I have a 92 Accord 4cyl that starts right up every time and runs smooth and fine, except right when it starts. Usually for 1-2 seconds it is really rough, then fine. It is more noticeable on cold starts. I just replaced the spark plugs thinking that may help. It did need the new ones but it didn’t fix the problem. Any thoughts? Thanks.
The spark plug wires should be of recent vintage. Replace the distributor cap and rotor. These parts which conduct the spark DO deteriorate. Several tens of thousands of volts pass through these parts each time a spark occurs. Disconnect and clean, or replace, the battery cables. Lessened amperage to the starter, and spark producers, could slow the start.
My guess is that you’re losing your residual fuel pressure when the engine is not running.
The fuel pump has a check valve that maintains this pressure.
The rough running is caused by the brief spell when the air is being bled out of the system.
You can try cycling the pump on and off a umber of times before starting it and see what happens.
Turn the key to ON for a few seconds, off, back ON, etc. about 7 or 8 times.
Then hit the START position. If it runs fine you know the check valve is the problem more than likely. This means a new pump also.
There are other things it could be (leaking injector, fuel pressure regulator, etc.) but the pump check valve would be the 1st thing on my list.
Hope that helps.