Re: Idle Air Control Motor

From: BlackDak93 (stephen.barnett@worldnet.att.net)
Date: Sat Aug 09 2003 - 16:14:45 EDT


<jon@dakota-truck.net> wrote in message
news:bh3alt$euv$1@bent.twistedbits.net...
>
> "BlackDak93" <stephen.barnett@worldnet.att.net> wrote:
>
> : I know that the Idle Air Control Motor provides air for the engine at
idle,
> : but can someone explain to me why it opens up during acceleration? I
don't
> : know if it is worse with a high flow air filter or if you just hear it
more,
> : but it sound like sh**t. It sounds like it is sucking it's last dying
gasp
> : of breath. Is the stock TB not allowing enough air in or what? I have
had
> : this happen on two different engines, 3.9 and 5.2, and have replaced the
> : IACM even though it wasn't bad. I'm sure others have experienced this.
I'm
> : about ready to pitch my K&N just because I can't stand the noise. Is
there
> : any remedy for this?
>
>
> It opens in anticipation of the throttle blades being shut after
> the accelleration event is over. (Having the max available amount of
> air flowing through the TB during WOT might be a factor too, but I'm
> not sure about that.) Generally, after you are done accellerating, you
> will let off on the gas, and could potentially let off on the gas all
> the way, completely closing the throttle body bores. However, the engine
> is still at a high RPM, needs some time to wind back down, and is still
> pumping air during that time. Having the IAC open guarantees that
> there is an available source of air should the throttle blades be
> suddenly shut.
>
> An F&B Billet TB might reduce the whistle since it is a different
> design than stock (you'd have to check with Bruce on that
> http://www.fbthrottlebodies.com/), or you could revert to a K&N drop-in
> with the stock intake system. I've never really noticed it on my
> trucks, or if I have, its not a sound that has registered as being
> "bad". Maybe turn up the radio or get a louder exhaust? ;-)
>
>
> --
>
> -Jon-
>
> .---- Jon Steiger ------ jon@dakota-truck.net or
jon@jonsteiger.com ------.
> | I'm the: AOPA, DoD, EAA, NMA, NRA, SPA, USUA. Rec & UL Pilot - SEL
|
> | 70 Cuda, 90 Dak 'vert, 92 Ram 4x4, 96 Dak, 96 Intruder 1400, 96 FireFly
|
> `------------------------------------------
http://www.jonsteiger.com ----'

Thanks Jon for that info. That makes sense, I guess. Actually I did try the
drop in K&N. That wasn't really want I wanted either. I also did go to a
louder exhaust, although not for that reason. I put on a Flowmaster 50 and
now in addition to the annoying sucking sound during acceleration, I have an
even more annoying rumbling and stumbling and backfiring during
deceleration, but that's another story.



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