I just picked up a 2000 honda civic lx. D16Y7 unmodded
Car had a bouncing idle, put my finger over the throttle body hole for the IACV and stopped... easy fix just clean or get a new one ( i might add I did have check engine light on 02 sensor, and IACV or MAP ce. In any case, went to the wreckers, picked up a whole throttle body with sensors $20 ( i love red neck junk yards). Put the new one on, and remembered it came from an automatic ( mine is 5 speed) so i ended up just cleaning the old one. Reset ecu, only check engine code is the 02 sensor, my buddy said has been on for years, even after he replaced sensor. As of now:

Idle is still bouncing
Car heats up fast, but doesn't overheat
Thought there was oil in coolant overflow, but i think its just grease around the rim.
When opening the rad up, level pulses up and down ( not bubbling ) i am assuming this is normal when rpm level is going up and down
I was thinking head gasket ( thats friend-ending if it was)
Compression tested tonight, 180ish all acrossed the board
I need something to go off of guys, i'm at a loss here. I'm in ontario, and I have like 13 days left on my trip permits ( i'm also wasting valuable insurance not driving it)

Help me please!!!!!!!!!!!!!!!

 

Did you check for vacuum leak? Try replacing TB gasket. Also, try to flash the radiator. Check to see if thermostat is working properly.

 

Use some carb cleaner on the vaccum hoses/TB area.
If you hear it surge you have a leak.
Trace and replace the hose as needed.
IACV can cause a bouncing idle. There are lots of posts on that. search for that beast.

Bad TB? they go bad ,and dont close all the way, can cause the idle to surge, and bounce.
Push on the throttle body spring area, sometimes that is an indicator or a bad TB. Rotate it back as if you are forcing the tb closed.. See what happens...does it stop or settle down?
Replace the 02 sensor and get that Cel cleared.
Insurance is the least of your worries right now. its fixing and making reliable that you need to concentrate on.

 

Ive been chasing a bouncing idle for a few months now. Ive cleaned or replaced the IACV, FIAC (I know y8s have them idk about Y7s. Basically its a valve that creates a controlled vacuum leak when the cars cold to heat up the O2s.), evap purge solenoid (Can stick causing a small vacuum leak at idle), PCV, upstream O2 sensor, MAP and the ECT. And its still there. Its gotten a ton better but its still there. My next thing to check is my load detector because Ive been throwing a VSS code from time to time. Hope that gives you some stuff to check.

 

Just an update guys...after cleaning it didn't work...and I tried blocking the hole and nothing. Out of some sort of rant and rave, I decided to put the whole throttle body I got from the wreckers on it..and still doing the same thing. This time i covered the iacv hole, idled fine ( well low but fine). Right now so I can get to work, I have the hole covered with some sheet metal tape. Ordered new IACV should be here this week. On a side note, i found out that the cooling fan was not turning on and thats why the car was getting hot. Checked the fan it works fine, jumped the fan switch didn't turn on so i suspect the relay is gone.
In any case, this car is as ghetto as it gets right now...but its running and I can drive it!!!

 

i have the same problen with my y7 iacv, but i swaped it with another and still have the same idle problem

 

have you tried lowering the screw on the throttle body,, once you lower the idle,, it might stop bouncing up and down.. common honda problem..

 

What happened when you did this^ test?

 

cover up the fast idle on the inside of the throttle body, & check throttle body gasket

 

OP, you say you cleaned your IACV, what exactly does that entail? Spraying carburetor cleaner in there and doing nothing else isn't exactly "cleaning". You've got to remove the IACV from the throttle body completely, then clean the rotating cylinder with a q-tip and carburetor cleaner. Try to rotate the cylinder with your finger, you might find it's "stuck" which if it is, you need to 'break it free' so that it rotates. Clean thoroughly so it moves around smoothly.

 

I had the exact same symptoms... I cleaned the IACV and it worked for about a week. Then the slight overheating continued.

So i conducted a leak down test, and needless to say it was a blown HEAD GASKET.