So on my 96 accord, when I first start the car and give it a few minor revs. The RPM's begin to jump from 1 to 2 over and over again?

Anybody have any idea what this problem could be?



And second when driving and on the accelerator the car makes a near lawn mower sound? I believe this might be a exhaust leak?

Any idea's about that?

 

Well about the revs, my 99 accord [200k miles] does the same thing... I'll start it cold, then rev it lightly, but then the rpms dip down to 1k then back up to 1700 or so. Engines normally idle a bit higher when warming up.

About the lawnmower sound, if it is coming from the front of the engine, it's probably with your intake. Aftermarket intakes and/or bigger air filters let more air in, but it growls at any rpm beyond half throttle, and progressively gets louder and high pitched at as you climb the revs. SO- check your intake, and if something looks loose or detached in there, then fixing it will take away the lawnmower sound

Now, if it coming from the back of then engine, check the exhaust. At idle, you might hear a hissing sound like a leaky tire, and that is an exhaust leak for sure.

 

Pull off the IAC valve on the back of your intake manifold and see if it's clogged up (2 12MM bolts and two coolant hoses). You can try to clean it out with throttle body cleaner, but it's easier to replace it.
You probably have an exhaust leak somewhere.