Rough idle, hesitating
 

I drove about 80 miles yesterday, no problem. This morning the engine was idling rough when I started the car and hesitating going uphill and at red lights. When I back up it seems like there's a bit of gas smell.

Mechanic says to change the spark plugs. Do you agree? The car has 87,000 miles. The manual says to change the spark plugs at 97,500 miles. This is a 2014 car.

I couldn't get an appointment to change the plugs until next week. Will I be OK until then? I don't want stall out in the puckerbrush.

Actually, changing out the spark plugs could be the cheapest thing you do to help solve your issue.

It may or may not work, but it's a good starting point!

Not sure I would want to continue running the vehicle if you think you will become marooned somewhere.....

A car from 2014 most likely(almost definitely) has individual ignition coils for each spark plug. When 1 goes bad the car misfires and kind of vibrates and shakes. You lose power. The cylinder that isnt getting spark from the bad coil still gets gas and the car runs rich (too much gas) because of the bad coil. You may smell fuel when this happens. If you can access the coils (usually on top of each sparkplug) when the motor is running, unplug a coil 1 at a time. If the motor shakes even worse that coil is good. Plug it back in and go to the next, then the next. If you unplug one and there is no change thats the bad coil. If you havent driven much you probably only need to change the coil. If you have driven more than 5 miles you should change the sparkplug as it has been getting soaked with gas. If you drove a lot of miles change the oil and filter as that gas gets past the piston and into the oil pan. My wifes Toyota took 4 hours to change all 6 coils after 1 went bad. The ones in the back were horrendous to change. My Honda took 20 minutes to change all 6 after 1 went bad.
PS: both my cars have over 150,000 miles before a coil went bad but they can go bad at lower mileage. Amazon is the place to buy the parts to save a lot of money. No need for name brand or the car manufacturers brand as they are all made in China these days! My Honda was 75 dollars for 6 coils on Amazon, 50 dollars for 1 at the auto parts store.
Good Luck !

Car idling rough and hesitating
 

Also have your catalytic converter checked

Forgot to say, dont keep driving it until fixed. The extra gas not getting burned could cost you a 1500 dollar catalytic converter !!!

Thank you for the helpful information. Will it do any damage if I continue driving until next week?

I think I found the answer to my question at https://rustyautos.com/can-i-drive-w...lty-coil-pack/

"It is possible to damage your engine so unless it’s an emergency, I wouldn’t put undue stress on the engine. Running the engine on a cylinder less will mean the car is underpowered and off-balance. Note also that most cars will register a faulty coil and immediately stop gas feed to that cylinder. However, damage may be caused if the fault isn’t registered by the PCM and the dead cylinder continues to receive gas. Your catalytic converter and oxygen sensors may become contaminated by raw gas and need to be replaced. Raw gas will dilute the motor oil too and put major mechanical components at risk. Any misfire should be repaired ASAP."

That sounds pretty serious. I think I should pick up a coil pack in addition to spark plugs and see if I can get an earlier appointment. Thoughts?

I had two brand new non-factory coils go bad within a year of installing a replacement engine in one of my vehicles. Guess what I ended up buying after already buying the new ones?


OP - before spending money, I would check the basics...check that all coils are properly connected and secured and ensure there aren't damaged/frayed wires.

Regarding the odor of raw fuel, I would be checking for a leaking fuel injector seal or you may also be dealing with a sticking injector.

Being that you don't specify the make and model, note that there are auto mfg's with open recalls due to poorly secured fuel system components. A friend of mine had his Hyundai go up in flames 2 miles from taking it to the dealer to have the issue repaired.

I would avoid driving it. I learned the hard (Read: not too bright) way.

I had a 2007 Tahoe with about 100,000 miles on it. A coil went bad although I didn't know at the time what the problem was.

I was in Exeter so I drove it home to Gilford but it was running rough the whole way. I shouldn't have. I bent somethings in the engine and caused more damage. I ended up replacing the engine at a cost of about $7,000.

Next time? I will call a tow truck!

What ever you do, don't park it near your furnace! :D

:laugh::laugh::laugh: I hope he doesn't! Thanks for the morning laugh!

Hey, I'm just trying to keep you guys busy with new questions. Admit it, you think I'm incompetent (no, I cannot change a spark plug***) but you like debating about my calamities.

Apparently coils last about 100,000 miles (no agreement about this online, though). Since the car has 87,000 miles, I thought I should pick up a coil pack ($113) and get that replaced at the same time as the spark plugs. My mechanic points out that the check engine light isn't on and the problem isn't severe yet. He said it only takes a minute to change the coil pack in addition to the spark plugs, but he doesn't recommend changing the coil unless it's failed, so "It's your call."

***In the 1970s I owned a Datsun pickup truck with 65,000 miles. That was old back then! I had to change one or more spark plugs every 1,000 miles or find myself driving on two cylinders! For some reason that was easy to do on that vehicle.

2014 Chevy Sonic

Your mechanic doesn't recommending replacing the coil unless it failed ?????
Thats like saying dont replace that tire until it goes flat !

Get a better mechanic !

Sailaway again, you need to fix your furnace first ;)
Kidding

Is the Engine light on? If it is you need to get the codes read out. Bad coil would usually throw an error code and engine light.

If a cylinder is not firing it can ruin your expensive catalytic converter.

This isn’t the same folks that you had fixing your furnace (excuse me boiler) is it?

Good mechanic should zero right in and not be guessing. That’s why I ALWAYS got to the dealer. They will know the car inside out and sometimes it’s a free recall, like defective head. Save money in the long run. Computer will probably know exactly what’s wrong than trial and error Mike around the corner.

Could be plugs, PCV valve, vacuum leak, bad coil, bad gas, timing chain slipped a tooth, crack in intake manifold, bad injector (if it had them).

Smell of gas is a big hint though and eliminates a bunch.

Is the smell from under the hood or the tail pipe?

I'm not driving the car now. Just staying home shoveling snow. (Don't one of you guys want my Toro PowerClear 721 snowblower?)

CE light is NOT on. My mechanic has been pretty good over the past year that he's been working on my car. He is conservative with my money, which I appreciate. Yes, it could be some of the things you list, but at 87,000 miles it's getting close to needing new plugs and ignition coils, so that's a logical place to start. If that doesn't work, I'll investigate other possible causes. I smell the gas inside the car. I also noticed a drop in gas mileage recently.

Where did the car come from?
 

SailinAway: you said you'd had thisa mechanic for a year? Who worked on it before that? More to the point, did you buy the car new? From a brand dealer or a used car lot or an private sale. Back up question: Is it possible the 87,000 is not accurate? I bought a car new once and there was an accessory: rally dash available from the manufacturer (gauges instead of lights. I bought it and the dealer installed it. Bingo, my 10 month old car had zero miles on it. When it was sold several years later the title said "unknown" for mileage, but I could have just as easily written in 103,000 which was on the odometer.
The good thing is, "Trouble comes in threes." First the roof, then the boiler, now the car. You should be safe for a long time to come.

Good questions, Descant. I bought the car in 2019 from a non-Chevy dealer in southern New Hampshire (it was a trade-in from their customer). It had 68,000 miles; interior and exterior looked close to new, so it appeared well cared for. Before I bought it I had the car thoroughly examined and test driven by Scott Sanborn in Laconia, who I also trust a lot and recommend. He found no real concerns. I also did a really thorough review online of hatchbacks, read the professional reviews. The Chevy Sonic was my 2nd choice after the Kia Soul. It's mechanical reliability was rated close to the Honda Fit, so highly rated in its class. (I know you guys aren't interested in small hatchbacks, but I am.) The Sonic (in my view) is the result of the government telling GM in the 2008 crash, "We will bail you out but you need to make better cars."

So no, I don't think it's possible that the odometer is inaccurate. In the 20,000 miles I've put on it it has needed a new battery and one very small repair. I think the plug and coil wear are reasonably consistent with the mileage.

So problems come in threes? Would that be three per year, three a month, or what?

Might not necessarily be pertinent to your situation but is it a turbo engine?

Also, this mileage thing about coils dying around 100k I'd have to disagree with. My Tundra has 230k, factory coils. My wife's Forester, 128k. In all the vehicles I've owned that were well over 100k, I've replaced a total of 5 coils........4 of them were replaced because, as I mentioned, I bought non factory coils and two died within a year.

Also, in my opinion, your vehicle is new enough that if there were a misfire related to a coil your ECU would almost certainly have seen a constant CEL or perhaps a flashing CEL during the misfires.

Not a turbo engine. I agree about the coils. I've never replaced the coils on any vehicle. My Toyota Corolla went 240,000 miles on the original coils.

There can be a diagnostic scan tool hooked up to the data port to check the ignition coils to see how they're firing. Perhaps the mechanic can do that before replacing the coils. May save you money before replacing parts you don't need to yet. Spark plugs are cheap. Coils can be expensive.

Had a new Chevrolet. About 6 months in had a minor skip in engine. Intermittent.

Come to find out - after extensive examination at a dealership - one of the spark plug coils - was not tightly secured as it should be. No parts replaced. Just put in/snap/connect the one coil. The coil was connected. Just not 100% connected.

Now if there is gasoline smell. That is another story. Have fuel lines checked as well as fuel pump.

And as always. A vehicle of this vintage should have annual oil undercoating to prevent rust.

Problem solved! (I hope)
 

Changing the spark plugs did not solve the problem. Changing the coil pack did. I appreciate the advice here to not drive the car. I only drove it a few miles since I posted 10 days ago. Thanks again to everyone! Much appreciated.