[webcat]

Can you measure the output of the injector wires with a multimeter instead of using a noid light ?

i was thinking it would be just 12 volts applied to the injectors for a certain amount of (ON) time so i was thinking i could use a digital meter or mayby a analog meter would work and it would just flash 12 volts
Do you think it would work or do NOID lights have somthing special about them ?

 

['cudapaul]

No, it would work, but the meter will probably not read 12VDC since the current is being pulsed on and off.

You can use a 194 bulb with some test leads.

 

[webcat]

good deal i think i have a few 194 bulbs lay'in around .
Thanks alot Cudapal , thats some really good info.

 

[astro355]

No, it would work, but the meter will probably not read 12VDC since the current is being pulsed on and off.

You can use a 194 bulb with some test leads.

FYI, the signal to the injectors is not AC, it would be picked up as VDCs. Off would be 0.0Vs and on would be anything greater than 0.0Vs.

 

[gtkane]

Don't apply 12 volts to the injector directly...it will burn out.

 

[astro355]

Don't apply 12 volts to the injector directly...it will burn out.

Sorry, that's not what I meant. I was referring to using a DMM to measuring the voltage in the circuit.

 

[gtkane]

Gotcha...

I think I was reading it differently.....

 

[astro355]

Gotcha...

I think I was reading it differently.....

I did not specify! I should have been more detailed.

 

[webcat]

ok , i did a experiment and used this 555 timer to flash a led on and off to simulate fuel injector on time but instead of 12 volts flashing on it only goes up to 3.5 volts , but i was just trying to see how the digital multimeter would read volts that are fluctuating and it looks like you could probally use the meter to test your fuel injector wires
in the video i'm just comparing the led flashing on and off to the meter readings
note that the first part of the video the yellow meter was'nt working (unplugged or somthing) but the last part of the video the yellow meter was reading the on time , if anything it might of had a small lag that is reading the voltage slightly late , but it was working

[youtube][/youtube]

 

['cudapaul]

Apparently, my statement "but the meter will probably not read 12VDC since the current is being pulsed on and off" was misconstrued.

I did not imply that AC voltage was being sent to the injector.

If the voltage being fed to the injector is not CONTINOUS direct current, then the DMM will integrate the voltage reading to something less than 12 VDC. Since the injector pulse width is not 100%, and you don't know when the meter will read the voltage (DMM's update several times a second), the voltage that the meter will read (or integrate) will be LESS than 12VDC.

Saying that anything "on would be anything greater than 0.0Vs" is still not correct because the driver transistor could be shorted or leaky and you would have voltage present across the injector, or the injector could be open.

The only way to actually determine the pulse width and voltage is to look at it on an oscilloscope.

 

[webcat]

that would be pretty cool to see it on a scope.

 

[evil_motors]

if you have a harbor freight near you a noid light set is only like $15

 

[astro355]

Apparently, my statement "but the meter will probably not read 12VDC since the current is being pulsed on and off" was misconstrued.

I did not imply that AC voltage was being sent to the injector.

If the voltage being fed to the injector is not CONTINOUS direct current, then the DMM will integrate the voltage reading to something less than 12 VDC. Since the injector pulse width is not 100%, and you don't know when the meter will read the voltage (DMM's update several times a second), the voltage that the meter will read (or integrate) will be LESS than 12VDC.

Saying that anything "on would be anything greater than 0.0Vs" is still not correct because the driver transistor could be shorted or leaky and you would have voltage present across the injector, or the injector could be open.

The only way to actually determine the pulse width and voltage is to look at it on an oscilloscope.

Yes, but you would still get a reading. It would not be a continuous reading but the important thing is that it would change. If the reading did not change, you would know there is a problem.

Pulse width and voltage can be viewed using a scantool.