mikespike2

Hello,

I have an 00 Accord 4 cylinder with 105k miles.

When the car sits for >1-2 hours, and is then started, it will often stumble. Not every time, but more than 75%.
I think some call this a hard start? It will stumble with the rpm around ~500-800, and then after maybe 2 seconds jump up to the cold start idle of 1200 rpm and run perfectly.

The only time it sounds rough is for that first 2 seconds after starting. It otherwise runs and drives perfect, and does not ever stall.
Does not appear to correlate to hot or cold weather, but the low here is only 55F right now anyway.

If I turn the engine off and immediately restart, it will never repeat the symptoms.

I just installed a new OEM ignition switch. I initially thought it was fixed, but 3rd start it started repeated the same symptoms.
There are no CEL codes, and I even reset the ECU to let it go through all the readiness flags, and no CEL came up.

I always hear the fuel pump priming. I've even tried priming the fuel pump several times but it doesn't seem to prevent it from happening.
I unplugged the IAC per the service manual, and the engine responded as expected for one that is OK.

I don't want to throw parts at it, and not sure what else to check.
Suggestions? I've read cam position sensor, crank position sensor, and ignitor as possible parts? Fuel pressure reg?

RedTRex

When was last tune up? Try dumping a can of Seafoam in the tank. and last thought right now is leaky fuel injector(s).

mikespike2

Just changed the oil. The timing belt, plugs, and cap/rotor (OEM) were changed in the last 5k miles. Issue didn't seem to correspond with any of them so I don't think it was maintenance related.

How can I check for leaky injectors?

It does seem fuel related, with pressure dropping over time?

RedTRex

Normally only those places that service injectors. If you can figure out how to get a test gauge attached to the fuel rail you can see how long the system hold residual pressure.