Injectors and resistors

[Mos]

Why dont u build up a current limited injector driver?
Something along those lines:


       ----+--- 12 Volts
           |
  5k6      C
+--R--+--B<   2N3055
      |    E
      C    |
BC337  >B--+
      E    |
      |    R 0.22ohm
      |    |
      +----+
           |
        INJECTOR
           |
          GND

Where BCE are NPN transistors of the type specified. The left side of the
5.6kilo ohm resistor goes to the injector output of the ECU. This circuit
will limit the injector current two approximately 3 amps. IE when the
voltage accross the 0.22 ohm resistor reaches 0.65 volts, BC337 will turn
on reducing the drive to 2N3055, thus limiting the current.

By the way, I have no idea if that's all the injector needs. If it's more
then one coil then this circuit most probably wont work. This circuit was
not tested by me in this application. Confirmation/criticism of the above
is welcome.

Hope this helps.
Mos.

On Mon, 23 Nov 1998, Steve Lamb wrote:

M>I need the assistance of and EE......
M>
M>My next major project is to get an 808 ecm to drive a Nissan VG30DET
M>engine.  This a 3L Quad Cam 24V single turbo engine.  We believe we can
M>solve the main hardware issues to overcome (TB's and ignition system), but
M>one issue remains a thorny one...low impedance injectors (6, to be exact).
M>
M>I'm reliably informed that the 808 will not drive 6 low impedance
M>injectors.  One alternative would be to change the injectors, but this
M>would add quite a bit to the cost.  Another possible alternative is to try
M>what Nissan did with its early L-Jet based systems......use a resistor in
M>series with each injector and thereby increase the total load (?) seen by
M>the injector driver.
M>
M>Can anyone see why an 808 ecm would or wouldn't work when used in this way
M>??   I was thinking of using 6 Ohm resistors, which is what Nissan use in
M>conjunction with their 2.5 Ohm injectors.
M>
M>Thanks
M>
M>
M>Steve Lamb
M>Department of Defence, DSTO
M>Aeronautical and Maritime Research Laboratory
M>506 Lorimer Street
M>Fishermans Bend  VIC 3207 Australia
M>
M>Tel: +61 3 9626 7525
M>Fax: +61 3 9626 7089
M>
M>IZCC #180
M>
M>

--
+----------------------------------------------------+
|           Jealousy is a lifelong curse...          |
|     Reality is the only obstacle to happiness.     |
|              Taciturnity is aurous.                |
+----------------------------------------------------+
| Lukasz Szymanski,                       /\/\OSFET  |
| 3rd Yr, BE(Comp)/MBiomedE                       |--+
| The University of New South Wales            __||<-+
| Email: s2193387 at cse.unsw.edu.au                 |--|
| Web: http://www.cse.unsw.edu.au/~s2193387/         |
+----------------------------------------------------+