Engine Performance problem
1996 Honda Accord 4 cyl Front Wheel Drive Automatic 195000 miles
When it is raining the car loses power on acceleration and emits white smoke that appears to be unburned fuel. No head gasket problems or loss of coolant or oil. Compression test is good. New igniter, distributor unit, wires, cap rotor, plugs. The cat is not plugged. Fuel is good. It runs great on a dry day. Have sprayed engine and fuel tank area but can't replicate the problem. On a wet day, real slow acceleration seems to work better. It seems like the computer is cutting off the fuel flow. Could the mass air flow be reacting to higher humidity an denser air?
If you mean black smoke, yes you 're using lot of fuel.
A leaky fuel injector, too much fuel pressure, or clogged air filter
white smoke means coolant or transmission.
If the white smoke is sweet, it is coolant issue, if the white smoke is a burn smell, it is the transmission fluid.
If you have unburn fuel, water is acting as a conductor and shorting something out in the ignition system or sensor connection to the computer.
When humidity is high, moisture can condense out of the air and form droplets of liquid on any cold surface. If the surface happens to be a, ignition coil, the ignition voltage may find a shortcut to ground instead of following it's normal path to the spark plugs.
Moisture is especially damaging to PCMs and electronic circuit boards. Moisture can cause corrosion that shorts out circuits and causes all kinds of weird electronic problems. That's why flood-damaged vehicles are so unreliable. Sooner or later, they usually need to have the PCM and/or other electronic modules replaced. Your ECM is either located under the carpeting of the passenger's side floor pan, on earlier models or closer to the front console if you have later model.