[v12-engine] V12 Bosch fuel injectors recommended hook-up polarity

V12-Engine
1

Hello, could someone confirm me whether Bosch/Lucas advices for
their fuel injectors a certain hook-up polarity?
As I have found out that the manufacturer for those Tecalemit fuel
valves on a twin tank setup (Series III) recommend a certain
connection polarity; I was wondering whether this also counts for
the fuel injectors? I’m just about replacing the injectors cracked
harness, and found only 4 with an inverted hook-up polarity. So
there could be a defenite concensus? As I’m very aware of that for
the injectors coils, normally the polarity doesn’t matter; I anyhow
measured for each 12 injectors individually a constant difference
for one polarity to the other. Let’s say + & - gave 5.3 peak Amps,
where - & + started at 4.8 Amps peak. Both quickly decaying to a
steady 3.3 Amps, giving a firm click. I did repeated these
measurements, with a professional Fluke Scope/multimeter. All was
performed with a well stabilized 13.6Vdc and a 1ohm resistor in
series to limit the injector coil current. The engine not running,
but with the pump running to maintain steady fuel rail pressure.

Nevertheless, I remember once somebody remarked there should be a
small + sign on the injector connector body, I can’t notice any.

Could this initial peak current difference signify a certain
injector opening time difference? Dunno, but I just wanna be
consequent in wiring them all correct and even the best way
possible. Just a thought, any ideas?

Harry '87 HE Sovereign Belgium–
Zarri-X
Brabant, Belgium
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2

Harry,

Hello, could someone confirm me whether Bosch/Lucas advices for
their fuel injectors a certain hook-up polarity?

There is no polarity.

However, I have found a small advantage in making
them all the same. This helps if you are putting some kind of pulse
measuring device on the injectors, e.g., an oscilloscope. If they are
all the same way you can get the probe connected the right
way on the first try.

As I’m very aware of that for
the injectors coils, normally the polarity doesn’t matter; I anyhow
measured for each 12 injectors individually a constant difference
for one polarity to the other. Let’s say + & - gave 5.3 peak Amps,
where - & + started at 4.8 Amps peak. Both quickly decaying to a
steady 3.3 Amps, giving a firm click. I did repeated these
measurements, with a professional Fluke Scope/multimeter. All was
performed with a well stabilized 13.6Vdc and a 1ohm resistor in
series to limit the injector coil current. The engine not
running, but with the pump running to maintain steady fuel
rail pressure.

That’s interesting. It would take a better electrical person
than me to tell you why.

Nevertheless, I remember once somebody remarked there should be a
small + sign on the injector connector body, I can’t notice any.

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3

In reply to a message from Zarri-X sent Wed 16 Nov 2005:

If the measurement had been carried out properly this question
would never have arisen.

The injectors used on the HE V12, like others of similar
construction, are not polarity conscious.

Because of the low resistance of 2.5 ohms these injectors can draw
enough current to cause the winding to heat up quite quickly and
this will cause the resistance to rise and so the current will fall
accordingly.

If the current is measured so that winding temperature has no
influence on the result it will be found that the current is the
same to within 0.001 amp in either direction in all circumstances.–
The original message included these comments:

measured for each 12 injectors individually a constant difference
for one polarity to the other. Let’s say + & - gave 5.3 peak Amps,
where - & + started at 4.8 Amps peak. Both quickly decaying to a
steady 3.3 Amps, giving a firm click. I did repeated these

–
Roger Bywater / AJ6 Engineering
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4

In reply to a message from Zarri-X sent Wed 16 Nov 2005:

Zarri-X,

As Ed Sowell indicated (which he educated me on), there is no
injector polarity. The electrical connector can be hooked either
way, to the injector.

However, plugging in the electrical connector such that the ‘‘C’’
or ‘‘U’’ shaped notch on the harness electrical connector is in
the ‘‘up’’ or ‘‘top’’ orientation position is the proper way to connect
the connector to the injector. Doing such facilitates electrical
diagnostics of the injector driver circuitry.

Off the vehicle ohm testing of the injectors (at varying temps of
65F to 85F) should give something around 2.8 ohms resistance. Your
readings seems high? Approaching twice the spec ??

I’m curious as to what your particular injector part number is?

Also, a bit unclear as to your mention of a 1.0 resistor? Why would
you do that?

SD Faircloth
www.jaguarfuelinjectorservic.com–
www.jaguarfuelinjectorservice.com
Jacksonville, Florida, United States
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5

In reply to a message from SD Faircloth sent Thu 17 Nov 2005:

Hello again Mr.Faircloth,
the 1.0 ohm resistors was added in series to avoid burning the
injectors coils, so my values you should take count for this
additional resistance. The injectors are the original Bosch 0-280-
150-161/2. They measure about 2.5 ohms
As Kirby and Roger already counter fighted my ideas about this peak
current difference, with reason.
(As for basic relays, the applied voltage polarity doesn’t matter)
I thus also mentioned with both polarities, the initial peak
current difference, decays very fast (–
The original message included these comments:

As Ed Sowell indicated (which he educated me on), there is no
injector polarity. The electrical connector can be hooked either
way, to the injector.
Off the vehicle ohm testing of the injectors (at varying temps of
65F to 85F) should give something around 2.8 ohms resistance. Your
readings seems high? Approaching twice the spec ??
I’m curious as to what your particular injector part number is?
Also, a bit unclear as to your mention of a 1.0 resistor? Why would
you do that?
SD Faircloth

–
Zarri-X
Brabant, Belgium
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6

In reply to a message from Zarri-X sent Fri 18 Nov 2005:

Hello again Mr.Faircloth,
the 1.0 ohm resistors was added in series to avoid burning the
injectors coils, so my values you should take count for this
additional resistance.
The injectors are the original Bosch 0-280-150-161/2. They measure
about 2.5 ohms
As Kirby and Roger already counter fighted my ideas about this peak
current difference, with reason. (As for basic relays, the applied
voltage polarity doesn’t matter)
I thus also mentioned with both polarities, the initial peak
current difference, decays very fast (–
The original message included these comments:

In reply to a message from SD Faircloth sent Thu 17 Nov 2005:

Also, a bit unclear as to your mention of a 1.0 resistor? Why would
you do that?
SD Faircloth

–
Zarri-X
Brabant, Belgium
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7

I continually point out that the original factory specs are to be found
on my web site: www.12claws.com
That should give anyone more than enough data to decipher a V-12 fuel
injector, the disclaimer being that if you’re fooling around with the
injectors on that scale, you should know enough to convert the units on
the spec to whatever you need and you should also be able to translate
such German complexities as “statisch” and “dynamisch” to their English
equivalents.

John Robison
EEX1 Development Engineer - Oxygen Sensors
e-mail: john.robison@us.bosch.com
Phone: (864) 260-8689
Fax: (864) 260-8118
Robert Bosch Corporation
4421 Hwy 81 North
Anderson, SC 29621

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8

In reply to a message from Zarri-X sent Fri 18 Nov 2005:

I’m still convinced that it’s maybe worth the consideration, where
one should imagine this difference in peak current could be the
straight result for a difference in initial peak torque of the
elector-magnetic lift force on the spindle inside the injector
body. Than this has defenitely an influence on the injector opening
time. It has to overwin a spring force and the fuel pressure.
Now, what I haven’t yet figured out is whether a higher initial
peak current, means a higher initial peak torque (read faster
injector turn-on time-i.e. opening time). Or on the contrary, does
this higher peak current, signify a somehow delayed lift, thus
slower turn-on time; maybe due to the vertical direction how the
coils windings start. Imagine from top-to-bottom wire wound, or
vice-versa.
Nevertheless, when speaking about such limited injector opening
times, in the order of milli-seconds,
I can quiet imagine that this is a rather important detail.
This would conclude my choice of polarity that I’d apply for.

Anyhow, when consulting several Engineering and Bosch notes,
I can’t find a straigth answer to this.–
The original message included these comments:

As Kirby and Roger already counter fighted my ideas about this peak
current difference, with reason. (As for basic relays, the applied
voltage polarity doesn’t matter)
Zarri-X
Brabant, Belgium

–
Zarri-X
Brabant, Belgium
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9

Zarri,

You can construct the response curve from the injector spec sheet and
they are different based on each OE’s requirements. Most of the (Bosch)
injectors are designed to use the same current, however. The response
changes due to the spring rate (some are variable) and the size of the
fuel orifice. It’s out of my general area, but I have seen the response
curve roughly constructed in a few minutes time. It’s not something
you’d see published because the spec sheets (Prufdaten Blatts) are not
generally available. No promises, but I’ll see if I can find an injector
contact in Charleston who can provide what you’re looking for.

Regards,
John Robison
EEX1 Development Engineer - Oxygen Sensors
e-mail: john.robison@us.bosch.com
Phone: (864) 260-8689
Fax: (864) 260-8118
Robert Bosch Corporation
4421 Hwy 81 North
Anderson, SC 29621

polarity

In reply to a message from Zarri-X sent Fri 18 Nov 2005:

I’m still convinced that it’s maybe worth the consideration, where
one should imagine this difference in peak current could be the
straight result for a difference in initial peak torque of the
elector-magnetic lift force on the spindle inside the injector
body. Than this has defenitely an influence on the injector opening
time. It has to overwin a spring force and the fuel pressure.
Now, what I haven’t yet figured out is whether a higher initial
peak current, means a higher initial peak torque (read faster
injector turn-on time-i.e. opening time). Or on the contrary, does
this higher peak current, signify a somehow delayed lift, thus
slower turn-on time; maybe due to the vertical direction how the
coils windings start. Imagine from top-to-bottom wire wound, or
vice-versa.
Nevertheless, when speaking about such limited injector opening
times, in the order of milli-seconds,
I can quiet imagine that this is a rather important detail.
This would conclude my choice of polarity that I’d apply for.

Anyhow, when consulting several Engineering and Bosch notes,
I can’t find a straigth answer to this.
Zarri-X

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Subject: Re: [v12-engine] V12 Bosch fuel injectors recommended hook-up

10

In reply to a message from Robison John (AP/EEX1-Ad) sent Mon 21 Nov 2005:

Well John, that would be nice,
I know it sounds strange to many, an injector coil is thought to be
uninfluenced by the applied polarity to. But as an electronics test-
and measurement engineer, I’m very well aware of how to do a
correct measurement. And the difference is there, on all my 12
injectors. That’s why I’m so convinced in a particular reason, and
why I’m looking for a concensus in wiring them up with a certain
polarity. Now what do you think of this idea? I still haven’t yet
figured out whether a higher initial peak current, means a higher
initial peak torque (read faster injector turn-on time-i.e.
opening time). Or on the contrary, does this higher peak current,
signify a somehow delayed lift, thus slower turn-on time; maybe due
to the vertical direction how the coils windings start?

Unfortunaly I’m not in the posibility of constructing myself a
complete test bench, with pressurised fuel, etc…
But I will try to measure for a difference in final fuel delivery
with one or another polarity. Nevertheless, this will take me a
while to construct an adjustable power puls generator,and …

Please could you give me your thoughts on this, before I would
attempt me to start creating such research facility? I know it
sounds crazy, but it’s just out of curiosity that I’m trying to
solve this phenomenom. Probably it won’t give any profitable gain;
or just maybe would it?

Best regards, Harry.–
The original message included these comments:

You can construct the response curve from the injector spec sheet and
they are different based on each OE’s requirements. Most of the (Bosch)
injectors are designed to use the same current, however. The response
changes due to the spring rate (some are variable) and the size of the
fuel orifice. It’s out of my general area, but I have seen the response
John Robison
Subject: Re: [v12-engine] V12 Bosch fuel injectors recommended hook-up
polarity

–
Zarri-X
Brabant, Belgium
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11

Hello!

When I replaced the Injector harness on my car with one I built myself,
except for the 8-pin connector, I checked the factory harness first and
found inconsistencies regarding which pins on the injector plugs were wired
to the Pink/Slate(Grey) wires, which are definitely “+” polarity as they are
connected to the ignition feed and are actually common with each other, as
well as the various Orange/Blue/Green/White/Slate(Grey) “-” ground wires
that have distinct paths to the EFI ECU.

I also performed a Google search and found a site that revealed a tiny “+”
sign on the outside edge of the Injector socket. If you have some Injector
sockets facing forwards towards the front of the car, walk around to the
passenger side (USA), grab a magnifying glass, and remove the injector plug,
with the Magnifier and maybe a flashlight you will see a tiny “+” molded
into the side of the socket.

I used this as the basis for my harness and have not had any problems.

kind regards to all,

-Don Buresh, 1991 XJ-S V12 Coupe, Classic
Orlando

Well John, that would be nice,
I know it sounds strange to many, an injector coil is thought to be
uninfluenced by the applied polarity to. But as an electronics test-
and measurement engineer, I’m very well aware of how to do a
correct measurement. And the difference is there, on all my 12
injectors. That’s why I’m so convinced in a particular reason, and
why I’m looking for a concensus in wiring them up with a certain
polarity. Now what do you think of this idea? I still haven’t yet
figured out whether a higher initial peak current, means a higher
initial peak torque (read faster injector turn-on time-i.e.
opening time). Or on the contrary, does this higher peak current,
signify a somehow delayed lift, thus slower turn-on time; maybe due
to the vertical direction how the coils windings start?

Unfortunaly I’m not in the posibility of constructing myself a
complete test bench, with pressurised fuel, etc…
But I will try to measure for a difference in final fuel delivery
with one or another polarity. Nevertheless, this will take me a
while to construct an adjustable power puls generator,and …

Please could you give me your thoughts on this, before I would
attempt me to start creating such research facility? I know it
sounds crazy, but it’s just out of curiosity that I’m trying to
solve this phenomenom. Probably it won’t give any profitable gain;
or just maybe would it?

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12

In reply to a message from Don Buresh sent Fri 25 Nov 2005:

Well Don that would be very interesting,thanx a lot for the reply!
You wouldn’t perhapse still have the URL for that site ?
Just for the record, could you send your injectors partnumber?
Just to be sure, since I have great eyes,and monitored my injectors
carefully, without any noticable ‘’+’'sign. Or is it really that
tiny, so a magnifying glass is necessary.
My Bosch injectors are labelled 0-280-150-161/2.
With the USA passenger side, do you refer to a right hand driven
car? It’s easier talking about the engines banks: where A is right,
and B the left side; as seen from inside the car, facing towards
front driving direction.

Anyway, again, Great Thanx for the info yet! Harry '87 HE–
The original message included these comments:

I also performed a Google search and found a site that revealed a tiny ‘’+’’
sign on the outside edge of the Injector socket. If you have some Injector
sockets facing forwards towards the front of the car, walk around to the
passenger side (USA), grab a magnifying glass, and remove the injector plug,
with the Magnifier and maybe a flashlight you will see a tiny ‘’+’’ molded
into the side of the socket.
-Don Buresh, 1991 XJ-S V12 Coupe, Classic

–
Zarri-X
Brabant, Belgium
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13

Hello Zarri-X,

As far as I know, the Injectors are what came with the car, I do not know
their part number. Yes the “+” sign is that tiny, so wipe the area clean and
use a flashlight and a Magnifying Glass. A USA-spec car is Left Hand drive.
No, I don’t have the site, you’ll have to do a Google search just like I
did.

-Don Buresh----- Original Message -----
From: “Zarri-X” jaggy-x@hotmail.com
To: v12-engine@jag-lovers.org
Sent: Friday, November 25, 2005 12:45 PM
Subject: Re: [v12-engine] V12 Bosch fuel injectors recommended hook-up
polarity

In reply to a message from Don Buresh sent Fri 25 Nov 2005:

Well Don that would be very interesting,thanx a lot for the reply!
You wouldn’t perhapse still have the URL for that site ?
Just for the record, could you send your injectors partnumber?
Just to be sure, since I have great eyes,and monitored my injectors
carefully, without any noticable ‘’+’'sign. Or is it really that
tiny, so a magnifying glass is necessary.
My Bosch injectors are labelled 0-280-150-161/2.
With the USA passenger side, do you refer to a right hand driven
car? It’s easier talking about the engines banks: where A is right,
and B the left side; as seen from inside the car, facing towards
front driving direction.

Anyway, again, Great Thanx for the info yet! Harry '87 HE

The original message included these comments:

I also performed a Google search and found a site that revealed a tiny
‘’+’’
sign on the outside edge of the Injector socket. If you have some
Injector
sockets facing forwards towards the front of the car, walk around to the
passenger side (USA), grab a magnifying glass, and remove the injector
plug,
with the Magnifier and maybe a flashlight you will see a tiny ‘’+’’
molded
into the side of the socket.
-Don Buresh, 1991 XJ-S V12 Coupe, Classic

–
Zarri-X
Brabant, Belgium
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services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !

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14

In reply to a message from Zarri-X sent Fri 25 Nov 2005:

Harry (Zarry? Jaggi?),

I have already told you these injectors are NOT polarity conscious
in any way. That is a fact and you will find no evidence otherwise
in any published information � of which I have a substantial
amount - or from any properly made observations. There is no +
indicator on any injectors I have ever seen (I have just wasted a
few minutes checking a few different examples) although there is
often a small moulded logo that might possibly be confused in that
way, but would it not be prominent rather than needing a magnifying
glass if it were an issue of any importance?

Whatever conclusion you may have arrived at to the contrary is due
only to flaws in your method of measurement. Is it not obvious that
applying a supply of 12 or 13 volts across a low resistance winding
will introduce a temperature variable that will cause
inconsistency? At that voltage the current will fall to less than
2.5 amps in under a minute.

Now please let the subject close.

I might also suggest that you could usefully spend some time in
study and equip yourself with a more thorough knowledge of the
subject. You might then find that you would not raise issues of
such irrelevance.

Bosch quote the injector opening and closing actions as taking from
1 to 1.5 milliseconds depending on the supply voltage, a parameter
for which ECUs apply a correction.–
The original message included these comments:

I know it sounds strange to many, an injector coil is thought to be
uninfluenced by the applied polarity to. But as an electronics test-
and measurement engineer, I’m very well aware of how to do a
correct measurement. And the difference is there, on all my 12
injectors. That’s why I’m so convinced in a particular reason, and
initial peak torque (read faster injector turn-on time-i.e.
opening time). Or on the contrary, does this higher peak current,

–
Roger Bywater / AJ6 Engineering
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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