Hi everyone,

I'm new to the forum. My 2010 EX-L V6 accord with 44,000 miles stalled and was diagnosed with bad spark plugs. The dealer said this is the known issue with the piston rings. He replaced spark plugs 1-4 and did the PCM update. Many others have had this problem I know. My questions are specific.

1) what does this PCM update actually do? If oil is leaking and causing deposits on the spark plugs how the heck is a computer modification going to fix that?? Is this a band aid or a cure?

2) how can I prevent this from happening again? If I go to the dealership every 10,000 miles and have the spark plugs examined will this allow me to detect the problem prior to the car stalling?

I can handle taking the car into the dealership for preventative maintenance such as more frequent oil changes and spark plug checks. What I can't handle is my wife and baby on the freeway daily and worrying the car will stall in the fast lane. I'm not looking for a band aid. I'm looking for a cure.

 

See this thread:

https://www.hondaaccordforum.com/for...sfiring-57123/

 

Hi,
I greatly appreciated your input and link regarding my 2010 Honda Accord engine misfire due to P0303. As I wrote, the spark plugs were changed and PCM was updated. in your link you stated that most of the time this was sufficient. Do you know specifically what the update was because I'm wondering how they can prevent oil leakage and carbon deposits on the spark plugs with a computer update. Makes me wonder if they are just having cylinder 3 fire less frequently so it goes bad less frequently. Also, is there a way for me to be proactive in the meantime to prevent the stall from happening because it was rather scary for my wife on the freeway? maybe have dealer inspect spark plugs every 10,000 miles?

 

Honda had several service bulletins regarding the 2008-2012 V6 with automatics. The V6 automatics had VCM (Variable Cylinder Management); whereas, manual transmission did not have VCM.

Honda TSB 10-033: One or more spark plugs may be fouled, and the malfunction indicator lamp comes on with at least one of these DTCs: P0300 (random cylinder misfire detected), P0301, P0302, P0303, or P0304 (No. 1 thru No. 4 cylinder misfire detected).

The corrective action was to update the software on the car's computer, and replace any fouled spark plugs.

There was no description of the possible cause or what the software update did as part of this service bulletin.

Honda TSB 11-033: The engine oil level is low on the dipstick, and the malfunction indicator lamp may be on with DTC P3400 and/or P3497 (VPS Stuck Off Bank 1/Bank 2).

The possible cause was the VCM (variable cylinder management) function may repeatedly switch on and off during certain light throttle operation, at cruising speeds, on flat roads. This frequent switching can contribute to increased oil consumption. The updated PCM software improves VCM timing during very light throttle operation which may reduce oil consumption.

DTCs P3400 and P3497 occur when the oil level drops to a point where line pressure can no longer support continued VCM operation.

The corrective action was to update the car's computer software.

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The following is part conjecture based on the two aforementioned service bulletins.

Although, TSB 10-33 didn't specifically state a possible cause for the misfire, and a description of the software update, it is most likely related to the improving the VCM timing. Both TSB 10-033 and 11-033 list the same or later software program ID for the 2010 Accord V6 with automatic. So, getting the latest software update should improve VCM timing during light throttle operation.

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Honda subsequently had a more current service bulletin regarding the warranty extension and part of that information was in the thread link in my previous post.

If it happens again, contact the dealership or American Honda as the warranty extension should probably be applicable. They may end up cleaning the pistons and possibly replacing the piston rings in the affected cylinder(s).

 

To anyone doing research on this. Replace the unprotected ground wire underneath your battery tray, I recommend using some NON OEM 0 gauge wire for like 8$, May need to remove skid plate as it is difficult to approach from the top. Once this unprotected ground is replaced, clear codes, MUST CLEAR CODES IF ECU IS IN LIMP MODE. Problem fixed.