Intermittent engine vibration on cold start, E36 M3
I have a E36 M3 with 83k miles on it down here in California. I notice that during a cold start (first start of the day), the engine vibrates the car intermittently. Not a high frequency vibration (ie low idle), but the car sorta feels like it's lightly twitching every few seconds for the first 20 seconds it starts. After that, engine is smooth. Haven't heard any knocking.
Any ideas on what's happening? Is a piston seal rubbing? Is a rod bent? I've no idea. The car makes good power, doesn't burn oil and doesn't make weird noises - but the shakes are certainly piquing my curiosity.