Misfire, hesitation, lurching, something? Please help.

[KFactor]

What Hondata system: FlashPro
What vehicle: 2019 Accord Sport 2.0T 10AT
Hondata system serial number: FP-ACRD-US-170604
ECU part number: I have no idea
Calibration: Accord-Turbo-2.0-AT-2018-Flex

Accord 20241015.fpcal

(only one change from base: second 02 sensor disabled because of exhaust)
Datalog(s):

datalog0003excerpt.fpdl

datalog0002excerpt.fpdl

Issue:
***I'm getting a fairly unsettling hesitation or maybe misfire, to be honest I can't figure it out. It happens when the car is still warming up. It sounds like it cuts out the ignition or the throttle plate or the timing is maybe jumping around. In the car it feels like the car is lurching and sounds like a misfire. I thought maybe it was the plugs, so I replaced all of them last week and uploaded a new calibration with all the same settings but it's still doing it. Odd part is that once the vehicle warms up, it doesn't do it but also it feels like the power is reduced. I've stared at these graphs for hours now but my lack of knowledge about tuning has me stumped. My calibration and two datalogs are attached.

I've been running the same calibration for a long time now. I've uploaded the calibration a few times since the beginning of the year, but only after you push out an update. The first time it did this was probably back in April/May of this year after an update you published. I've thought about having a tuner build a calibration for me as the base calibration does weird things from time to time.

My thoughts on Hondata and it's work with the Accord (slight rant):

I'm trying to have faith that you'll give the accords some attention one of these days, but it seems you've been focused on other things. I've been asked several times by other Accord owners why I don't use k-tuner because [they say] it's better for Accords than Hondata but I'm trying to have faith because I like the company and I like how you do things but not so much during the past year because no real improvements have been made. I spent the same amount of money that a Type-R owner did but the level of attention to my platform you've given is not comparable.

[KFactor]

Also, something I noticed is the throttle plate is very erratic sometimes. Not sure if this has anything to do with my problem.

[Hondata]

Is your ethanol content of 32% accurate based on what you have put in the vehicle?

You're running large negative fuel trims - up to -25%.

Go back to E10. Disable ethanol. Check fuel trims and if necessary adjust the AFM to get them correct.

Then enable ethanol.

[KFactor]

Yes, 32% is about right.

Those fuel trims are what is in the base "flex" calibration.

[KFactor]

Is your ethanol content of 32% accurate based on what you have put in the vehicle?

You're running large negative fuel trims - up to -25%.

Go back to E10. Disable ethanol. Check fuel trims and if necessary adjust the AFM to get them correct.

Then enable ethanol.

Forgive me but I have no idea what I'm doing. Trying to learn though.

Go back to E-10, that's easy enough. I'll dilute the remaining 5 gallons with ethanol-free premium and calculate to achieve less than or equal to 10%

Disable ethanol, easy - uncheck box

Fuel Trims:

Fuel Trim.png

You said to check this, not sure what I'm checking.

Adjust the AFM: I made the graph display but I don't understand what I'm doing. This is the full datalog I pulled the datalog0003excerpt from:

datalog0003.fpdl

With this datalog open, this is the graph I see:

Tuning AFM Flow.png

Also, I have a feeling my aftermarket parts have something to do with this, especially the intake from what I've read.

There aren't any modification options for Accord, so I haven't been able to do anything about it as the closest tuner is 3 hours away.

Here are the modifications I've made:
PRL High Volume Intake System
PRL - Race exhaust & Front Pipe Combo Upgrade
NGK Laser Iridium Spark Plug ILZKAR8J8SY Heat Range 8
PRL Intercooler Upgrade
Deleted Intercooler Resonator
DC Sports Exhaust System (3")
SiriMoto FlexFuel Kit

All that said, I'd appreciate any help I can get before I break something. Thank you

[KFactor]

Car still hasn't blown up, but still having the same problems. Can someone please take a stab at recommending something other than what Hondata told me because their advice was absolutely no help.

[Speedbust_r]

Hi,

In your datalog0003excerpt, in "Closed Loop" view, we can observe at 4.3sec, 9.5sec, 10,1 sec and 24.9sec that AF ratios are 17:1 and 18:1.

I've had the same symptoms: it was a faulty ignition coil. So power was cutting and I was hearing post combustion through the exhaust, no misfire or knock count at that time. It went clear to me when the coil failed completly: then it called misfires.

I changed the 4 coils, spark plugs and the O2 sensor: it got damaged by the unburnt fuel or should I say by the post combustion?
I also used Rislone CAT COMPLETE, AF ratios became more accurate.

It's been about 6 months for me, at 180 000KM the car still has its original full power.

As for the ethanol, it destroyed my OEM low pressure fuel pump. It doesn't seem to be your case since fuel pressure is OK in your datalog.

Alex

[KFactor]

Thank you! Alright, I just ordered a full set of ignition coils (Hitachi). Should be here in a day or two. I can tell you that it was 100% NOT my fuel injectors as recommended by my local Honda dealership... Just shelled out $1,500 for that today and it literally changed nothing so now I have a spare set of fuel injectors I suppose. They look fine too. The mechanic tried to tell me I needed to get aftermarket fuel injectors because the OEM injectors weren't capable of supplying enough fuel with my tune which is obviously BS because I ran them with this same tune for four years and didn't have any problems. I also just ordered a Hondata low-pressure fuel pump as I have a suspicion mine is beginning to go as now I'm having starting issues. Your mention of the ethanol destroying yours leads me to believe I'm in the same boat. At the very least, I won't have to worry about my pump being eaten by ethanol. I just replaced my plugs and O2 sensor, so should be ok for those. Dealer wants me to come back in a few days so they can troubleshoot, I'm hoping I can just fix it before then so they don't empty my wallet. Honestly, If I would have seen this message I wouldn't have taken it to them likely would've saved a bunch of money. Hindsight, 20/20, etc. If there's anything else I should think about, I'd really appreciate the help.

[KFactor]

Ok so I've replaced several parts, but I'm still getting what I'm calling a misfire, though it may have a more appropriate name. This is the same issue that my original, and all subsequent posts are about.

I've replaced:
Low pressure fuel pump (w/ Hondata pump)
Fuel Injectors (OEM - Honda Dealership replaced)
Ignition coils (OEM)
Spark Plugs (OEM purchased from Honda)

At this point I'm over $2,000 into diagnosis by part replacement...

Will someone PLEASE take a look at this datalog I just took?

datalog_20251207.fpdl

[KFactor]

I forgot to add to the last post that I'm also having a hard time starting the engine now. It really struggles and seems to only fire on a couple of cylinders for a few seconds then the others start to fire with all four eventually working.

[Spunkster]

Where in the datalog are you seeing the issue?

[Speedbust_r]

While investigating the datalog, It looks like the Injector Phase Table uses ECT2, so it is always pointing 0C or 32F when vehicle is equiped with flexfuel.

Question for Hondata:

What is the proper way to report this potential software bug?

Thank you in advance,

Alex

[Spunkster]

Post calibration with datalogs showing what you are describing.

[Hondata]

That table uses ECT as far as I can tell. It is unusual to use ECT2 for anything other than the routine to check thermostat and operate radiator fans.

[KFactor]

Update:
Car would NOT start a couple of days ago. Replaced the spark plugs (again) and it fired right up. However, it still has the "misfire." Plugs I removed were OEM purchased from Honda (NGK 92411 DILKAR8P8SY). The plugs were only two months old, and based on the heavy deposits, it looks like they're not getting hot enough. That being said, I had a set of old plugs on hand (NGK 95660 ILZKAR8J8SY) that were in better shape, so I put them in just to get the car moving.

I plan to order two new sets of plugs, with the first being a hotter version of the one I just installed, and the second is one I've run before:
1. NGK 95112 ILZKAR8H8S - Gap: .031" (0.8mm) *trying these*
2. NGK 95660 ILZKAR8J8SY - Gap: .030" (0.75mm) *ran these for 3 years without any issues, but was at a high altitude (6,000 ft)*

Both of these have the standard ground instead of fine wire as found on the OEM plug, and also they have an extended projection center electrode. All other specs are the same other than the gap as identified above.

Are there any other plugs I should consider?