[Diy_efi] Noid lights with more functionality?

Mike niche
Mon Sep 10 05:33:50 UTC 2007


Hi Ernest,

Yes there are ways to do it without the need to measure milli-ohms, things like the connector
surface resistance is enough to mislead injector resistances so that makes it hard even if
you have a tester/multimeter capable of high resolution etc.

Its nothing hard really, so I might as well let slip ;)

When the injector fires it effectively stores the drive current as a magnetic field, when the drive is
taken away the magnetic field has to go somewhere and this results in the classic "back EMF"
from the equation V=L.di/dt.

Where V= voltage produced, L=Inductance, di = change in current, dt = period of time

So the characteristic of the back emf changes if there is a shorted turn and it just takes one to
make this difference noticeable.

afaik, for the bosch injectors I use I guess they have a couple of hundred turns at least though I'm not sure of
the wire gauge, though from comparative observations on relays it appears like 0.5mm or so,

regards

mike



At 01:20 PM 9/10/07, you wrote:
>Mike,
>How would you get such a (presumably single LED) device to indicate whether an injector had a shorted turn? (Don't give away secrets, of course)   Is it possible to have a simple device read such a minor difference (or is it not minor?) and tell the user?  One turn only, shorted, or a number of them? (I have no idea how many turns an injector might have, or what guage wire.) The reason I ask is that I have a turbo EFI bike that is notorious for shorting turns of it's buried stator, so any clue that trouble is coming would help avoid the long AAA trip home.  Injectors on this bike test "between 1 & 3 ohms" per the manual, and mine measure 2ohms; can a shorted turn be picked out of that?
>Ernest
>
>
>
>
>----- Original Message ----- From: "Mike" <niche at iinet.net.au>
>To: <diy_efi at diy-efi.org>
>Sent: Sunday, September 09, 2007 8:46 PM
>Subject: Re: [Diy_efi] The so called "Noid" lights ?
>
>
>>Thanks for the comments guys,
>>
>>It probably would help if I explained the reason I raised the subject.
>>
>>These days modern electronics can be quite sophisticated, small and low cost,
>>
>>It should therefore be possible to design a "smart" noid light which does the very least such as:-
>>
>>a. Be "inline" with the drive to the injector to observe simultaneous operation.
>>b. Have it show polarity is the same on all injectors (assuming all 6 are wired correctly)
>> in situations where people build up looms and/or wishing to avoid polarisation if that is an issue.
>>c. Have it indicate whether the injector has a shorted turn.
>>
>>I dont need a Noid light for myself, though it might be a handy tool to leave in the box.
>>
>>Its raised my interest how people swear by them on the forum I listed yet, to me, they
>>seem very simple dumb devices and for the price I would have expected a little more.
>>
>>These days with LEDs using so little current (in comparison with the injector) it shouldnt
>>be necessary to worry about the injector resistance and just wire in a light in parallel in
>>some type of inline connector arrangement.
>>
>>Of course the electronics can be cheap and low cost even for a little sophistication
>>but it seems the packaging and presentation can still be a pain and I guess this is a stumbling
>>block...
>>
>>Thanks for the link to etoolcart but so far, that is the only one I have found even from the calaisturbo
>>site, there just dont seem to be any other people doing them on a commercial basis anywhere,
>>
>>Thanks
>>
>>Mike
>>
>>
>>
>>
>>
>>
>>At 10:36 AM 9/10/07, you wrote:
>>>Mike,
>>>
>>>I made one - I measured the resistance of the injector - then a small light
>>>- I added resistors to make the resistance similar.  I wired it in in place
>>>of the injector.  It seemed to work - it would light up about when I thought
>>>it it should.
>>>
>>>It seemed to work - but I never got the car running - so I'm not sure this
>>>is a good idea.
>>>
>>>Bobby
>>>
>>>On 9/9/07, Mike <niche at iinet.net.au> wrote:
>>>>
>>>>Over here in Oz, a "Noid" light seems to be just a simple LED
>>>>which goes in parallel with the injector, its a tool to verify the ECU
>>>>is driving its injector output and that the signal is getting as far
>>>>as the injector, ie All the way through the loom.
>>>>
>>>>You basically, unplug the injector connector and plug in the Noid
>>>>light intot he injector and the injector connector into the noid so
>>>>the noid is "inline" to the injector, when the injector is driven the
>>>>light is supposed to come on.
>>>>
>>>>My question is,
>>>>
>>>>Is this just a basic light or are there any inline type testers like this
>>>>that
>>>>are any more sophisticated ?
>>>>
>>>>I'm not complicating this at present with any Duty cycle issues, just
>>>>wishing
>>>>to find out if people are using anything more sophisticated than a simple
>>>>LED for their inline injector testing ?
>>>>
>>>>Regards
>>>>
>>>>Mike
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>At 02:35 AM 9/10/07, you wrote:
>>>>>Im not exactly sure what you are looking for, but this little tester is
>>>>very
>>>>>cool.  Its a dual led test light.  Magnetic pickups can light the leds >in
>>>>>this.  Its a pretty helpful little test light.
>>>>>http://www.etoolcart.com/index.asp?PageAction=VIEWPROD&ProdID=248
>>>>>
>>>>>You could try searching "injector pulse width meter" Not too much comes
>>>>up
>>>>>but i think this is more what your lookin for. Besides these, i cant
>>>>think
>>>>>of anything besides an oscilloscope.
>>>>>
>>>>>On 9/9/07, Mike <niche at iinet.net.au> wrote:
>>>>>>
>>>>>> Hi chaps,
>>>>>>
>>>>>> Nice to see some activity here re logging, a subject in itself, I >> have
>>>>>> idea for small cheapie
>>>>>> logger and finally pinned down an enclosure/connector combo, but its
>>>>not
>>>>>> USB, just serial
>>>>>> but would work for the most part with the cheapie usb to serial
>>>>>> adaptors...
>>>>>>
>>>>>> Anyway, i digress...
>>>>>>
>>>>>> I'm on http://www.calaisturbo.com.au  from time to time as "Niche" -
>>>>funny
>>>>>> that...!
>>>>>>
>>>>>> And some people use "Noid" lights to test they have drive to the
>>>>>> injectors, which is (as far
>>>>>> as I understand) just a LED light in a moulding which is pluggable
>>>>inline
>>>>>> with the loom
>>>>>> to the injector at the actual injector. So you can see it blink when
>>>>>> cranking etc...
>>>>>>
>>>>>> I'm interested to know if anyone has a "noid" like type tester or >> item
>>>>>> which does any more
>>>>>> than just light up an LED when the driver wants to turn on the >> injector
>>>>?
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Regards from
>>>>>>
>>>>>>
>>>>>> Mike
>>>>>> Perth, Western Australia
>>>>>> VK/VL Commodore Fuse Rail panel that wont warp, twist or melt,
>>>>>> guaranteed  !
>>>>>> Twin tyres for most sedans, trikes and motorcycle sidecars
>>>>>> http://niche.iinet.net.au
>>>>>> _______________________________________________
>>>>>> Diy_efi mailing list
>>>>>> Diy_efi at diy-efi.org
>>>>>> Subscribe: http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>>>>> Main WWW page:  http://www.diy-efi.org/diy_efi
>>>>>>
>>>>>_______________________________________________
>>>>>Diy_efi mailing list
>>>>>Diy_efi at diy-efi.org
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>>>>
>>>>
>>>>
>>>>Regards from
>>>>
>>>>
>>>>Mike
>>>>Perth, Western Australia
>>>>VK/VL Commodore Fuse Rail panel that wont warp, twist or melt,
>>>>guaranteed  !
>>>>Twin tyres for most sedans, trikes and motorcycle sidecars
>>>>http://niche.iinet.net.au
>>>>_______________________________________________
>>>>Diy_efi mailing list
>>>>Diy_efi at diy-efi.org
>>>>Subscribe: http://lists.diy-efi.org/mailman/listinfo/diy_efi
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>>>
>>>
>>>
>>>-- Toward freedom,
>>>
>>>Bobby Yates Emory
>>>_______________________________________________
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>>
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>
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Regards from


Mike
Perth, Western Australia
VK/VL Commodore Fuse Rail panel that wont warp, twist or melt, guaranteed  !
Twin tyres for most sedans, trikes and motorcycle sidecars
http://niche.iinet.net.au




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