Nissan Injectors....what gives ??

[Stephen Lamb]

>A couple query's. What size ballast resistor are you using and are you
>running the injectors in parallel or in series or are you using a separate
>driver for each. The ballast resistors are there to stop the computer from
>over heating. The most common way  to wire up the ballast resistors is in
>parallel. This will give a total resistance of .625 ohm's. When supplying
>12 volts across this you end up driving around 20 amps. Way to big. Most
>ballast resistors are around 1 ohm and have a very high wattage. When  you
>run the ballast resistor in series with the injectors you should get a
>current load of around 7 amps which the computer can handle better. The
>things to do from here are. First check the ohmage of your ballast
>resistor then check to see how you have  got you injectors wired up. Your
>motor might start up with out the ballast resistor but it will tend to
>overheat the switching resistor's quickly and probably blow them.

Paul, thanks for the reply:

The resistors are wired up as as for a 280ZX.  That is, there is one
resistor in series with each injector (ie there are six).  The resistors
are installed in the power supply lines from the battery.

Each resistor measures about 6.5 Ohm  (Nissan says they should be 'about 6
Ohm').  As to Wattage, I can't say, but I would guess at around 15-20W.
Certainly the resistors I'm using are from a 280ZX and their power
dissipation should be adequate.

The ECU has two drivers with each handling three injectors in this case.

Taking this a step further, it may be that the resistors I am using are too
'big' - but how do I determine the correct value ??

I suppose one way around this problem would be to use another type of
injector which doesn't reuired the ballast.   But this would be added
expense (resistors are cheaper !!) and I have already determined that the
flow rate of the existing injectors should be adequate for the job.

BTW, the ECU I am using can supposedly handle up to 16 injectors (2 x 8),
so it should have an adequate current carrying capacity when only six are
used.

Cheers

Stephen Lamb
Dept. of Defence DSTO, AMRL
506 Lorimer Street
Fishermans Bend  VIC  3207 Australia
Tel: +61 3 9626 7525
Fax: +61 3 9626 7089

IZCC #180