I've been having an issue with my 2000 Honda Accord 3.0 liter V6 VTEC for over a month now. After the car warms up, then is shut off and sits for 15-20 mins, the car would run extremely rough and die. It doesn't do this when it's cold, or if you let it get warm then kill it, immediately cranking it after shutting it down... it'll fire right back up. Only occurs when it's been warmed up, then sits for a good 15-20 mins before restarting. Initially it showed a misfire on cylinder 1. I replaced the coil pack, and the issue repeated that same day, only then showing misfires on all cylinders. I replaced all coil packs and changed the plugs. The plugs were clean, but I replaced them anyway. The car ran with no issues for a month, then the exact same issue repeated. Same error codes. Normally I would've taken the car to my mechanic, as I am no means all that knowledgeable, but I recently relocated and didn't have anyone to go to that is reliable/trustworthy. Replacing the packs and plugs was a simple enough job, so I did it myself. Obviously that wasn't the issue. I was forced to find someone local, being that this is now outside my scope of knowledge, and it's been a nightmare. The first guy I went to straight up told me he had no clue what it might be, so I found another mechanic. So far mechanic #2 has replaced the fuel pressure regulator, air charge temperature control, idle control valve, gaskets and done a valve adjustment. Got the car back today, after being in the shop since Monday, and it ran for a few hours before the same issue popped back up. I'm seriously about to lose my mind over this. The two mechanics I've used so far have stellar Yelp reviews... that's all I had to go on, I know no one in this area... but have proven to be highly incompetent. At this point I'm not sure there's a decent mechanic in my area at all, and it's making me realize how invaluable my guy back home was. *sigh*. I have no idea what to do now, and any help would be appreciated.

 

Sounds like you are having the "heat soak" issue. Many of the early 6th gen v6's have/had this issue. Seems to show up more in the cold when the winter blend gas is being sold.

There is a tsb where they say to update/replace the FPR and the PCM.

Now, what to do? Well that depends on how far you want to go.

Some have reported that replacing the t-stat with a new one from the dealer has helped.

Some have gone as far as replacing the fuel rails from a newer Accord or from an Odyssey. There is a thread on here where there is some information about this.

 

Thanks for the info, much appreciated! I'm going to weigh my options and decide what to do next... Depends on how much the repairs are going to cost, I suppose.

 

I have a similar problem with my Honda Accord 2000 6 cyl. I have an awesome mechanic, but he is stumped. He has put in many hours on my car, and has charged me very little. He replaced the fuel injector, the coils with used coils, spark plugs and boots, etc. Has only charged me a little over $200. From the receipts from the prior owner, it seems she was having the same problem. This problem dates back to September of 2013.

 

In addition to Poormams post above sometimes the MAP sensor can be the culprit and won't throw a code. If your mechanic has a good used sensor it may be worth trying. Also if your mechanic has a high end computer scanner, ask if they have check the ETC with engine cold, the reading on the computer should be similar to the ambient air temp. Then do the same procedure after running the car.

Additionally the fact that it starter with cylinder 1 miss fire I am wondering if the EGR service bulletin has been completed for the car. That includes honing the primary port on the bottom of the intake manifold and installing a stainless insert. Just some ideas...

 

I had similar symtoms on 94 Vtec 4-cylinder. It was due to coolant leaking into cylinders during hot soak. Upon restart, engine would run rough briefly and clear.

Steady loss of coolant is an indicator this may be the source of your problem. I eventually removed plugs on warm engine and turned engine over to see water spray from the spark plug holes. New head gasket fixed problem.

good luck