When I start the engine cold in my '93 Honda Accord, it will rev up to 2000rpm and slowly go down to 800 rpm as the engine warms up (normal behavior), unless I do one of the following during this process:
- Touch my gas pedal
- Move my steering wheel (power steering)
- Sometimes without a stimulus
- When jumping a friend's car, as he connected the jumper cables to his car, my engine immediately starting doing this:
The revs will go up to 2000rpm then drop down to 1000rpm and cycle every second! My engine will still warm up and the revs will drop as normal, but they will still cycle to 1000rpm (up and down, up and down...) until the engine is warm (idles at 800rpm). I often get weird looks from people as I'm driving around, since it must sound like I'm the one reving my engine.
I took the car to a mechanic but they said it could be anything going wrong, since the computer is not throwing an error. I'm not sure if this is related, but in the dead of winter when it's <10 F, my temperature gauge will barely go over the cold mark, even after hours on the highway (my interior blowers will pump out some heat). This behavior lessens as the ambient temperature goes above 40 F or so.