Weird pattern observed in fuel injector current waveform

Anyone have any idea why by injector current waveform would have all of these waves in it?  This is a 2014 kia forte lx with a 1.8L engine.  This is a MPI system.  The capture is on injector 1.  Voltage is back probed at the injector on the control wire.  The current was taken with a pico low amp clamp set to 20A.  This was taken with a pico scope 4425A.  Some of the research I have found on the internet suggests that this could be an issue either with the injectors or with the injector circuit.  The uniformity of the pattern is what is throwing me off.  Anyone ever seen a waveform like this?  If this is not normal what could it indicate?  Thanks for any help anyone can offer getting this figured out. 

This looks like an electric motor current waveform. Where is your amp clamp located. Is it located at the fuse with a "fuse buddy"? Or, is it at the injector connector? Power wire or Control wire? 

Is the probe zeroed, properly? It looks like the ripple has a base-line of -216 mA.
Is the ripple there only with the engine running? Or, is it there during Key-on, as well?
To rule out a bad injector, you could disconnect the injector and use a noid light, or even a test-light in place of the injector. 

Thaks for the reply. Yes the amplitude is approx 216 mA and about 5Hz. I am using a pico low amp clamp 20/60 with it set on the 20 amp setting. It is a traditional BNC connector on a Pico 4425A scope. I have not yet sprung for the BNC+ low amp clamp. I did zero the clamp after connecting it but before putting it around the wire. I tried it on the control wire first and when I got the strange pattern I tried it on the power wire. Both wire yielded the same result. I have not tried to get a reading with KOEO but will definitely do that next. Also I was wondering if because I was trying to measure the primary voltage at the same injector at the same time I might have induced this undesirable interference into my attempt to measure the current ramp of the injector. I back probed the injector on the control wire and the amp clamp was right next to it. They were touching but the wire was not through the clamp jaws. I will also definitely give my test light an opportunity to put some work in and see if that points me to the correct conclusion. Thanks much for giving me some direction.

 

So I'm not sure what to make of this.  This is my Pico Low Amp Clamp TA018 connected to my PicoScope 4225A.  This isn't on any input its just with the probe connected and zeroed.  Whey would this pattern be there?  Could this be a faulty probe or am I screwing up a setting somewhere?

That ripple is not normal. Do you have good batteries in the amp clamp? Does the trace go flat if you disconnect the amp probe from the scope? Do any other test leads produce this ripple? 

I think you may have a bad amp clamp.   

Brand new 9V duracell battery in the amp clamp. The ripple goes away as soon as I unplug the low amp clamp from the scope. I even tried unplugging the laptop and running off of just the battery to see if there may have been some EM interference from the laptop power supply. The last thing I tried was opening and closing the clamp jaws several times and re-zeroing the clamp several times as well. Nothing seems to eliminate the ripple. I will be reaching out to Pico to see if they have any suggestions on how to resolve or if they can repair or replace the clamp. Thank you for your help.

I don't have a Pico, but if I use my Verus plugged in with the battery charging there is similar interference. I see that you tried it with your laptop power supply unplugged however, so that seems to rule out that.
Let us know what you find

Sent a data file off to pico tech to take a look at. I will keep you all posted when I get a response. They asked me to check amperage on a test light connected between battery positive and negative with the engine off to hopefully eliminate any stray emf interference. Ripple was still present in that signal.

Thanks for the update. I'm sure that they will fix it for you. My experiences with Pico have been very good. 

So after a few back and forth emails with Picotech they informed me that this noise is normal on the lower end clamp. I have in the meantime purchased a more premium clamp from Pico, the TA473 and that one works perfectly. I expressed my concern to Pico that this clamp is largely unusable for evaluating many waveforms as the noise makes subtle changes in a waveform indistinguishable within the waveform. A pintle hump in a fuel injector is just one example. I don't know if they will do anything to rectify the issue for me as the clamp was purchased back in April of this year (2025) and is past the 14 day return window. I am happy with my other Pico purchases so I will most likely continue to be a customer and use their products but this was a bad experience for me. I would recommend to anyone thinking of purchasing a low amp clamp from Pico to pass on the TA018. I can highly recommend the TA473 which is one version of the BNC+ clamp (goes for $340). I don't have any experience with the TA496 which is the compact version that goes for $277. Maybe that one would be good but after spending $133 on a clamp I really can't use I figured spending $63 more on the TA473 might keep me from regretting another purchase. In addition the TA496 seems to be on backorder so getting ahold of one is more difficult. Overall I'm still a Pico fan and who knows maybe they will do something to make me feel less bad about my purchase of the TA018.

Top notch customer service. Randy from Picotech has already responded to me and let me know that they will refund me the purchase price of the TA018 clamp. Picotech (Randy specifically) was very helpful through this entire process. Being able to send waveform files directly to Pico in a email format made it so much easier than trying to explain what my issue was. Pico has a satisfied customer for life after the way they quickly expedited a resolution for me.

Thanks for the update.