94 Audi CS100 Quattro will not start ? Appears to have no spark ? Check engine light did come on ? Does crank?

If the problem is intermittent it would point to a loose electrical connection. I would check your grounds especially at the coil. Even if the battery is fully charged nothing will happen if the ground connection is not made. That would have been evidenced by possibly erratic gages or a wiper motor that seemed slow. The current needed to run the motor would be excessive and open the circuit breaker or fuse because of the bad or usually rusted grounding connection.

Check the ignition control module. Common to fail. and usually is intermittent until it finally quits.