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The 4AGE Cold Start Injector System...

Posted: Sat Jan 17, 2015 2:28 pm
by jondee86
The 4AGE cold start injector system is based on a single injector fitted
to the engine side of the intake plenum. It is fed from the fuel rail and
the the injector solenoid is switched ON and OFF by the starter circuit.
Operation of the cold start is independent of the ECU.

Here is the injector out of the plenum...


To prevent the cold start injector operating once the engine is up to
normal operating temperature, there is a thermo-time switch fitted
at the rear of the head next to the ECU water temp sensor.


The green one is the ECU water temp sensor, and the brown one is
the cold start injector thermo-time switch. The time switch contains
a normally closed contact mounted on a bi-metallic strip. When the
water temp is low, the contact is closed and the cold start injector
will operate while the engine is being cranked (and only when being

If the engine has been running and the water temp is normal, the
contact will be open and the cold start injector will not operate as extra
fuel is not required. There is also an electric "heater" on the bi-metallic
strip that operates during cranking. If the engine does not start after
prolonged cranking, the heater will cause the contact to open and
prevent the cold start from continuing to operate and flooding the

The injector is not "pulsed". It just receives 12V to keep it open while
the engine is cranking. It can be tested by pulling the injector out of
the plenum, putting the end into a clear container and cranking. Use
caution and keep a fire extinguisher handy.

Cheers... jondee86