Nissan Injectors....what gives ??

[Paul Rosser]

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.


Ps. The calcs above have been done for a 4 cylinder and I think the L28 is a six. If it is a six then the figures are worse. Please correct me.






 At 12:09 PM 2/26/97 +1100, you wrote:

>I've just spent the last few days doing a complete wire trace (several

>times !!) for the newly installed aftermarket injection system on my

>Datsun.  The reason ??.......even though the computer says it is getting an

>RPM signal (via a crank trigger indicating TDC) there was nary a peep out

>of the injectors.   I thought maybe the injector drivers had died.

>

>Now, almost by accident, I've found the likely cause of the problem.  I'd

>been advised to use 'ballast' resistors in series with these injectors as

>they are from an early 80's Nissan L28 engine and that's what Nissan did in

>those days.  I was told  the injectors wouldn't work properly without them.

>In a last desperate act to get the engine running, I  bypassed the

>resistors to power the injectors direct - lo and behold,  the engine starts

>and runs beautifully !!

>

>Can anyone shed any light on this ??.  The injectors show a resistance of

>2.5 Ohm in each case, which I'm told means that they need to run with the

>ballast resistors, but are there exceptions to this rule ?? (it seems that

>I have one !!).   Am I risking damage to my computer, injectors or anything

>else by doing this ?? (ie running without the resistors).  BTW, the

>resistors are off an engine of the same period and checkout OK.

>

>Any help greatly appreciated.

>

>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

>

>

>

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Paul Rosser

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New Zealand

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