dem0nk1d

Is there any way to fix the boucing idle with the Throttle Body coolant lines capped off? I know the ecu adjust to the sensors located on the throttle body.

-Gary-

I did the same exact thing on my first Si and had the same problem. I haven't tried it again on my new one but here's what I found when I started poking around the Internet trying to find a solution. I'm not sure how the same a Prelude TB and a Civic TB are, but the discription of what he does to fix the surging issue is written pretty well.

http://www.92lude.com/idle_air...d.htm

EE_Chris

Did you re-bleed the coolant system after doing this?

dem0nk1d

there would be no coolant lines now to bleed that return to and from the throttle body.

EE_Chris

Was the idle fine before messing with the coolant lines?

mrbigg9032

That shouldnt effect idle at all. The only thin the coolant lines in the TB do is warm up the TB faster in the winter. Idle has absolutly nothing to do with it. Check you idle air control valve. A bouncing idle sounds like a vacuum leak.

dem0nk1d

Yes idle was perfect before taking the coolant lines off the throttle body. I will post pictures... When i get time.

SkankyEJ7

yeah i dont thin it really has much to do with the idle, but my car does it, but im pretty sure i have a leaky tb gasket

EE_Chris

When you took the coolant lines off of the throttle body, did any coolant spill out of them?

tpr

On the bottom of the throttle body is the fast idle control. It has coolant lines so in and out. As the coolant tempertaure rises it makes a wax pellet close to the normal "warm idle" air flow. The ECU is trying to compensate but has a limited adjustment range. As a result the IACV is moving to its limit but the idle is too high and then the ECU shuts off the fuel. The idle drops quickly then the ECU turns back on the fuel and the cycle repeats.

Why did you want to stop coolant from going through the throttle body in the first place?

tpr

On the bottom of the throttle body is the fast idle control. It has coolant lines so in and out. As the coolant tempertaure rises it makes a wax pellet close to the normal "warm idle" air flow. The ECU is trying to compensate for that but has a limited adjustment range. As a result the IACV is moving to its limit but the idle is too high and then the ECU shuts off the fuel. The idle drops quickly then the ECU turns back on the fuel and the cycle repeats.

Why did you want to stop coolant from going through the throttle body in the first place?

-Gary-

The cooler the intake charge the better. It doesn't really make up that much of a difference though in my opinion. F-Body and Mustang guys have been doing this for a long, long time at the track.

Gadget

do yourself a favor..

remove the throttle body, and check to make sure the gasket you're using correctly outlines all passages on both intake and throttlebody..

Directions for locking out the Thermal IAC valve assy:

1) Remove the water snout from the Thermal IAC valve (2 screws) and remove the wax pellet assy just like it was a bolt..

2) Remove the cover plate from the other end of the Thermal IAC valve, and unscrew the white nylon valve seat but not all the way, using a flat head screw driver in one of the 2 slots, try not to damage it..

3) Screw a spare distributer bolt into the hole where you removed the wax pellet, if you feel tension on the bolt before it bottoms out, you need a shorter bolt..

4) The bolt should bottom out and lightly snug it..

5) On the other end, (Valve side) tighten the white nylon valve seat until the valve in the center of the seat cannot be depressed.

6) Reinstall the cover plate and bolt the throttlebody back on the intake..

(The whole point is to remove the wax pellet assy and replace it with a bolt to lock the valve in the closed position)

7) Set the TPS.. if you have screws on your TPS, GOOD! If not, you need to take a dremmel and cut slots in it so you can kinda make the safty bolts accept a flat head screw driver..

8) loosen the 2 screws on the TPS, turn the cars ignition to "ON"... Using a digital multimeter probe the wires (I don't remember the colors) ground one terminal of the multi meter on the battery.. with the other probing the 3 wires on the TPS you will read 0v (Ground) +5v (Refrence) and +~.35-.60v (Signal to the ECU) This is the wire you want to read..

9) With the TPS loose, and ignition ON, rotate the TPS to obtain a reading of .40-.50v (Factory honda spec is .45v) the closer to .45v you can get it, the better.. Now tighten the TPS and it's set..

10) (After the car is warmed up) Remove the plug from your IACV on the back of the intake and start the car.. Try to get it to idle.. using the air bleed screw on the throttlebody (Brass screw on top by the MAP sensor) adjust the idle to ~450 RPM.. shut car off and plug in the IACV..

11) Adjust timing to 16* after jumping the check connecter, remove jumper and your car should run perfect..

Gadget

I forgot to mention...

The reason to remove water from the throttle body AND the IACV is the same reason that Hond@ta sells those insulating intake gaskets.. to cool the intake.. If you remove the HOT coolant from the intake, you get a cooler, denser air intake charge and make more power.. Of course because the air is cooler you also burn a little more fuel, but whos talking gas mileage when you have a honda?

it was basically a provision to keep the IACV and the throttlebody from freezing (Which mine has never done while the coolant was disconnected) and emmisions reasons, (partially because the engine consumes less fuel with a warm intake charge)..

dem0nk1d

You da man!