falha de combustao renouit clio 3

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antonio
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falha de combustao renouit clio 3

Post by antonio »

Renault_Clio_2008_Petrol_20220512-0001.psdata
(19.26 MiB) Downloaded 12 times
onde esta o problema ou a falha de combustao

Steve Smith
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Re: falha de combustao renouit clio 3

Post by Steve Smith »

Hello and thank you for the post

Before we continue Antonio, could you confirm the capture provided looks at exhaust tailpipe pulsations and referenced to cylinder 1?

I ask because there are no Channel labels and your pressure transducer appears set to Range 2 +- 1.4 bar.

If this is exhaust gas pulsations then could you take a look here viewtopic.php?p=103106#p103106

I would be happy to follow up on your capture “Renault_Clio_2008_Petrol_20220512-0001” as soon as you can confirm the signals on channels A and B

Take care…….Steve

antonio
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Joined: Wed Apr 14, 2021 11:47 pm

Re: falha de combustao renouit clio 3

Post by antonio »

ola ocanal A refere a onda tva [captada transdutor de pressao na admissao] e o canal B e a ignicao do cilindro n 1 , sera que existe algum problema nas valvulas .

Steve Smith
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Re: falha de combustao renouit clio 3

Post by Steve Smith »

Hello and thank you for the feedback

I have used the ignition event of cylinder 1 + approx. 10° as our TDC reference point (0 .. 720°)

See below: I have assumed a firing order of 1342
Image 1
Image 1
Uniformity and repetition are the ultimate goal when looking for anomalies in such waveforms and there are a couple of items highlighted above that we need to investigate

Above I have used the Pressure Waveform Overlay from Microsoft to help with identification of events in neighboring cylinders

I think we can agree that the intake “pull” for each cylinder occurs at the same point for all cylinders suggesting that the “full” closure of the exhaust valve and “full” opening of the inlet valve appear “on time” (approx. 30° after TDC on the respective exhaust stroke)

There appears to be a lot of turbulence/disturbance during the intake pull for cylinder 1 which I have highlighted with a large blue rectangle (again, compare this intake pull with neighboring cylinders)
This intake pull appears “stepped” in nature suggesting a change in cylinder volume (e.g. leak) or piston speed

Note how the commencement of the intake pulls for cylinder 1 and 4 are lower than cylinders 2 and 3 (highlighted with small blue rectangles)

Note also how the commencement of Cylinder 4 intake pull appears to be missing the defined double peak we see on the remaining cylinders suggesting a differing intake pressure during valve overlap

Could I ask what are the customer symptoms and how do these results compare with additional tests? (i.e., exhaust gas pulsations, 4-Gas analysis, crankcase pressure and DTC’s)

Please remember, this test is just one piece of the diagnostic puzzle and you have highlighted areas of concern

I would like to repeat this test when cranking from cold and again cranking from hot as valve clearances come into play here (especially with the missing double peak of cylinder 4 intake pull)

Using the cranking only test will also remove variables such as EGR if applicable to this vehicle?

If the vehicle uses LPG I would most certainly take a close look at exhaust valve clearances

I hope this helps, take care……Steve

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