does idling drop to a certain rpm as the car gets older or does it only drop if theres anything wrong with the engine?

where do i adjust idling, on the throttle body or the iacv?

thanks.

 

it's a screw on the throttle body just above the butteryfly valve on the throttle body.

and i'm not quite certain on what you're explaining on the idle issue.
please be more specific.

 

oops..sorry.

well, i was wondering that, when i bought my SiR new it was idling ok at 750rpm. now, it's 2 1/2 years old already and the normal idling dropped to about 650-700rpm and i think that's what causing my exhaust pulse to be "vrooo vrooo vrooo vrooo" instead of "vroooooooooooooooooo" while idling. one more thing, when i pressed the clutch pedal then brake pedal to make a complete stop at intersection the idle would drop to about 500rpm then swings back up to the normal idling once the car made a full stop.

so i like to know if these things happening to my car is normal when a car gets older or there's just something wrong with it.

by the way, i've cleaned my iacv before and wasn't aware there's an o-ring on it and i haven't got the time to check it yet if it's still there, will there be any negative effect if i lost the o-ring?

thanks.

 

Your idle is one big controlled air leak...so any gasket needed should be installed, thats why when someone complains of there idle being too high or bouncing around, its typically because there is a vaccum leak somewhere.

Now, I don't know about all throttle bodies out there, but on mine [99Cx, D16Y7] there are 2 screws. One is called the Throttle Stop Screw and the other is the Idle Air Adjustmnt Screw.

From the factory, the TSS should have been set and NOT touched unless you really had to. When messing with this screw, you are in fact changing the TPS voltage as well. It is possible over time that the throttle plate wears some of the bore away allowing some extra air to bypass, which then might need a TSS adjustment, or a new T-Body.

The IAA screw is what lets air bypass the throttle plate IN addition to what the IACV is letting through.

So basically, with IACV un-plugged, you should get the car to idle @ 500rpm's[?]. When you plug the IACV back in, the idle should jump to about 700 or so...whatever the Helms states.

Just remember, the IACV is there to hold the idle in a 'window', and the window is only so big, so you have to adjust your 'base' idle into the window, then let the IACV take over.

**The method DOES differ if your running an ECU that uses a 3-wire IACV, which is really only found on some 96+ models.**

 

Might check your timing, and cam/crankshaft alignment. Sometimes being off a tooth or two, can make your exhaust sound funny at idle....