Re: PicoScope NVH Useful or Not?

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Steve Smith
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Re: PicoScope NVH Useful or Not?

Post by Steve Smith »

Hi all, found your community on the search. I have been doing an internship at a Mercedes-Benz dealership and have been tasked with figuring out how to use the PicoScope NVH kit as well as where it can be applied. However, the more I use it, the less useful the scope seems to be.

At first glance, the kit seems to provide very good information to the technicians of problems related to the engine, propshaft, and tires. I also understand what the various orders mean. However, in real world testing, the scope seems less useful than I had imagined. Firstly, I am under the impression that the scope is limited in its usage to diagnosing problems relating to the engine, propshaft, and tires only (correct me if I am wrong). We recently simulated a previous customer issue in which the AC unit underneath the drivers feet would create a thumping, like a heartbeat, when the temperature was changed rapidly. However, this was not picked up by the accelerometer at all. Secondly, road testing only seems very reliable if you have access to a smooth roads where a large amount of bumps do not exist. Suspension related problems, or other problems alike, that only appear when the car goes over a bump are nearly impossible to detect using the scope as every vibration value shoots up when the car goes over a bump.

Almost the entirety of our technicians are against using this device in the first place and after using the scope, I am starting to see why. I know that the scope in useful in providing objective results instead of guesswork, but to the technician's credit, their experience and intuition seem to be much more applicable than what the PicoScope can provide. I cannot deny that the data that the PicoScope can provide is extremely useful, both to the technicians and the customers, but the instances in which the scope can be accurately used seem few and far between. The technicians have no problems in diagnosing 9/10 problems with the incoming vehicles and of that remaining 10%, the scope cannot be used in all of those cases either.



If anyone has any advice on using this NVH kit or would like to share their experience in using this kit, please share it in the comments, I would greatly appreciate your insight!


Hello and thank you for your open and honest feedback

It does seem odd that you have been tasked with “Figuring out how to use the PicoScope NVH kit” without any training and starting with NVH is starting at Step 5 of a 5-step process.

With that said, we are here to support all the way and I would like to start with the system you are using.

Could you confirm you are using Xentry Scope and NVH for Xentry?
I ask this because Daimler may have removed the facility to view both the Frequency Domain and the 3D Frequency view? (See below highlighted in red)
Image 1
Image 1
If this is the case, trying to detect unknown frequencies (such as the AC unit underneath the driver’s seat) is going to be challenging as it would be hidden from view given it does not sit with E, P or T vibration orders.

This also goes for detecting suspension anomalies related to the road surface and texture etc. as they too do not fall into “known categories.”

Amending the FFT settings topic17901-10.html#p82781">here> will also help but let’s come to that if applicable in your feedback and application

Could you send over your saved file re the above concern and we can check if this is the case?

Could you confirm you are based in the UK? I ask this because we are scheduled to train a number of Daimler trainers later this year and perhaps you could join the team?

I must say I am shocked to hear “Almost the entirety of our technicians are against using this device in the first place and after using the scope, I am starting to see why” but reading this comment back with hind sight, as a technician myself, if I had been handed a scope and asked to diagnose a vibration without any support or training I can see why this is the perceived consensus!

Using a Scope/NVH solution for the first time (in anger) does not make for a lasting positive experience.

Could I just clarify when you refer to “Scope” you are referring to Xentry Scope used in an NVH application or do you have concerns with Xentry Scope used as an Oscilloscope too?

If so, could you share your concerns with Xentry Scope as an Oscilloscope as we must tackle these collectively too

I agree whole heartedly with your comments surrounding the “experience and intuition” of the technician when it comes to diagnosis. The best diagnosis tools at our disposal are our senses backed by experience, (NVH is no exception) but how do we tackle those concerns raised by customers alleging “my car is too noisy or too harsh?”

Neither the customer or the technician is wrong as both opinions are subjective, however, to qualify a noise complaint from one vehicle to another we can use our NVH solution to capture objective & comparable data so avoiding attempts to repair characteristics.

I agree that the remaining 10% of vehicles may or may not need a scope as there is the right tool for the right job at the right time during the right process.

With that said if this leaves the team with 5% of vehicles that benefit from the application of our Scope (be that as a vibration solution or an oscilloscope application) we prevent the inherent costs of misdiagnosing these vehicles that in the worst case scenario result in a “Buy Back” and an unhappy customer who shares his unfortunate experiences with 10 other friends/colleagues.

Not only can we avoid the direct costs of the above, we avoid the indirect cost of losing future customers

It’s all food for thought and Pico would rather focus on supporting you and your team with the use of Xentry Scope/PicoScope and NVH

A good starting point for NVH application is our 7 part video series
https://www.youtube.com/watch?v=CLVVFoX1nIE">here> which covers you from “Out of the box” right through to knock detection and real life case studies.

Please let we know your thoughts and thank you once again for your honest feedback and first impressions of PicoScope

Take care……Steve

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TwoWaves
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Re: PicoScope NVH Useful or Not?

Post by Technician »

ironmathyu5

Don't be put off that easy with NVH and the scope. We learn at our own speeds and the software produced by Pico for their scope and NVH is second to none, what I mean there is it is first class. There is much data available for NVH and I'd of thought your company would have their own NVH data for your vehicles!

The Pico staff on here are excellent and will provide you much help and advice along your journey with NVH, so don't give up too easily.

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Unaly
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Re: PicoScope NVH Useful or Not?

Post by Unaly »

Thanks for this information, I hadn't other links on my post.

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