"Jez" <jeremy@ainsworth.me.uk> wrote in message news:lNKdnasqBPPii9DenZ2dnUVZ8qOdnZ2d@pipex.net...

> >>I posted about this a few weeks ago. The RPM on my civic is
> >>hunting/oscillating by +-200 when driving at roughly 35mph up a light
> >>hill with the correct throttle position to maintain that speed. It's
> >>indicated on the gauge, by changing engine sound, and by very gentle
> >>thrusting forward whenever the RPM increases. Imagine the RPM needle
> >>going up and down about once or twice per second.
> I should also mention that I don't recall this problem occuring before I
> did an Oil/Oil filter and air filter change last month. Is there any way
> that this might have caused it? I did everything carefully and by the
> book. It's only a thought, the problem could have been there before and
> not noticed it.

At this point it sounds like a lean misfire under load. As you
depress on the gas you are creating a lean mixture. The O2 sensor
should pick this up and compensate quickly. The fastest and
easiest way to troubleshoot this is to disconnect the O2 sensor
connector that goes to the computer. Start the engine and go up
that hill.

Note that you should not drive with the O2 disconnected for a
prolonged time. A good ignition coil should be able to compensate
for the lean mixture unless it's too lean.