Idle problem

[Samabra]

Hey guys, I'm very close to finishing my project, but I have a slight problem. I have an SR20DET S13 Redtop, with a Trust TD06 turbo, lightened flywheel and 850 CC injectors. The problem is that you start it, and it will idle between 1200 and 2100 RPM, however sometimes it will go away if you put it in gear, and you can drive it just fine. The ECU was modified for the turbo, and upgraded injectors, so tomorrow I'm going to try a stock ECU and see what happens. But any suggestions would be appriciated. Thanks Chris

[MadSideways]

I have the same problem. My idle bounces between 1500/2000rpm every 2 seconds, but drives just fine.

I would like to note that this occured after I installed my greddy intake plenum. So my first guess is that something's fishy with the IACV.

However, if that doesn't seem to be the problem I'll try replacing my o2 sensor and cleaning the MAFS.

[compression]

dont forget about the fast idle thermo valve. It is part of the idle motor enclosure on the intake manifold. You run water to it and it closes when the water reaches a certain temperature. Maybe there is an air pocket in that line, and water is not making it to the valve, just a thought.

[MadSideways]

I did a search for 'fast idle thermo valve' and 'idle motor enclosure' and came up with nothing.

However, there are coolant lines running through the IACV, (idle air control valve). Which I have connected....How would I know if there is air in the lines, and how would I go about removing it?

Also, I know people that disconnect them altogether and it still runs fine. They say that it's only needed to heat up the IACV in cold weather climates, the same reason the throttle body has coolant lines running through it.

[compression]

Your search was unsuccessful most likely because I made up those terms, I am not sure what the official names are, look in the fsm.I ran mine without the water lines hooked up to the idle motor. It would not idle below 1050 RPM, even with the idle motor shut. I am using a stand-alone and have complete control of this, thats when I discovered that the valve needs water to close an auxilary passage that the air is let through.After taking 10 minutes to plumb the water through that valve, it now idles at 800-850 RPM when warm with no changes to the software. So it did run fine without that water line the 10minutes of work and 16" of 5/16 hose was worth the lower idle speed to me.I understand that the water is plumber through the throttle body to keep condensating moisture from freezing in cold climates, which may effect evaporative emissions or something else.

As far as checking it for air bubble...disconnect the water line and while you are filling, wait for water to come out of it, then put it back on, thats the best I can think of. I am not sure if this location is prone to air trapping, just a thought.

[180crafter]

Can this passage be modified so that the line does not have to be run??? What would you recommend. Tanks.

[compression]

if you did ont run coolant to it, your idle would not drop below 1050 (or so) rpm.If you remove the idle control motor from the intake manifold you will see that the water temp activated part is very deep inside one of the passages. You could probably fill a passage with RTV silicone to prevent air from ever getting by.

BUt I dont think that you should de-activate it. You would probably have difficult cold starting, crappy cold idle and maybe some other low-rpm issues. It is really easy to run water to it, shouldnt take more than an hour of work, maybe less.

Seems like it would be more trouble to remove it than to just plumb water to it.