I hate to give such a ridiculous answer but if you've removed the black plastic spash guard/heat shield from underneath the engine while working on it you may want to put it back. i could help a little bit. That is, assuming that your model comes with those. I've never work on a 90 civic before.

 

LOL
I don't think that's going to do anything...

 

ya, I suppose not. but everybody else had already taken all the good suggestions.