What’s up with rough-running Accord?
My daughter has a 2000 Honda Accord Coupe with a 3-liter V6 engine. Sometimes, after a hot restart, it will run very roughly. In fact, it usually stalls. This happens year-round, though more often in the spring. If she’s able to get the car in-gear and proceed, it’ll generally smooth out and run just fine. But more often, she shuts it off and waits until the engine cools. It will then start and run normally. When this happens, it seems the engine misses on multiple cylinders and there’s lots of unburned gas in the exhaust. I put a cheap scan tool on it, and the device returned the following codes: 300, 301, 302, 303, 304, 305, 306 and 1399. I plugged this info in online and found a plethora of possible causes. Have you seen or heard about this issue? — Kevin Hickman
The diagnostic trouble codes you listed are meant to tell you there are misfire conditions in each of the Accord’s cylinders plus a random misfire situation. A number of things could be happening here. I’ll mention the most likely.
It’s always best to make sure you’re caught up with standard maintenance on such things as the spark plugs and filters or, in the case of aHonda, valve adjustments.
Assuming all that checks out, my next area of concern would be the fuel odor you are noticing. Honda issued a service bulletin just after your car was built, advising that in areas with cool winters, it’s possible to encounter exactly your symptoms during a warm snap.
Because winter fuel is blended with higher volatility to help with cold-engine performance, the fuel can wind up vaporizing too easily when you’ve got suddenly warmer weather and a hot engine. Your symptom is known as a “hot soak” condition, meaning a high under-hood temperature (hot engine, no airflow) is causing problems.
Honda’s recommended fix for Accords like yours is installing a replacement fuel pressure regulator calibrated to higher pressure (resists fuel boiling) and a replacement powertrain control module calibrated for the change.
But before spending about $700 for those parts (at least they’re easy to install), I’d check the car’s residual fuel pressure. If it falls quickly, that’s the problem.
Your next step, if needed, will be to egg on the symptom by idling the fulltemperature engine for five minutes prior to shut-off on a warm day. Wait the typical 10-15 minutes. If the restart symptom appears, quickly shut the engine off, open the hood, and heavily mist the fuel rails and pressure regulator with cool water. These parts are under and between the six curving manifold tubes atop the engine. Try restarting the engine. Itmay still start hard, but we’re looking for an improvement or change from what’s been typical. If a change occurs, the bulletin-recommended repairs are suggested.
If not, other possible causes for hot soak problems include a flaky throttle position sensor or incorrect engine coolant temperature. (Observe for correct throttle position and engine coolant temperature using the cheapo scan tool, comparing the figures to a time when the car’s operating normally). Another possibility is a stuck-open exhaust gas recirculation valve. This can be verified by observing the valve’s lift sensor value when the symptom occurs, which may require a higherend scan tool. If it’s above 1.25 volts, the exhaust gas recirculation valve is stuck open.