On Thu, 2 Dec 1999, Bernd D. Ratsch wrote:
>
> I'm not sure about the rest of the engine/trans combinations...but my V6 is
> set at 650-700 with a 5spd. (An Automatic will probably be slightly
> higher.)
>
> If the idle isn't where it should be and everything else checks out
> ok...then you should have the dealer take a look at it (if it's under
> warranty). Or...as a last resort...try to set it yourself with the throttle
> stop screw. Since the computers are the ones that ultimately control the
> idle speed, you may find that it will try to set the idle back to where it
> wants it. (Just like trying to change the timing.)
Yep, the throttle stop shouldn't change the idle. That is, if you
move it in, you probably can raise the idle, but the computer will try
to drop it via the IAC. If you actually adjust the IAC in far enough
so that the computer can't drop the RPMs down to where it wants them,
it'll trigger an error code. As I understand it, the idle stop screw is
only a "limp home" measure. What you should do to ensure that its set OK
is to turn the key on (without starting the engine) to reset the IAC,
then disconnect the IAC (at the back of the TB), then start the engine,
and adjust the stop screw to perhaps 500-600rpm. Then, shut off the
engine and reconnect the IAC. If your IAC ever kicks the bucket, the
idle screw should ensure that your truck will idle. Beyond that though,
the idle screw really doesn't do anything. The idle is controlled by the
computer, by moving the piston on the IAC back and forth. If you're
feeling particularly adventurous, and you want to see how useless the idle
set screw really is, let the engine idle, and cover both bores of the TB
with your hands. Almost no suction. Then, stick your hand over the cavity
just behind the throttle bores, and watch your hand get sucked into the
intake manifold! Scared the crap outta me when I did that once! There is
a huge volume of air moving through the IAT cavity; the stop screw doesn't
really do anything as long as your IAC is operational.
-Jon-
.--- stei0302@cs.fredonia.edu ----------------------------------------.
| Jon Steiger * AOPA, DoD, EAA, MP Race Team, NMA, SPA, USUA * RP-SEL |
| '96 Dodge Dakota V8, '96 Suzuki Intruder 1400, '96 Kolb FireFly 447 |
`--------------------------- http://www.cs.fredonia.edu/~stei0302/ ---'
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