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Poor cold start/idle
I have been trying to get to the bottom of a poor cold start and
poor cold idle problem (88 5kcstq). The symptoms are similar to
the recent thread on this topic. Runs absolutely great once past
the sputtering phase. Have checked like crazy for vacuum leaks
and fuel pressures and am now looking more closely at the idle
Bentley is vague concerning the engine temp switch/sensor
which feeds engine warm/cold info to the idle stab. controller.
The electrical schematic shows a thermo _switch_ with a
single wire. The CIS or CISIIIE chapter also hints at an
idle stab. thermo _switch_ which is closed cold and open above
40 to 60C - but this is shown as a 2-wire connection device.
My car has the idle stab. temp wire connected to a 1-wire
temperature _sender_ which looks like and shows about the
same resistance as the engine temp sender for the ECU.
One of these senders is mounted on the upper coolant hose
flange along with the turbo pump thermo switch and the
multi-temp sender. The other is mounted directly on the
side of the head a bit forward of this flange - near the
steering pump. The Bentley seems to suggest that this
forward mounted sender is the ECU temp source. On the
other hand, the only coolant flange mounted 1-wire device
the dealer shows is a sensor, not a switch.
I have found that the car cold starts much better if I provide
a _switch_ type signal to the idle stab. controller by shorting
the temp signal wire to ground. Questions: is the idle stab.
temp input supposed to be a temp sender (variable resistance
changes with temp) or a thermo switch (on/off)? And which
sensor location is which?
DeWitt Harrison email@example.com