Maximum amperage of diesel injectors.

[mudnut]

G'day all. I am in the process of building an injector pulse tester.

I could buy one, but where is the fun in that? The circuit I am building is for non-direct injection petrol engines.

It uses a couple of 555 timers and a MOSFET which is rated at maybe 15 amps.

I know that the newer diesels use sequential and multi-stage injection patterns and so draw a very heavy current.

Since I am building this unit I may as well make it useful for any engine.

Could someone please let me know what the CRD injectors current rating is so I can select an appropriate MOSFET, fuses, clamps and cables?

[mudnut]

Bump. Anyone?

[the evil twin]

Bump. Anyone?

Have you googled the Bosch site?

[mudnut]

ATM I'm lucky to get to log on to the forum as I am on slowed data for another couple of days. What are the fuses rated at on the Injectors?

[the evil twin]

ATM I'm lucky to get to log on to the forum as I am on slowed data for another couple of days. What are the fuses rated at on the Injectors?

Wouldn't have a clue offhand but I doubt the pull anything like 15 amps, be only a couple of amps I reckon.
Gotta take Chewy the wonder dog for walkies before I loos a limb.
I'll see if i can find out anything and post up later on.

[the evil twin]

Well, couldn't be more wrong I spose...
Voltages and Currents are all over the shop depending on the site (lowest was 400 volts and 2 amp but I doubt that is correct for the CRD)
Bosch don't list the specs for the Nissan/Renault injectors, possibly because of commercial agreements but who knows

Best I could narrow it down to was Voltage 100V, current limited at 20 amps

[mudnut]

Thanks, ET. Much appreciated.

[Flex]

Most modern CRD injectors are piezo type i.e. they work more like a capacitor rather than a inductor (coil) They operate off a high voltage, usually around 300V. The ones in the ZD30 CRD are of this type. Also the injectors need to be "tuned" to the ECU as each injector parameters are slightly different (due to manufacture variation)

[mudnut]

Thanks. I'll have to have a goods look round before making any decisions. Cheers.

[Yendor]

Have you had a look in the workshop manual? It should at least give you the resistance of the injector.

[mudnut]

Yep. I've had a search. I haven't got the CRD manual downloaded as the GU manual caused all sorts of problems with my puter.

[the evil twin]

Have you had a look in the workshop manual? It should at least give you the resistance of the injector.

0.25 +/- 0.05 Ohms IE between 0.2 to 0.3 Ohms

[mudnut]

Thanks ET. So thats for The CRD?

12Volt /.2 ohms = 60 amps. That'll do as a reference point for now.

Factor in back EMF it will be a bit less.

Multiply it by 4 then you have a huge current drain that must be supplied by the alternator.

[the evil twin]

Thanks ET. So thats for The CRD?

12Volt /.2 ohms = 60 amps. That'll do as a reference point for now.

Factor in back EMF it will be a bit less.

Multiply it by 4 then you have a huge current drain that must be supplied by the alternator.

Good thinking 'cept the Injectors don't run on 12 volts, Cobber.
They run on somewhere between 100 to maybe 400 volts (Flex suggests 300 Volts peak which would make sense).

They are also not the only component in the circuit.
That means it would be like measuring the resistance of the headlamp switch at 0.2 Ohms and thinking the headlamp circuit pulls 60 amps.

From the very limited data on the Bosch website they will be limited to around 15 amps but whatever it is that would be max current at max duration.

[Yendor]

Looking at the wire size at the injectors my guess is around 20 amps.

I'm unable to see any working voltage on the injectors and the online photos I found don't help that much either.

You could try contacting some of the aftermarket chip mobs, maybe they could tell you.

[mudnut]

They are a hefty unit so I will source heavy duty gear. Do it once, do it right.

[Flex]

mudnut how did you go with this project?

[mudnut]

I have been collecting bits and pieces
for this project.

My computer is in a very poor state at

the moment, so I have been struggling

to do anything.

I did however find a circuit that had

some decent sized capacitors near

the output end of the circuit.

This indicates to me that it may be

used to produce a high voltage signal.

I have also found a circuit that can

accommodate a hefty mosfet for 12v.

The local electronics store is closing

down so I need to find a good online

supplier too.

[Flex]

Try these two:
RS Components: http://au.rs-online.com/
Element14: http://au.element14.com/

Both have overnight shipping. RS is free and element14 is free if your order is over $45

[mudnut]

Thanks. I'll have to shelve it for

the moment. But I definitely will go ahead

with it. There are plenty off the shelf units

on EBay, if you really need to have one.

I think I will get the plugs and leads from a

shop in Mt Gambier or Warnambool as it

will be easier to get the right type.

[mudnut]

I have been able to set up
an injector pulser circuit,
which gives a variable
output, using a cheap C2331
transistor which is way too
light duty. This circuit
only runs between 20 and
40 milliseconds as
I am only running a 12v
relay at the moment,
which freaks out when
dialled up to 50hz.

To get the more complicated
8 millisecond circuit with
1 sec pulse, 5 second pulse
and continuous output to
drive a high voltage diesel
injector is gunna be expensive.
I will have to invest in a bigger
bread board and a heavy
mosfet, some big capacitors,
some petrol and diesel
injectors and/or maybe
a transformer.

[mudnut]

I am a bit disappointed
with some switches I
got through Jaycar.
I have spent a bit of
time getting the Injector
pulser circuit working
on a bigger bread board.
I was getting weird
inconsistent results which
were driving me nuttier.
I traced it back to the
mini switches. I will have
to source some better ones.
I have also bought a high
amperage mosfet and
will set about designing
a circuit that suits the
CRD injectors.

[mudnut]

I have obtained some good
switches and redesigned
the timing circuit to
give me a continuous
pulse, a 1 second pulse
and a 5 second pulse.
The original circuit was
so sensitive, that attaching
the meters and oscilloscope
would affect the operation.
At this stage I only have
a relay as a substitute
for a 12 volt injector.

I still have to design
the high voltage output
to run the Piezo Injectors.

What I need now are
a CRD injector, a DI injector
and late and early model petrol injectors.
They have to be electrically
sound, but it doesn't matter
if the nozzle or inlet fitting
have been damaged.


So if you know of anyone
that has any, please PM me
thank you.

[mudnut]

Since I have not had a computer to research the circuitry involved with the DI and CRD drivers I have finished the 12v 18 amp pulser and the box to house it all in. I won't start on the pipework and gauges until I complete the electronics, so I have shelved the project at the moment. I also spiked the hand held oscilloscope so I need to invest in a more robust unit, so that has thrown a spanner in the works as well.