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Discussion Starter #1
i have been battling to fix this misfire and would appreciate any help, tips, thoughts on what could be causing. it started right after my TLS/RL Camshafts install

it usually happens during cold start up

what has been replaced from this List:

Common Problems That Trigger the P0300
Worn out spark plugs, ignition wires, coil(s), distributor cap and rotor (when applicable)
replaced 6x Spark Plugs NGK and 6x Ignition coils (used). do we have a distributor cap?

Incorrect ignition timing
i could not recreate the problem when i took it back to my Camshaft installer so hopefully it isn't this

Vacuum leak(s)
any thoughts from where if any??

Low or weak fuel pressure
any thoughts/suggestions?

Improperly functioning EGR system
swapped for a brand new Genuine Honda EGR for $300.00 - still misfiring

Defective Mass Air Flow Sensor
swapped out today at Acura since i have upgraded 3.7 TB and Manifold from MDX 2010. $50.00 brand new genuine Honda/Acrua part

Defective Crankshaft and/or Camshaft Sensor
i went to a junkyard and found the location of both our Sensors for V6 to be on the left side? if so, its behind the timing belt possibly?


Defective Throttle Position Sensor
i replaced this recently

Mechanical engine problems (i.e.—low compression, leaking head gasket(s), or valve problems
it doesn't feel like any of these. Accord still runs great, just HATE seeing Check Engine Light blinking and/or coming on


Common Misdiagnoses
Fuel Injectors - picked up a used set plus rails but install is pretty extensive and would rather do Transmission Cooler install before this
Oxygen Sensor(s) - i believe there are four, 2 upstream and 2 downstream. one may need replacing due to sitting on my PCD and becoming melted a bit. maybe this is the cause of CEL?
also, i had an Exhaust leak from the Flex Pipe on my Tsudo J Pipe so that Flex Pipe was properly fixed for $200 since welding is beyond me


Powertrain/Drivetrain problems

Thanks for any help, suggestions, advice

at this point, i am at a dead end...
 

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I know nobody uses this forum much anymore, so hopefully you figured it out. I am limited on my knowledge but it seems you threw a lot of money at it, so hopefully it has straightened out.

I can't talk to the new camshafts, but I had an issue with misfire and 02 sensor at the same time. If you have a decent OBDII reader, try to look for pressure in each cylinder and see if one is misfiring. Also, when re-setting your codes, make sure you're only in the Second ignition position and the car is not on, it will click.

I can't imagine I helped, but maybe help think of other ways to tackle.
Thanks
 

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Hey there. I actually just joined this forum, but I’ve had my accord for awhile now.

I recently had the same problem, except it was codes p0300 all the way to p0306. Turned out to be a faulty coil in cyl #3, but took awhile to diagnose, as the coil I replaced it with initially was cracked from napa. Was about ready to check timing when I noticed this. Ended up returning and exchanging it, code has gone away since it was cleared. I also replaced plugs as I have 260 thousand km and haven’t done it in awhile.

My advice would be to let the car idle, and pull off each connection to each of the coils individually. If you remove a connection and there is no change in idle speed, the cylinder is dead (no spark, air, fuel, compression). It is difficult to diagnose with the code reader I find, as one dead cylinder (In my case) causes the engine to change the timing and throw a code on each cylinder. However, you say the car seems to run ok other than the CEL, so this may not be possible.

If you are unable to diagnose the problem to the an individual cylinder/cylinders, I would begin to look into other possible issues such as vacuum leaks/air delivery, corroded/disconnected wiring to sensors, fuel delivery, compression, and timing. Perhaps something was missed after the cam install? Not trying to discredit your installer.

Oh, and try to do it in an order where you don’t have to constantly disconnect/reconnect stuff to check that certain components are functioning as intended. Saves a lot of time. Start with the easiest stuff and try not to get frustrated. Wait till she’s firin’ on all cylinders and then pay it back by layin a beating on er hahaha. The old Italian tune-up😂

Also I edited because I had a thought about the camshafts. Seems weird for this to happen around the same time. I would ensure timing is correct and double check wiring to camshaft sensors and such. Also thinking that the stock j30 ecu may not like the cam upgrade, although I cannot personally comment on this as I only have intake & exhaust mods. As far as I can tell from reading, no ones posted about issues of running upgraded oem acura cams on the stock ecu. Perhaps someone else may be able to speak more about this. I feel like the stock ecu would be able to compensate for the more aggressive profile, as long as the timing and such is set properly. Curious, are you on stock valve springs and such? Anyways, I feel like as long as the necessary steps were taken and everything was reinstalled as was, this shouldn’t be the issue. Seems like weird timing for the issue to occur without somehow being related though.

Best of luck. This is actually my first ever reply, hope it’s at least somewhat useful!
 

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hahaha i had a similar issure and ended up replacing my plugs, coils and throttle position sensor but to no avail.

found out that my CAI located right by my driver side front tires was sucking in some water from the rain due to no underbody panels
 

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Sh!t eh, that’s not good hahaha. Sounds like you got lucky and didn’t take a whole lot in, water can really mess a motor up since it doesn’t compress in the cylinders. I’ve seen people hydrolock their engines from that (albeit, not on these vehicles, on a 4 cylinder with the CAI tucked way down in the fender by the wheel with no plastic liners around, and he drove though a deceptively deep puddle).
I’ve been worried about that as I also rock the no underbody panels and am missing a bit of fender liner. My intake stays pretty high in the bay though so I imagine I’ll be ok.

I’m curious if the OP ever resolved this issue. Just recently had a friend who also had this issue on an 05 V6 AT, and it was just a coil for him as well. One coil, but a code for a misfire in each cyl as well as a random. Crazy how one coil throws the firing on all cylinders outta whack.

I imagine this has probably been resolved now, but misses can be tricky once you’ve ruled out the easier things.
 

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Discussion Starter #6
I know nobody uses this forum much anymore, so hopefully you figured it out. I am limited on my knowledge but it seems you threw a lot of money at it, so hopefully it has straightened out.

I can't imagine I helped, but maybe help think of other ways to tackle.
Thanks
I know! if you read some of the Old threads, this Site was epic. lost of super knowledgeable Members.

i feel like i got in at the tail end of it all


the 7th gen. Accord is now a 17 year old car so most of the guys who had money to buy a 7th gen. brand new in 2003, probably bought something even better
 

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Discussion Starter #7
hahaha i had a similar issure and ended up replacing my plugs, coils and throttle position sensor but to no avail.

found out that my CAI located right by my driver side front tires was sucking in some water from the rain due to no underbody panels
dude get those underpanels! i've replaced mine a couple times because i got 18s...they can be had for super cheap at any junk yard
 

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Discussion Starter #8
I’m curious if the OP ever resolved this issue. Just recently had a friend who also had this issue on an 05 V6 AT, and it was just a coil for him as well. One coil, but a code for a misfire in each cyl as well as a random. Crazy how one coil throws the firing on all cylinders outta whack.

I imagine this has probably been resolved now, but misses can be tricky once you’ve ruled out the easier things.
my installer was leaning towards thinking it needed a tune. i was thinking it might have been the Valve adjustment specs?

the only tuning option for Automatic is Boomslang (which was $75 bucks back in the day, is like $300+ new now) and a Apexi Neo (another $200)

what sucks is even if i got these 2 parts to tune it, from what i read, the ECU will eventually DETUNE and i would have to go in constantly for another Tune


at this point, i've had my fun with it and glad it got to 300,000 with minimal problems other than of course, the Very weak Automatic transmission
 

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Valve specs could be it, a tune possibly. I’ve heard of people getting misfires due to slightly bent valves as well from overrevs and such, however this seems like a fairly fresh build. You could always make sure the tolerances are within spec, it wouldn’t hurt. It’s hard to diagnose a misfire, especially without ever seeing the car lol
 

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I was having the same issue. I replaced spark plugs and they weren’t the issue. So I order all 6 ignition coils and installed them. It fixed my problem. No flashing engine light. No solid engine light. Here is a link to a YouTube video where you can test your ignition coils to see if they are the issue... https://youtu.be/9GkBefhVtJU
 
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