Slight shaking upon startup

96 Hyundai Accent again. About 128k miles on it. Today I noticed that upon start up there is a bit of a shaking to the car. It sounds like something under the hood is shaking immediately after I turn the ignition. It drives okay, although there is still some shaking at high speeds (see my previous thread). It didn’t do it on my first start up this afternoon, though, only when the engine/car was warm.

Any ideas?

There is not much information here, but I suspect a routine spark plug change might be in order. If you have not had fresh spark plugs in a while, replace them now. Let us know if this solves your problem.

Also, look for cracked motor mounts. This is about the age for the rubber in the motor mounts to fail, and break.

I just had the plugs changed in September, I believe it was, and had the wires changed in November. Just out of curiosity, I let it sit for about 90 minutes, started it (sounded/felt normal, no shaking), drove it around the parking lot a few times to warm it up (temp gauge in normal range, but not as hot as it was when I heard/felt shaking earlier) turned it off and turned it back on again. No shaking on the second start up either. The battery is almost three years old. Could it be an old battery or just a temp issue?

Motor mounts were suggested in my previous thread and by the tire shop. This sounds like a dumb question, but I’ll ask it anyway: would the motor mounts only shake when the car/engine is hot, due to the fact that metal expands?

I’m being kept awake by loud neighbors, so I might as well post this additional thought/question: Could this hot starting noise have anything to do with the fact that my a/c was diagnosed last fall as being on the fritz? My coworker’s mechanic husband listened and told me that the compressor switch was the specific problem,