What is the participle adjective in the following sentence?: The funny sound coming from the car was very alarming.
This is not a participle here by functioning reason.
Let us check by grammar morphology.
"The funny sound coming from the car was very alarming."
The ( Determiner adjective) +funny ( pure adjective)+ sound ( by functioning here an adjective not a noun)+ coming ( functioning a noun here by GERUND form)
+ from ( a preposition)+-----
And by rule of thumbs of grammar says, you will not have any single word "subject" after the preposition.
"The funny sound coming from the car"
The subject of the sentence.
"coming" the subject of the verb.
Keep in mind, subject is always a single noun.
( More? Better English by Norman Lewis, an ex professor of English in New York university)