What causes this?

[MoDawG]

I know this doesn't apply to a 3G but hey it's still an Accord.

I was looking at a 92 Accord LX the other day. When the guy started the car (it wasn;t started in like a week). It idled around 1500 for a bit then started jumping up to just under 2000 and back down. It kept going up and down. What is the cause of this?

[mouchyn]

vacuum leak somewhere.

worn fast idle valve, leaky gasket, bubbles in the coolant, idle set too high, etc.

[ICEMAN707]

it's a messed up fast idle valve. same problem i just had.

[Slipknotcraig133]

My 86 accord lxi was doing that and i checked out every vaccum line till i found one that was cracked and i replaced it and the problem was fixed.