i have a 92 accord wagon, when you first start the car up the rpm's raise a little till the car warms up. once the car is running for a while , the rpm's begin to raise and drop quickly between 1,000 and 2,000 rpm's . then it goes away and comes back after a while when you come to a stop while driving. So, i was wondering what may cause this to happen. any input would be great!!! thanks in advance.

 

i had the same problem but in my 00 bmw...there was low psi in the cylinders...could be that...if thats the case you can get stuff called RESTORE and mix about 2 cans of that in with an oil change. ... do this again after about 1k - 1500 miles then after that at 4k more....

before you do that get the cylinders psi checked out...

or like someone else did with the same problem, you can clean the throttle body i think it was....there is another thread like this one, check it out.

 

sounds like you ivac is starting to go. also you might check for vaccuum leaks.

 

i had the same thing happen to my coupe... its either the fitv ( fast idle thermo valve, tighten the plunger) located on the throttle body, the iacv (located on the intake manifold, you can clean this), or a vaccum leak

 

yep

 

agreed idle air control valve or something of that nature, like dude said you have the little black circle on the intake manafold/throttle body you can use a flat head and rotate it clock wise or counter and it will increase and decrease your idle, that did it for me

 

agreed

 

x3 on the IAVC or other vac leak.

 

thanaks for the help guys i will look into that this weekend

 

low coolant will do that to but mostly likely iac