Will an alalog mult meter "blip" fast enough to act as a node light?

[Zeke]

I need to test the FI wiring harness. All my injectors are Ohming out evenly and are clean. I might have a problem with a wire. I might. Just in case, can I use the analog meter to see if they are firing? How 'bout a timing light? Any way to trigger that?

[Zeke]

No info?

[Jeff Alton]

On my 951 I just used a small led and watched it while I cranked the motor with my remote starter.

I am not sure if a multimeter will blip fast enough, but you could try.

Cheers

[rick-l]

You're talking about using the amps scale and putting the meter in series and seeing if the needle deflects? It is definitely DC current and the needle should deflect somewhat.

I would be curious to see the results whatever.

[Zeke]

Amps, or DC voltage on the lowest setting? Just need a blip to verify continuity from the DME. I think digital meters are too slow to react. Mine is.

[zbph10]

Analog meter on DC volts should see the injector fire. You'll never see it with a digital.

Brian

[Zeke]

That's kinda what I figured. I'll give it a go. I wonder why digitals are "buffered" like that? No moving parts and LCDs are lightening fast, or am I thinking of LEDs? What's on a stopwatch?

[rattlsnak]

not so sure if youll see it. it happens in milliseconds. it may look steady instead of pulsing.

[TroyGT]

Milt... $15 bucks at Autozone will get you a set of noid lights that'll fit Bosche and all other major brands. They come in a nice red hard case too. I just did this during my last 'no start' fiasco.

-Troy

[ToddM]

Originally posted by rattlsnak
not so sure if youll see it. it happens in milliseconds. it may look steady instead of pulsing.

Exactly you will see some steady reading and not a pulse if it is too slow.

What you want is a cheap analog oscilloscope that has a trigger function.

[SolReaver]

No, You need a Bosch Noid to do it right.
They are cheap.

The continuity test on an injector pretty much tells you the windings are intact. not if the injector is any good.

Are you missing a cylinder?

[TroyGT]

Like I said... you can get a set of noid lights at Autozone... a specific Bosch one is included in the set. Cheap and easy.

-Troy

[MikeBogue]

I tried this test when I was working on an RX7 and was not able to determine if there was a signal due to the short duration of the impulse.
The reason that the digital meters will not work for tests like this is a low sampling rate. The oscilloscope is basically a multi-meter with very high sampling rate.

[Joe Bob]

Originally posted by SolReaver
No, You need a Bosch Noid to do it right.
They are cheap.

So is Milt....

[ToddM]

Yeah a light won't give you the time base

[djpateman]

The analog meter requires time for the needle to respond, and enough power in the signal.
The digital meter requires time to 'guess' the signal level and display it.
Both are only suitable for solid signals, not pulses. For rapid repetitive pulses an analog scope is good, but for slow pulses or intermittent events you need a digital storage scope and deep pockets.

[munsonbw]

As mentioned, if you want to see if the wire is good and DME is giving the signal, a LED will work fine. I don't know what a noid light consists of, so it may offer features that are worth the extra money. The LED tester consists of a red LED (if color matters) and a 270-390 Ohm resistor between the test point and the positive side of the LED (in series). I have used this on my MS install and you can trace signals through the circuit, which was very handy. Just use a stiffer wire and you can use the wire as leads.. strip 1/8" and tin the end.

[Zeke]

OK, thanks. I used to have an old WWII era oscilloscope and the only thing I knew to do with it was hook it up to a stereo and "watch" the music. Lots of fun with a big fat doob and a beer.
But that was 35 years ago. You can see the extent of my electronic skills.

Yes, I have a dead cylinder and am going through the process of elimination. I have about 10 injectors to use and have checked the windings on each with the Olm meter. There is one olming out a little low suggesting that the windings are starting to leak across. I'll use another matched and cleaned set. I just wanted to check my harness wiring to see if all is well. I just put some cleaned injectors in the thing 2 months ago and it started missing again. That last time, a set of cleaned up injectors made things as smooth as silk. No dirt in the lines.

[ToddM]

You can pick up any used analog scope now for nothing. Tektronix 465B is a great analog 2 channel scope that has BW up to 100MHz. It will do you fine for almost anything car related.

You can get a 20Mhz analog scope for $100 on ebay

[Zeke]

Does it come with any doobage?