i have been trying to figure this thing out for too long...and it seems like it could be anything at this point. so now i must turn to my fellow h-t members. i have searched however it seems like everybody has a slightly different situation on there hands!

here's the problem:

when the car makes it's first cold start of the morning the idle is super high (around 3,500 maybe even higher). during the warm up the idle is smooth, lol. once the motor gets warm the fun begins as the car drops down to about 1,000 rpm then starts surging up to about 1,500 rpm. i have also noticed a loss in pressure in the brakes as i sit at stop lights. i checked the brake booster by removing the hose and plugging it and my idle problem did not change...i then proceeded to remove my charge pipe as it was running and plugged the top hole in the throttle body and my idle problem went away! i also tried plugging the bottom one and the car proceeded to shut off. at this point i thought it was the idle control valve on the back of the intake mani...so i changed it...i then started the car again and my idle problem was still there! FAWK!!!!

let me know if you need more info...
any and all help would be awsome peeps, thank in advance!

 

 

i have the SAME EXACT problem, idles high when cold, then drops down. what could it be?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chpt1onBOOST [DMV &raquo;</TD></TR><TR><TD CLASS="quote">]i have been trying to figure this thing out for too long...and it seems like it could be anything at this point. so now i must turn to my fellow h-t members. i have searched however it seems like everybody has a slightly different situation on there hands!

here's the problem:

when the car makes it's first cold start of the morning the idle is super high (around 3,500 maybe even higher). during the warm up the idle is smooth, lol. once the motor gets warm the fun begins as the car drops down to about 1,000 rpm then starts surging up to about 1,500 rpm. i have also noticed a loss in pressure in the brakes as i sit at stop lights. i checked the brake booster by removing the hose and plugging it and my idle problem did not change...i then proceeded to remove my charge pipe as it was running and plugged the top hole in the throttle body and my idle problem went away! i also tried plugging the bottom one and the car proceeded to shut off. at this point i thought it was the idle control valve on the back of the intake mani...so i changed it...i then started the car again and my idle problem was still there! FAWK!!!!

let me know if you need more info...
any and all help would be awsome peeps, thank in advance!</TD></TR></TABLE>

sounds like a vacuum leak. check ALL YOUR HOSES!!!

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gsrcivic619 &raquo;</TD></TR><TR><TD CLASS="quote">i have the SAME EXACT problem, idles high when cold, then drops down. what could it be?</TD></TR></TABLE>
its NORMAL for the car to idle high (1500ish) when you first start it, then when the car warms up it drops back down. its so the engine gets up to operating temprature quicker.

 

i have checked them a few times, even fixed a few of them...still got no result...

oh yeah the car throws no codes either!

 

Try replacing ALL of your intake manifold gaskets...Over time they can get soaked in oil from the PCV valve and deteriorate....Worked for me

 

What engine are you dealing with?

At the end of the day, your engine should be able to idle on its own without the use of a IACV (or FITV is so equipped). The idle air bypass screw (on the throttle body) should be set to allow enough air into the manifold to get the engine to idle at ~500rpm.

So on a warm engine, unplug the IACV; What does the idle do? If you have a FITV, and its leaking air (as it shouldn't be on a hot engine), plug the bottom hole in the throttle body. What happens to the idle now?

After the IACV is unplugged, and FITV hole plugged as well, your idle should be ~500rpm. If its above this, there are a few possible causes: throttle plate stop screw messed with, thus affecting TPS output; air in the coolant system; vacuum leaks.