07′ Honda Accord Hybrid V6 – Random Misfire Issue

Greetings Car Enthusiasts and Professionals,

I currently own a Honda Accord Hybrid 2007 V6 (J Series), and would like to have your insight in addressing a random misfire code P0300 through P0306 which happens intermittently during idle after turning on the ignition either after the 2nd or 3rd time when I drive during the day. The CEL doesn’t trigger during a cold start but with a warm start, this happens when I crank on the ignition a 2nd time (if I were to make a round trip).

The CEL goes away after a few days or so after a few ignition crank cycles, but would trigger again ever so intermittently. I typically drive most on the weekends.

I’m not a very mechanically adept person, but am an avid enthusiast in learning parts and functions to a vehicle.

I currently have about 106k miles and here is a history of the major work that was performed on my vehicle:

Mileage 104,410 – Performed by the dealer on Nov 2016
– Mentioned to Honda Service that I had oil leak on spark plug coil on Cyl. #6 after doing a DIY examination
– Dealer recommended a valve adjustment, and valve cover and head cover gaskets to be replaced. Spark plug seals were replaced
– All 6 Spark plugs were replaced, and replaced one spark plug coil pack

Mileage 104,841 – Misfire codes triggered once again, and reached out to the dealership service adviser of random misfire P0300-306

– Close to New Year’s Eve 2016, I left my car at dealership service for a week and was kept in the loop by the service adviser of what diagnoses were being done. Was told that spark plugs were fine, compression test ran normal, no issue with fuel injectors and no issues with lean fuel mixture. I asked if there was a possible vacuum leak but I was told that wasn’t an issue, but in the back of my head, I don’t know if they went through each diagnostic step to eliminate anything that was out of the ordinary. I didn’t get any codes of a MAF or O2 sensor when I plugged my OBD tool.
– According to invoice, “Valves were adjusted to max loose side and retested for misfire, did not have as many misfires at this time, cleared all codes, and reset crank pattern learn. Further concern, may need internal engine work”
– A few days after I picked up my vehicle, I cranked the ignition on a cold start and checked my OBD2 and noticed that there were “Pending” misfire codes but the CEL did not come on. After a 2nd crank during the day, ran the OBD2 scan and there were no codes. See below screenshots taken from OBD2.

Mileage 102,185 – Performed by the dealer on Aug 2016
– Timing Belt & Water Pump Service

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Random P0300-P0306 Misfire incidents also dated back in 2012:
Mileage 77,742 Jan. 2012 Invoice
– Dealership service performed PCM Update
– “Confirmed CEL P0300-P0306. Updated PCM with two updates. Ref TSB #10-007. MAP Voltage at 0.99V. Should be at 0.90V. If light (CEL) comes back on, recommend valve adjustment”

Random P0300-P0306 Misfire incidents also dated back in 2013:
Mileage 86,348 Sept. 2013 Invoice
– “Tune up 6 Cyl: Removal/Replacement of Spark Plugs, PCV Valve, Fuel Filter, & Air Filter if needed. Adjusted ignition timing & fuel system”
– Reflash Computer to latest software’
Note: Did not get a CEL for about 7 months after this work, and had a CEL trigger for random misfire codes in Fall 2014.

Nov 2014 – Hybrid IMA battery failed and replaced under warranty at Mileage 94k.

This car has been through a lot, and I’m not quite ready to give up on this vehicle as long as my budget allows. As any car owner can relate, I don’t want to throw away money at a part towards a problem as a simple bandaid to a symptom that has been an ongoing issue. I always have done routine maintenance on my vehicle with oil changes and such. I would love to have every single diagnostic performed to a T before being advised in what to spend on.

Any insight and information will be helpful! Drive safe and have fun!

Cheers,
Chris