Subaru TBI

[Bernd Felsche]

John Dammeyer writes:

>>dzorde at erggroup.com writes:
>>>On a different note.  I just picked up a Subaru TBI (centre point injection,
>>>think its of a 1.8L import motor), the injector is a 1.6 ohm unit.  Can someone
>>>tell me if this has to be driven as P/H or whether it can be driven as saturated
>>>(if so does it need a resistor ?)
>>
>>No resistor required. Injectors are normally driven by sinking
>>current through them; no "ballast" required. The duty cycle of
>>pulsing determines the flow.  No fancy timing requirements.  It's
>>just a cheap way of implementing an electronically-controlled
>>carburettor. ;-)

>Yikes!  or How to screw up an injector in one easy pulse.

>This is a PeakHold type injector.  13.8V / 1.6 Ohms is almost 9 Amps.  Injectors normally
>don't take more than about 1A.  You have a choice on how to drive a PH injector.  You can

OOPS. Sorry. It's just me jumping in without understanding the
question entirely. I have (obviously) yet to learn the vagaries of
PeakHold. Looks like I've mis-understood something previously.

Consider me castigated.

>Only if the injector resistance is around 12 Ohms can you apply 12 volts directly to it.

My cursory study of the 332 drivers indicate 4A to be a typical
drive current. No "ballast" resistors were shown on the schematic -
though there is current sensing which I now understand is to control
the peak current.

-- 
Real Name: Bernd Felsche
    Email: nospam.bernie at perth.DIALix.com.au
     http://www.perth.dialix.com.au/~bernie - Private HP
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