Need help troubleshooting intermittent misfire

FK2 Civic Type R 2015-2017, FK8 Civic Type R 2017-2021, FL5 Civic Type R 2023+ and Integra Type S 2024+
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sloth4urluv
Posts: 60
Joined: Tue Jan 26, 2010 7:09 pm

Need help troubleshooting intermittent misfire

Post by sloth4urluv »

Mods are the following:
Hondata - Flashpro
PRL - FMIC
PRL - HVI
RV6 - HFC DP
RV6 - FP

Tune is essentially a base map with some custom torque tables (Comfort=Stock, Sport=50%Blend, +R=Hondata)


The issue that I am having is intermittent but seems to be most reproducible during mid RPM part throttle.
Threw a code once for misfire on cylinder 2 (P0302) and I took it to the dealership but they were not able to reproduce it.
I did have them run a compression test while it was there and all the cylinders seemed to be around 130 psi (seems low but I assume the dealership would have said something if it was far off).

The datalog I got this morning seems to be the most helpful for troubleshooting.
At around 13:56.4 the AF spikes to 15.45:1.
The AFM stays constant, the BP stay constant, the DIFP stays constant, and the injector DUTY stays pretty constant.
04-25-2022_RV6_To_Work1(M).png
04-25-2022_RV6_To_Work1(M).png (77.96 KiB) Viewed 1586 times
This leads me to believe that the issue is likely not a leak on the intake side.
Also if I was having spark issues I would assume that the AF would spike rich instead of lean.
I'm also assuming that the low pressure and high pressure fuel pumps are fine since the DIFP is staying constant (Unless the event happens too quickly to log).

My best guess is an issue with the fuel injectors. (Cylinder 2 would be the most likely candidate)
If anyone else has any suggestions of what else to look for I would appreciate it.
Attachments
Sloth4urluv-Calibration(04-25-2022)(RV6).fpcal
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04-25-2022_RV6_To_Work1(M).fpdl
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Hondata
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Re: Need help troubleshooting intermittent misfire

Post by Hondata »

Also if I was having spark issues I would assume that the AF would spike rich instead of lean.
Nope, a misfire shows as lean because a cylinder worth of air passes into the exhaust.
Hondata
sloth4urluv
Posts: 60
Joined: Tue Jan 26, 2010 7:09 pm

Re: Need help troubleshooting intermittent misfire

Post by sloth4urluv »

Thanks for the clarification.
I guess that would bring plugs and coilpacks into question as well.
I would like to assume that they at least inspected the plugs when I had them compression test the engine but who knows...

I have new plugs on the way anyways, I should probably order a coil as well for troubleshooting/spare.

Thanks again for the help.
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Hondata
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Re: Need help troubleshooting intermittent misfire

Post by Hondata »

#1 thing to check is if a plug is cracked.
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sloth4urluv
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Joined: Tue Jan 26, 2010 7:09 pm

Re: Need help troubleshooting intermittent misfire

Post by sloth4urluv »

Replaced the plugs last night and got some pictures with my bore scope.
I assume cylinder 1 is on the passenger side of the car.
(Although that seems backwards to the compression test results)
Cylinder 2 looks a little dirty. I’m not sure if that is a result of poor combustion or something else. Any feedback on that would be appreciated. I didn’t see any obvious signs of cylinder wall damage.
Cylinder-1.jpeg
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Cylinder-2.jpeg
Cylinder-2.jpeg (175.38 KiB) Viewed 1567 times
Cylinder-3.jpeg
Cylinder-3.jpeg (120.49 KiB) Viewed 1567 times
Cylinder-4.jpeg
Cylinder-4.jpeg (116.84 KiB) Viewed 1567 times
Plugs-1.jpeg
Plugs-1.jpeg (623.58 KiB) Viewed 1567 times
(Plugs are labeled as they were removed from the car. As part of the dealership’s troubleshooting they moved Spark Plug 2->3, and Coil2->4)
I don’t see any obvious cracking or carbon tracks on the plugs.

Car seems to be running fine but the problem has been intermittent, I will keep an eye on it and post updates.
Replacement coil packs and injectors are on order.

At this point I'm convinced that it is a fuel injector.
As I said in the post they swapped plugs 2&3 and looking at the pictures of the plugs #2 look white (lean), and plug #3 which used to be in cylinder 2 is fairly white but looks like it browned a little bit since it has been in cylinder 3 for a few weeks.

Also looking back at the report the dealership did the compression test resulted in 167, 164, 159, 165.
Either I have cylinder #1 wrong or the report looks backwards.

Any suggestions on what my next steps should be?
At this point even if I get the cause of the problem resolved I am concerned about the long term health of the engine due to this.
I would like to get evidence that the cause of the issue is due to a faulty injector and get the repairs covered under warranty as the car is only around 35K miles.
sloth4urluv
Posts: 60
Joined: Tue Jan 26, 2010 7:09 pm

Re: Need help troubleshooting intermittent misfire

Post by sloth4urluv »

So I took the car to the dealership again yesterday and since they didn’t have the tools to test the fuel injectors they were not able to find anything.

Since I replaced the plugs the car seems to be running fine but it is only likely a matter of time before it starts acting up again.
I still suspect that it is a due to a fuel injector issue.
I had a replacement set on order but it was canceled due to a nation wide back order.
Is the Hondata fuel system still in stock?

Additionally I had a thought on how I could possibly test for a partially clogged injector in the car and would like some advice from you guys.
My thought is that if I adjust the individual fuel trim for each injector one at a time to add more fuel and wait for the ECU to stabilize the trims at idle I can compare the total trim I should be able to see if one injector is flowing less than the others.

I have the following questions that I am hoping you can answer.

I’m assuming that that the ECU trims all of the injectors together to reach the desired AFR and doesn’t have enough information to trim individual cylinders correct?

There is currently not a way to live tune the individual fuel trims is there?

What would be a good trim amount to test?
+8%? (Needs to be high enough so that a clear difference can be noticed but not too high that the engine won’t be able to idle properly)

The Hondata dash app reports trim values as floating point, and they show up as integers in the log. Is the dash app doing averaging or is this a limitation of how the logs are being stored?
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Spunkster
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Re: Need help troubleshooting intermittent misfire

Post by Spunkster »

You should pull the plugs and check them after a week of driving and see how they look and see if one has unusual wear.
sloth4urluv
Posts: 60
Joined: Tue Jan 26, 2010 7:09 pm

Re: Need help troubleshooting intermittent misfire

Post by sloth4urluv »

Spunkster wrote: Mon May 02, 2022 9:41 am You should pull the plugs and check them after a week of driving and see how they look and see if one has unusual wear.
Thanks for the advice, will do.
Any info on the floating point vs integer representation of the trims?
Also, a bit off topic but as a feature request could you guys add the ability to add more than 4 graph windows to the Flashpro application (or open more than one graph window so I can look at more than one template at a time)
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