Re: [DML] high idle at start up

[Soma576@xxxxxxx]

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


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