i have a 00 prelude and it idles like crap.....i haven't removed any parts in the intake manifold.....i think it's a vacuum leak somewhere...and by the looks of it, it seems like a HUGE leak

i've checked all the vacuum hoses from the ports and i don't think that's it. and because it seems like a huge leak, it's gotta be more than a slit in a hose. but nonetheless, i've removed the hoses and plugged up the holes to troubleshoot and it's not that. i also checked the IAC and that's not it. my friend said it could be a thermal idle control valve stuck open. anyone else have ideas?

thanks!

 

Define 'idles like crap'

How does it idle? What are the exact symptoms...maybe then someone could help.

 

hum...did you try to adjust the throttle cable?

 

crap like:

without touching the throttle and after cranking the engine on, the engine would surge from 500-2000rpm up and down and won't stabilize

 

u sir, have a bad idle control valve

 

yea...that's what i originally thought, but i replaced it with a working one...and still the same symptoms...any other ideas?

 

adjust ur idle, it normally does it when its set too high or too low

 

adjust it with a stock ECU? what should i adjust? i think it might be a mechanical problem

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cowboy &raquo;</TD></TR><TR><TD CLASS="quote">yea...that's what i originally thought, but i replaced it with a working one...and still the same symptoms...any other ideas?</TD></TR></TABLE>

You replaced the "fast idle thermo valve"? Cause that was the exact problems on my friend's.

 

ok, let me get this straight...

are there 3 idle control valves? or am i totally confused?

1) Idle Air Control Valve (thing usually in plain view, between engine and intake manifold, connected with coolent and wires)
2) Fast Idle Control Valve (for preludes, under throttle butterfly, dependent on coolant temp and turns on for quicker warm up)
3) Thermal Control Valve (for preludes, opposite end of the intake manifold from the throttle plate, have no idea what it does)

i'm totally guessing what these things do, and i'm not sure if these things actually exist, or am i making it up?

 

anyone have ideas?

thanks!

 

anyone?

 

Check that TPS is set to 4.5V @ WOT.

 

I had the same problem as you. This however pertains to my B18B. Anyway, I got to the point where I was fed up with mine so I did some research. Heres what I did and I can notice a difference in my overall idle quality already (no more surging, better stabilization). I removed the fast idle thermo-valve, located right underneath the throttle body, has two coolant lines going to it and is held in by three 10mm bolts. Removed that, then on the one end, there is a small oval plate held on by two 8mm bolts. You'll see the white piece of the valve that can be threaded in. Thread that in as far as it will go with a flat-head. Reinstall. Crank the heater to full blast, take off your radiator cap, and start your car (better if its cold). Let it warm up. Once warm, any air in the cooling system should have made their way to the cap area. Put the cap on. With the car running, unplug the connector that goes to the IAC on the rear of the throttle body. The idle should drop and stablize pretty low. Turn off the car. Reconnect the plug for the IAC. Pull the 7.5 back up fuse for at least 10 seconds. Put it back in. You've now reset the ECU. Start the car, warm it up and drive. Come to a stop and see how it idles. This might not work for everybody's hunting idle, but it dramatically helped mine.