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


Spark Ignited Engine Vibration Signal

Spark Ignited Engine Vibration Signal

Spark Ignited Engine Vibration Signal

Hello All,

I've got accelerometer data from a running engine and the signal is confusing me. I'm looking at time domain vibration data and I'm seeing some very high impulse spikes that seem to line up with firing frequency. I normally would expect this however these spikes are all positive, there is no negative g bounce back in the signal at all...it's possible I'm missing something obvious but I can think of a situation where an impulse signal from an accelerometer does not have an up and down portion to it...it spikes up to say 10G's, then comes back down to zero, then spikes up again to 10G's and comes back down to zero again...it never does a 10G's up and neg 10G's down and quick decay like I'd expect for an impulse signal. I've attached a picture of some of the time data.

I'm looking to see if anyone would have a physical explanation for how that signal could be created on a running engine. Is this normal? Am I just over thinking this? Any help would be useful, thank you.


RE: Spark Ignited Engine Vibration Signal

can you post a picture of the engine, and the location and orientation of the sensor(s) ?

I picture if the sensor is oriented somewhat tangentially, it will be responding to torque variations on a flexibly mounted engine.

The torque jumps pretty high right around when the plug fires.

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! Already a Member? Login


White Paper - Considerations for choosing a 3D printing technology
The adoption of 3D printing into major companies’ product development life cycles is a testament to the technology’s incredible benefits to consumers, designers, engineers and manufacturers. While traditional production methods have limitations in manufacturability, 3D printing provides unparalleled design freedom due to the additive method of building parts layer by layer. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close