Misfire Diagnosis

[arpypat]

Old filter is filthy, any idea how much an OEM filter costs, or would I be good with like a $10 aftermarket option from an auto parts store?

OEM filter P/N is 17220-5AA-A00. It's about $15-20.

You can find it on amazon with free shipping:

https://www.amazon.com/17220-5AA-A00-Replacement-CA12050-Filters-2016-2018/dp/B07X2HW3XF

Sponsored

 

[kshawn]

Yeah drop in the other filter, exhaust shouldn't matter. They can do a quick injector test and probably want $100, I told them it was free so try your luck. I think @kshawn is onto something.

I followed your build, do you think it was because they were pulled and reinstalled? Why would it be worse at idle, just not atomizing? Did meth play a part? Thanks for your insight brother, good luck.

Either becuase of being reused from a failed engine or a bad/old ethanol batch. My guess is atomization. If I do a few pulls it's alot happier after for a bit as well. But after a day or two of commuting, it will get angrier again.

If I'm stopped at allot of lights, on my way to work i'll sometimes throw a misfire light. Hitting the 500s for K.count.

I've also been advised my now semi closed deck, built engine, will anger the K.count normally anyway. So it could also just be that.

Either way new Injectors are going in before the final dyno tune with Derek. Fingers crossed ill hit the mid 400s for HP! Going to throw some Snoop Dog levels of high boost at her.

 

[Syntek]

https://www.civicx.com/forum/threads/p0301-misfire-on-cylinder-1.14271/

Had same issue, misfire on cold start. They changed out the injectors and the problem went away. I was tuned and warranty was honored.

My guess is also carbon build up in the intake valves that causes misfire on cold start. Common problem on DI only motors.

 

[kshawn]

To the OP I wish you luck! Hopfully it won't take honda to long. I forget if you mentioned tune or not, if so flash back to stock. Drive around some before going in.

 

[bbeem]

Awesome, makes sense. Yeah for sure this OEM motor is open deck if they're going as far as putting coolant channels in the head gasket. I'm surprised how strong this tiny block is though. Good luck!

I don't know about long island, NY but I would never trust a dealer here to do non warranty repair. After they diagnose it (or fail to diagnose it in my case) take it to an actual reputable shop. Unless it's warranted it will probably be 2.5x the price of 2 performance shops in my area for example.

 

[CrisSi]

UPDATE: Ran an injector test on one of those expensive scan tools and apparently all injectors seem to be working fine. After that I ran an A/F test and I got these results

it passes on the cylinder it’s misfiring in. Does anybody have any idea of what could be happening?

 

[PowerPerLiter]

My 18 passed for injectors as well.........it still needed injectors...pulling them confirmed the suspicion but at first the master tech I used to write for was stumped.

At this point the injectors should nearly be considered a maintenance item lmao.

I suspect the reason is because we have the "multi hole" injectors geared for efficiency....I believe this is why the symptoms are the way they are (inconsistent, only coding during certain situations and not audibly misfiring during early stage).....one hole gets clogged and off we go down this road.....

 

[bbeem]

Did you get it sorted out?

 

[CrisSi]

Did you get it sorted out?

unfortunately the dealership (not a Honda dealer) And the third party warranty company associated with the dealer haven’t been too cooperative. I’ve had to hassle them and should be hearing from the warranty company soon.

 

[FC3L15B7]

Hey guys, I just recently purchased a 2018 Civic Si with about 38,000 miles on it back in February and I’m at 44,000 now and I’m having some misfire issues. My car is barely modified unless you’d like to consider a K&N drop in filter and a muffler delete heavy modifications. I only use New York 93 for fuel. I keep getting a misfire in cylinder 3 (P303). You can hear it because My car pops and gurgles while idling but it’s more prominent during a cold start. The car seems to drive fine, I haven’t had any noticeable loss in power or decreased fuel economy. I switched around the placement of the ignition coils and cleared the code but the misfire still persisted in cylinder 3. I checked the plugs and they seemed fine but I still changed them with over priced OEM Honda plugs for safety. I saw live data on a fancy OB2 reader and even after the fresh plugs it still misfired in cylinder 3. The live data showed a misfire count of 15 while idling and about 55 when held at 2000ish rpm. I proceeded to use seafoam fuel injector cleaner but I won’t know the effectiveness of it until my next fill up. The light came back on a few minutes ago and although I didn’t check the codes yet I’m pretty sure it’s gonna be P303 I’m losing hope so I was wondering if anyone on the forum could bestow their knowledge onto me and possibly help me diagnose my problem. Thanks for reading this

Did you check the plug wire for constant spark? The plug wire/insulator could be bad. The spark may be arching instead of firing the plug.

 

[das borgen]

Go to the Honda dealer! Stop dealing with the 3rd party warranty people. Why would you send your car to a non-Honda dealer too?

The warranty on the powertain is 6 years and no mile limit and your car falls squarely under those limits. It was extended a year ago due to the oil dilution problems on the 1.5T

https://www.consumerreports.org/car...a-extends-warranty-on-troubled-turbo-engines/

 

[Gotch]

Injectors are not part of the power train extended warranty. They fall under a 3yr/50k (km) emissions system warranty that is separate. May be different in the USA, ie 30k miles.

 

[Gotch]

Did you check the plug wire for constant spark? The plug wire/insulator could be bad. The spark may be arching instead of firing the plug.

The 1.5L Turbos have coil on plug. The wires going to the coil are low voltage but could still be an issue if damaged.

 

[FC3L15B7]

The 1.5L Turbos have coil on plug. The wires going to the coil are low voltage but could still be an issue if damaged.

Yes, good catch. The wires are still in question though.

 

[das borgen]

Injectors are not part of the power train extended warranty. They fall under a 3yr/50k (km) emissions system warranty that is separate. May be different in the USA, ie 30k miles.

Good point there

https://www.google.com/url?sa=t&sou...FjAAegQIBRAB&usg=AOvVaw08a1dxcEq8eZK0ZXAXQ643

It's still worth a shot. Your car, OP, might still fall under that. The earliest Si were only delivered in July 2017 and yours is under 50k miles.

Either way, take your car to the Honda dealer ASAP

Sponsored