated Progress:
Put back in the cleaned EGR today. Put everything back except the wiper assembly and drove it around the block. Was rattling and I hated even driving it. Drove to get the codes read, popped up P0102, P0113, P0302, P0403. Was bummed because originally it was just P0302.
Looked up the codes (MAF) and realized that didn't get plugged back in my eagerness to drive it again. Whoopsies. Lesson learned.
Plugged back in the MAF. Took the advice from Mendel and moved my coils around. Reset the battery.
Turned the car on, drove for about 5 miles, no codes came up on the code reader.
The driving was much better. There was an initial rattle for a couple of seconds. My rough spot between 40-50mph and right in the middle of the "power?" bar is where I get the most shakes. I was able to drive normally and there was no longer any rough driving.
I do feel hopeful and encouraged that there wasn't roughness.

I am a bit nervous that a) the codes might not have read because some take a bit of driving to signal a warning and b) the head gasket in the future.

I will note that for whatever reason that possessed me; I used to drive with ECO mode on religiously every single time I drove pretty much. I've seen some posts mentioning ECO mode keeping something cooler being involved head gasket failures. I'm not a car or science person for whatever that anecdote is worth. I do regret always driving in ECO.

Side note: cracked a bolt when putting the intake manifold back together. It is the center screw. I have attached a photo. I'm not sure really what to do, but the bottom half of it is still in there. How to go about getting this out to put another one in? Will it cause a lot of damage driving without one? The other 2 of the 3 on the left and right are fine.

Either way, good learning experience, feel more comfortable figuring out the issues with cars.

 

UPDATE:
Check Engine came on yesterday, Reading P0303.
Excited to see as before I had a P0302 code and moved all my coils one over. Got 1 new coil from the dealership. After replacing P0303 in the Taco Bell parking lot (Live Mas) I drove for 30-40 miles and the check engine light went off. There has been no rough riding in start up or any point in acceleration since the coil swap.

So, I'm glad the EGR/Throttle body has been cleaned and the coil replaced. The other coil packs were not OEM from what I can see and couldn't get the shop on the phone. Perhaps they could go out in the future, but we shall see.

I have a 250 mile drive up to MA this weekend and if there are any issues/codes that come up I will update for others with EGR/Coil issues. Thanks again.

 

sorry for the late response -
We’re about 2 years later, and I haven’t had any issue codes or check engine lights come on since replacing the p303 coil pack.
I have had a cold winter in MA and some cold mornings I worry I have another of the after market ones headed south but will deal with that if the time comes.
Hope youre still cruising with the 200k.