Ok guys here the story: My 88 CRX Si is Idleling funny. This just started last week. After if warms up it starts to iddle erratically. It goes up to about 1500, and then drops to about 800. It keeps doing this, but the car can still run. I have since taken it to the dealership and they dont' know why it's doing this. Someone please help me!
Thanks.

 

-make sure your coolant system is full
-reset your idle

That's pretty sad that the dealer didn't know how to fix it.

 

That's what I'm thinking. They've had the car for a week now, and they still don't know.

 

your fast idle valve is screwed

 

Common causes of an erratic idle..

1) Coolant Level

2) TW Switch

3) Fast idle control valve

4) Intake air control valve

I would rule out #1 and #2 to the fact it surges when the car is already warmed up and not when its cold.. the mentioned valves can sometime be diagnosed by re-creating the surge and then lightly tapping on the solenoid to see if the problem goes away..

 

my gf's 92 civic had the same problem
it was a gasket that caused it, i wanna say intake but not sure

 

Throwing any MIL codes?

 

What's a MIL code???

 

You may have a vacuum leak somewhere. Check around your intake manifold for air leaks. And check all your vacuum lines for leaks.