Thermo-time-switch/ cold start valve- poor running

[Aaron Ryba]

Ti,

If there were a faulty ground between the
thermo-time-switch and the cold start injector would
not the injector be "running" when the ignition were
at run and not at start?

If so, what would be the side effects of the cold
start injector spraying fuel into the intake manifold
when it was not needed. Overly rich fuel mixture? Poor
combustion? Possible pre-detonation inside the intake
chamber?

It sounds like there is a force slamming the air
intake plate, some force traveling back from the
intake manifold.

Where exactly is the thermo switch that informs the
ECU located? Atop the coolant/thermostat housing? Or
below it? (I-5 engine)

Thanks for the advice. I will perform the Bently
procedures shortly.

--- Ti Kan <ti at amb.org> wrote:
> Aaron Ryba writes:
> > What function does the thermo-time-switch have?
>
> Controls whether the cold start valve should be
> activated during
> cranking, and the duration of its activation.
>
> > Does it control the cold start valve? The valve
> only?
>
> Yes.
>
> > Where exactly is it located? (toward rear of
> head?)
>
> On an I5, on the back of the head.  On an I4, on the
> top
> radiator hose flange.
>
> > Of what temp does it monitor? (Coolant?, head
> itself?)
>
> The bi-metallic element inside the switch, which is
> heated by:
> 1. The internal electrical heating element
> 2. temperature of the coolant and the head
>
> > What is the cold start valve? Is it just an extra
> > injector, electronically trigered?
>
> Yes.
>
> > Where does it spray extra fuel and when?
>
> During cranking (ignition key in the "start"
> position)
> and only when its cold enough (controlled by
> thermo-time switch).
>
> > Into the mechanical fuel dist.?
>
> No.  Into the intake manifold.
>
> > For a while I have experienced a sporatic poor
> running
> > condition of my 87 4kcsq. Symptoms include very
> rough
> > idle, extreme loss of power, sulfer-esk smelling
> > (exhaust?) odor, misfiring-like noise and noise
> from
> > air pressure plate slamming. This only happens for
> > about 10 seconds at a time and happens
> sporatically
> > sometimes during warm-up, most often during
> highway
> > cruising. Often happens when engine temp is low
> but
> > not always happens.
> > The car never has a hard time starting though,
> cold or
> > warm.
> >
> > I am thinking a faulty thermo-time switch, cold
> start
> > valve or a ground in the wiring between the two
> might
> > be the problem.
>
> No.  Once the engine starts to run (your ignition
> key
> is returned to the "run" position), the thermo-time
> switch
> and the cold start valve are no longer active at
> all.  These
> are cold *starting* aid devices, not cold *running*
> aid.
>
> Check the temperature sender that feeds the CIS-E
> control unit.
> You should also check for air leaks, and diagnose
> the problem
> using the procedures outlined in the Bentley, such
> as checking
> the oxygen sensor, basic fuel pressures, fuel air
> mixture,
> differential pressure regulator current, etc.
>
> -Ti
> 2003 A4 1.8T multitronic
> 2001 S4 biturbo 6-sp
> 1984 5000S turbo
> 1980 4000 2.0 5-sp
> --
>     ///  Ti Kan                Vorsprung durch
> Technik
>    ///   AMB Laboratories, Sunnyvale, CA. USA
>   ///    ti at amb.org
>  //////  http://www.amb.org/ti/
> ///
>


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