How do i build a diesel injection pulse meter or adaptor ?

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Discussion Overview

The discussion revolves around the construction of a diesel injection pulse meter or adaptor, specifically focusing on sensing the injection pulse in the injector pipe and converting it to an electrical pulse for use with a strobe light, similar to those used in petrol engines. The conversation includes both mechanical and electronic injection systems.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant seeks assistance in building a device to sense diesel injection pulses and convert them for strobe light use.
  • Another participant suggests creating a 100 turn loop of magnet wire around the injector solenoid and using a 2N3055 transistor to trigger the strobe light.
  • A different participant questions whether it would be easier to sense the signal controlling the injector solenoid directly.
  • One participant inquires about the type of injection system (mechanical or electronic) to provide more tailored advice.
  • Another participant notes that the project involves sensing mechanical fuel injection and references a commercial adaptor from Snap-On tools.
  • A participant mentions the need to find the pulse from the high-pressure injection line over the #1 cylinder.
  • There is a reiteration of the interest in understanding how the Snap-On adaptor works, particularly in relation to a pressure sensor.

Areas of Agreement / Disagreement

Participants express various approaches to sensing diesel injection pulses, but there is no consensus on the best method or the specifics of the implementation. Multiple competing views remain regarding the type of injection system and the most effective sensing technique.

Contextual Notes

Participants mention challenges related to monitoring mechanical injection systems, including the difficulty of detecting pressure changes and the potential need for vibration sensors. The discussion reflects a range of technical considerations and assumptions that may not be fully resolved.

Who May Find This Useful

Individuals interested in automotive engineering, specifically those working with diesel engines and fuel injection systems, may find this discussion relevant.

karldb
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Can anyone help me attempt such a project?

I basically need to be able to sense the injection pulse in the injector pipe (1/4 inch / 6mm dia.) and convert it to an electrical pulse so that a normal ignition timing light (strobe light) can read the input as it would on a petrol/spark ignition engine.

thanx for your time.
 
Last edited:
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Make a 100 turn loop of #26 magnet wire that is large enough in diameter to put around the injector solenoid (loose loop). Wrap tape around to hold the loops together.

Drive the base-emitter on a 2N3055 transistor with the loop outputs. Connect your strobe trigger connection across the collector-emitter on the transistor.

You might want to add a 1k, 1/4 watt potentiometer in series on the transistor base and start with it at 1k, adjusting down until it's just enough to trigger the transistor.

The 2N3055 is pretty cheap and it has pretty high gain. This means it will use very little induction current from the injector to trigger it.

Enjoy!
 
Can't you just sense the signal controlling the injector solenoid in the first place?

- Warren
 
Karl - is this mechanical or electronic injection? For electrical, see above.

For mechanical, that should be in the service manual for the engine and calibrated to the pump drive. Well, with my limited exposure anyways... Otherwise you'd need to monitor the pressure (tough) or attach a vibration sensor to detect the opening when the pressure has exceeded the required pressure and then the closing when the pressure has fallen, not so easy as well. For a given RPM you could design a circuit that could compensate for only being able to monitor the closing, but eliminating the vibration from combustion might be very hard. Just thinking out loud...and a seasoned diesel tech would probably have a lot more suggestions.

Cliff
 
This is to sense mechanical fuel injection.'Snap-On' tools has this type of adaptor on the market,i was just trying to figure how it works.
 
The sensor is around over the #1 cylinder high pressure injection line. Does anyone know how to find this pulse?
 
karldb said:
This is to sense mechanical fuel injection.'Snap-On' tools has this type of adaptor on the market,i was just trying to figure how it works.
I did a search on Snap-On and one of the testers was required to be used with their pressure sensor. What unit are you looking at?
 

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