RE: [DML] high idle at start up

["John Hervey" <john@xxxxxxxxxxxxxxxx>]

Andy, you would have to look at the valve in the bottom of the idle speed
motor to see if it's opening. It may not be and that's why it chocking down.
John Hervey
www.specialtauto.com




-----Original Message-----
From: Soma576@xxxxxxx [mailto:Soma576@xxxxxxx]
Sent: Sunday, May 02, 2004 7:22 PM
To: dmcnews@xxxxxxxxxxxxxxx
Subject: Re: [DML] high idle at start up


In a message dated 5/2/04 10:02:49 AM Central Daylight Time,
advantics@xxxxxxx writes:


> My baby starts now, but idles a little high at about 1200 rpm. It
> will run fine for a few minutes  then it gets a little ruff and then
> wants to die if you don't give it gas. I tested the idle speed switch
> and it is working. How do I tell if the idle speed motor is working
> or not? Thanks in advance.
>
> John 5326 & 1383

the idle speed motor should be purring like a kitten while the car is
running.
how did you test the idle speed switch?
sounds to me like either the control pressure regulator or the idle speed
motor are stuck, or you have a vacuum leak that gets worse as the car warms
up
until the car won't stay running anymore.

here is what you should do:
1.  first check the idle speed switch by removing it from the car and
putting
it on a multimeter (it's hard to test with a meter on the car).  make sure
the meter shows open and closed.  with the pins on the switch, try tapping
the
switch with a wrench in both the open and closed position. if the needle on
the
switch wavers at all, replace the switch.  it is probably intermittent.  the
switch isn't your (whole) problem anyway though.

2.  with a good idle speed switch installed, turn the key to the on position
in your ignition and move the throttle so it makes the idle switch trip on
and
off.  do you hear a dull clicking coming from the back of the fuel
distributer (the ignition advance solenoid )?  if not, you need to get that
fixed or
else your car will experience ignition advance when the car is fully warmed
up.
check all of your vacuum hoses and make sure they are routed correctly.  any
questionable hoses should be replaced.

3. when the car is running, try spraying some starting fuel all around the
engine, listening for engine changes between squirts.  this can help you
pinpoint a bad vacuum leak.  concentrate on the driver's side of the engine
where all
the vacuum hoses and the idle speed motor piping are.  the passenger side
won't have any leaks unless the manifold isn't sitting properly (and then
the car
probably wouldn't run!).

4.  while you are at it, if you are sure the car isn't getting ignition
advance at full temperature, check your timing.  that won't solve the
problem but
it could help smooth things out.

5.  if you have a fuel pressure gauge (specially for Bosch K-Jet), you may
want to install it while the engine is cold and then observe your control
pressure as the engine warms up.  perhaps your CPR is dead?

sounds to me more like you have a dead idle speed motor, bad wiring for it,
or a dead idle ECU (rare). it is maybe stuck in an open (higher) position,
which lets more air than is necessary upon start up.  then as the engine
warms up,
the air doesn't change in relation to the fuel (from the CPR) and it kills
the motor.   remember - your 'gas pedal' isn't a gas pedal - it's an AIR
pedal -
when you hit the gas, the car runs better because you just cracked the
throttle - the only other way for air to get into the motor. i might be
wrong but
that makes sense to me.

Andy


[Non-text portions of this message have been removed]




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