1987 Honda Idle Prob

Son has a 1987 Honda,Prelude that won't idle right it surges when idleing ,It will speed up and slow don't when sitting at a idle and will do it steady as if some one is pushing on gas and letting up non stop,does not do it if gas pedal is depressed a little and it is kept at a higher rpm

 

I would start by looking for a vacuum leak. Also check the PCV line and valve. The bottom line to surging is usually something that creates an overly lean mixture. That leads to the mixture burning too quickly and sporadically.

You might consider a vacuum gauge to chase the problem. They're cheap and a pretty good diagnostic tool. They come with a number of symptoms to look for in the instructions for using them. Vacuum leaks and valve problems are a couple of the things they uncover.

There are fewer people using them on the newer vehicles, though, with OBD codes and different electronic tools to chase problems with.

Hope this helps,

Bob