I have a JDM D15B VTEC, and the D16Z6 ECU USDM. The car idles around 2k rpm at start up, and then goes down after a bit to around 800 and drives normally. I know the car has a fast idle mechanism controled by a thermowax plunger and when its cold the valve is open and when its warm it closes. Is it usually normal for it to start up at 2k rpm, its that good? Or do you think its a ECU problem? A honda guy told me that it might be a water temp sensor or a air pocket in my coolant? Any ideas?

 

<tossing idea in the air>

My 95 EX runs at about 1500 on warmup, then drops down to maybe 500 or so after its warm.

I'd say that you're probably ok, but the throttle cable might need to be adjusted a bit.

 

is the P28(D16Z6 ECU) unchipped?
2k is a little high. where is your timing set? is your check engine light on?

 

It should be ~1500 on cold startup, ~750 when warm. Adjust your warm idle to spec if you can, that's the best place to start.

 

^what he said.

 

Make sure your base timing is correct with the motor warmed up, then adjust the idle screw on the throttle body. There should be a sealant that's applied all over the screw if it's never been monkeyed with, just scrape it all out with something sharp, then goop some silicone back over it with your finger when you're done adjusting it and it won't leak.

Check your timing again. One adjustment affects the other.