I own a 2017 Civic Ex-T Coupe with the turbo 1.5L with a CVT. Beginning in March 2022, i started experiencing some misfire issues whenever the car would exceed 2200 rpm, but not throw an engine light. The misfire would continue when driving the car unless I drove it for more than 45 minutes at a time, then it disappears. I had taken it to a local honda shop and they replaced all spark plugs, filters, and cleaned out the whole fuel system. The misfires disappeared for about a month but then came back end of April. I still had no engine light pop up with normal driving so I just let it be until the second week of May, when I got frustrated one day and floored it when it was misfiring. The car immediately went into limp mode and finally threw a code which was P003 (cylinder 3 misfire). I then brought it back to the local honda shop and they were unable to come to a conclusion why it was misfiring. However, while they had the car, they let the car idle for 1.5 hours then drove it and beat on it, and they didn’t experience any misfire whatsoever. Since we were at a dead end, we brought it to the Honda Dealership where they promptly told me I had a blown head gasket causing me to leak coolant and it was going to be $3.5K. We declined the service and brought it back over to our local shop where he tested to see if it was true and he was able to determine that my oil, cylinders, and engine bay did not have coolant where it shouldn’t be. By now, it was early June and for work, I drove 100 miles each day through downtown Atlanta. Even with putting almost 3,000 miles on the car each month and driving it semi hard, I have had minimal issues. Every couple weeks, it’ll give me a few days of small misfiring, but then clears itself back up. I really don’t know what else it could be but I feel like if it was the head gasket, then my car wouldn’t be running as good as it is at this point since it started over 15k miles ago. Me and my mechanic are stuck where to go, so if anyone has any suggestion or possible insight on what it could be it’d be appreciated it !

 

Hello,

Is the car overheating? Have you (or the other shop) performed a block test?

 

Probably fuel injectors. This is a direct injection engine and Honda is known to have issues with the injectors. 2017 is pretty early in Honda DI tech.

 

I haven’t had any overheating issues (no temp warnings on ecu either), i’ve made sure to check each time I drive, but my mechanic said that I did have a higher than normal cooling system pressure. If i’m not mistaken, my mechanic did a block test, which they referred to as a “carbon dioxide test”, and they told me the test fluid didn’t indicate of any carbon dioxide.

 

I’ve had them cleaned out twice in the past year but haven’t replaced them yet. Do you know if it’s smart to change just all of them? Or just change the #3 one since that’s been the problem cylinder?

 

I have 2019 Civic Hatch LX 1.5 Turbo. I had a misfire on one cylinder. Honda Dealer replaced all four fuel injectors under warranty haven't had any issues since.

 

Dealership replaces them all. It is a fair amount of labor to get to them.

 

Having them cleaned by some shop with some chemicals isn’t gonna work. They are just taking people’s money. They need to be physically removed to be cleaned properly. However at that point, just replace the injector or all injectors. If one is bad, chances are the others aren’t far off.

Ive dealt with this same issue for years on VW tsi engines (CCs mostly) and those injectors are absolutely destroyed and clogged up so bad. DI injector technology is dumb, port injection works just fine. Not sure why the need for these manufacturers to switch to them.


end rant….

 

Turbos and high compression work really well with DI. No chance of pre-ignition. Diesels have been DI for nearly ever and they mostly work great.

It all goes wrong when emissions control stuff gets added into to mix. Probably not a fault of the emissions control but a fault of doing the emissions control for as cheaply as possible.

 

If pre ignition is a problem, tuners need to stop leaning on motors so hard. Clogged fuel injectors are the main problem with DI systems. It’s happening more often than not on gasoline engines. High mileage or not. Carbon build up happens no matter what and it’s often much more labor intensive to get to DI injectors than port injectors.


And when they clog up, you gotta get them out and clean or replace (~$300-400 each) for this motor.
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