Injector Testing With Secondary Probe
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While playing around with it, I started to figure that it should be able to detect more than just coil firing. So how cool would it be to walk over to a car with a misfire and touch the coil to verify spark, and then use the same tool to touch the injector and verify operation?
At a 2v scale, 20ms time base I seem to get the cleanest captures. Now to compare to the methods we already have to try and dissect the waveform.
I'm trying to determine if mechanical movement can be inferred from the pattern. I think so, but I'm not there yet.
Let me know what you think.
Is it a viable test?
Am I just being stupid?
"Ground cannot be checked with a 10mm socket"
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Sorry the forum uploads my pictures sideways and upside-down
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"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."
I have learned more by being wrong, than I have by being right.
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The flexible handle for the probe is inspired, sir. I can see that being easy to get in under Escape intakes and such.
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2006 Cadillac CTS 4.6l
It looks like when the downward slope of the blue trace begins to climb is when the pintle hump is visible in the current ramp.
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- FrugalPrepper
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It's seriously not fancy, so don't be too disappointed.
I deftly extracted, well, more truthfully brutalized an old Civic distributer to get the pick up out of it.
That's the little tid bit in the middle.
It's much larger than that to start. After I harvested it I ground much plastic off it (per Tyler's instruction) to get it down to that little giblet.
For the handle i used the flexible neck from my Astro rechargable light, which was also brutalized in an unrelated event.
I fed an old set of meter leads through the handle and connected them to the leads of the pick up. It was a total shot in the dark as far as determining polarity. I figured if it sucked it could always return to the trash from whence it came.
I wrapped the whole deal in mastic tape which gives it a nice rubberized-ish handle and a not-so-piece-of-crap look.
One lead goes to chassis ground, the other goes to the scope.
Then it's just a matter of fiddling with the scope to get the best pattern.
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- Andy.MacFadyen
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- Andy.MacFadyen
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FrugalPrepper wrote: I am wanting to test with a stuck injector as well. I am trying to get these wave forms down. I was considering a trip to the salvage yard for an injector and then a syringe with some Harbor Freight Epoxy. I think I will be picking up a Honda distributor pickup as well now!
On plastic injectors a tool clip round the body of the injector works as capictive probe, found that out when we were exploring using knock sensors as injector probes --- there is a whole long thread on that. way back in the early days of the forum.
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Andy.MacFadyen wrote: On plastic injectors a tool clip round the body of the injector works as capictive probe, found that out when we were exploring using knock sensors as injector probes --- there is a whole long thread on that. way back in the early days of the forum.
You're talking about this one, right?
www.scannerdanner.com/forum/diagnostic-t...-a-knock-sensor.html
You've got some testing gold in there.
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That one?
Yes, that's a home made secondary ignition probe touching a fuel injector in yellow with the control voltage displayed in green.
Thank you for your interest
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- Jonathan Haffer
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Jonathan Haffer
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al514 wrote: Does the entire assembly need to be a certain resistance? Or just a coil of wire,and do you use any attenuators ?
I never gave the resistance a thought to tell you the truth.
As far as an attenuator, there's no danger of going over voltage since we're not actually measuring the KV the coil putting out. Instead we're measuring a much smaller voltage that's being produced by the distributer pick up interacting with the magnetic field created by the ignition coil firing.
Kind of like an amp clamp doesn't actually measure amps, but puts out a low voltage proportionate to the current flow in the circuit.
Plus the Snap On Verus scope will handle most of the high voltage produced from things like ignition coil primary voltage spikes without the use of an attenuator, so I don't even own one.
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That could be bad news.
That's why It's important to clamp one lead of the tool to block ground or chassis ground to minimize that danger.
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