does this sentence make sense?

He had to leave the park soon because he left his three cars' engines running.

No

"had" is past tense
"soon" is future tense
"left" is past tense
"soon" needs to be changed to future tense for the sentence to make sense

sorry i meant "soon" needs to be changed to past tense

Or simply remove “soon”!

Yes, the sentence "He had to leave the park soon because he left his three cars' engines running" does make sense. It implies that the person had to leave the park quickly because they had left the engines of their three cars running. However, it's important to note that leaving car engines running for an extended period is generally not advisable as it can waste fuel and contribute to air pollution.