Comparing waveforms

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Burt_100
OneWave
OneWave
Posts: 39
Joined: Sat May 06, 2017 9:52 am

Comparing waveforms

Post by Burt_100 »

I have taken a waveform from a 1.4vti Peugeot engine and I have got one from the waveform library, Mine looks different and I am finding it difficult to compare, I tried to use the reference waveform data and overlay the waveforms but they start in different places and look like they are on different scales, I have tried to change this but I am still not matching up no matter how I try it can anyone help?
Attachments
Peugeot_207_2008_Petrol_20200321-0001-cranking.psdata
(519.4 KiB) Downloaded 356 times
20200323-0001.psdata
(501.66 KiB) Downloaded 362 times

ben.martins
Pico Staff Member
Pico Staff Member
Posts: 539
Joined: Tue May 16, 2017 1:02 pm

Re: Comparing waveforms

Post by ben.martins »

Hello Burt_100,

I think there are a few things we need to confirm being deciding anything. Firstly, the waveform you have from the library is that for a 1.4l engine? The only CAM CRANK waveforms I've seen that appear similar to the one you have is from a 1.6l version. Whilst the 1.6 (EP6) and 1.4 Peugeot engines were very similar there may be some differences that without a known good we can't be 100% sure of the result. It's worth remembering that this engine was used by a number of OEM's including BMW and Mini. I can see on the library that there are a number of 1.4 Mini's with CAM CRANK signals present although the testing conditions are different to yours.

You noted that the waveforms aren't lining up. This can be tricky to do when you are trying to compare cranking captures. There are many factors that will alter this between engines which could be mechanical issues causing resistance in cranking, starter motor concerns and battery voltages. If we take the two captures you have mentioned. I've used the file you have attached titled 20200323-0001 as the reference and then loaded the 1.6 207 CAM CRANK capture from the waveform library.
Peugeot 207 Captures Battery Voltage.png
You will notice the battery voltage in your file is much lower when not cranking measured at 10.7V and during cranking drops to a low voltage of 7.8V. Compared to the waveform library capture the battery voltage is 12.8V and at it's lowers 10.0V. Having a poor battery is of course going to mean the engine isn't cranked as quickly as an engine with a good battery. Because of this it's almost impossible to judge whether the timing is out as time will be different.
Peugeot 207 Captures CAM time comparison.png
The best thing I can suggest is if the engine will run, then take a capture of Cam and Crank whilst the engine is running. Remember to disconnect the oil control valves that will adjust the VVTi as this will naturally affect the timing.

I hope this helps and if you need any more assistance on reference waveforms then please let us know.

Kind regards

Ben

Sharpy
TwoWaves
TwoWaves
Posts: 55
Joined: Sun Dec 23, 2018 9:59 am

Re: Comparing waveforms

Post by Sharpy »

I have a 1.4vti that I have replaced the timing chain and it has no issues so I have took some captures from it using your settings so as good as a comparison you will get hopefully I also uploaded them to the library and done some running ones while I was there
CAMCRANK CRANKING VTI OIL DISCONNECTED.psdata
(217.47 KiB) Downloaded 369 times

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