×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Injector dry firing?

Injector dry firing?

Injector dry firing?

(OP)
During a test session inside the trailer, our injectors lock up (at least make a drastic change in sound) at any opening  event requiring more than 15.7 m-sec PW. ~85% duty cycle. The test is very short taking less than 30 seconds to complete, but I wonder if that matters.

Note there was no fuel being supplied to the injectors and I am curious if this totally invalidated the test. I understand that the fuel pressure will tend to help close the injectors, that seems straight forward, but what is the effect?

Thanks
Craig



RE: Injector dry firing?

I know I wouldn't put my injectors through much testing without fuel going through them at high duty cycles, but it shouldn't kill them, unless you hold them static (100% duty cycle).
What kind of injector are they: Peak and Hold (low impedance) or Saturation (high impedance)? And are you sure they are the right type for the injector drivers in the ECU?

How are you measuring duty cycle? With an Oscilloscope (right way) or by looking at the fuel injection system's output of pulsewidth?
Why are you dry testing them anyway?
Hopefully you can put an oscilloscope on the driver side and see if they are going static, even if the fuel injection software says they aren't.
I would check that and see what is actually going on.

RE: Injector dry firing?

I think your best bet would be to run some fuel through them, even at low pressure, when you test them since the fuel lubricates and cools the injectors. Running them dry could heat them up and change the resistance of the coils, making your test results very inaccurate. Theres also the possiblity that you could burn out the injectors dry firing them, but thats unlikely in that short of a test.

-Jon

RE: Injector dry firing?

(OP)
Thanks for the replies guys,

The folks at BDS said I shouldn't have a problem with the dry fire mode provided the test duration was short.

Turns out we were not really at 85% Duty Cycle. Opening time and closing time was really eating up the cycle and we were on the edge of static.

Ouch!

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources