A quick tip when using a pressure transducer and a pulse sensor at the same time. Its a NO NO! Autonerdz link for your picoscope needs autonerdz.com/?wpam_id=2
You know the saying there’s mechanics and there’s technicians, I’ve often thought there’s a third category and this video displays it nicely. Great work!
Hi Mike, Many times I see Bernie (ATS) measure in-cylinder and intake pressures simultaneously without any apparent anomalies. What you point out is very interesting. I will keep that in mind... Thanks for sharing! I wish you and your family a Happy and Healthy New Year!
Yea I've seen his videos. I think his pressure sensors are all absolute pressure not pulse sensors ,the effect may be different. I only have 1 absolute pressures sensor, so I h have not experimented yet. Happy New Year.
Agree hundred percent on added volume reducing compression affecting crank shaft speed You can see the same effect with wps and when doing a relative compression test. Great info mike Happy new year🎉
Here's a fun comparison test: install an old-school compression tester in the plug hole (to have the hose add the extra volume to the cylinder.) Use a vacuum "T" to measure the intake manifold - one side to a pulse sensor, the other to your wps 500 set on absolute pressure. This test would show the pulse sensor having your anomaly (presumed by the change in engine speed,) but I'd expect the wps 500 to show each cylinder creating equal pressure pulls. This could prove how much engine speed variances affect the pulse sensor.
I guess if you go into it knowing what to expect its not to bad. I have never done RC and in cylinder at the same time. I just don't trust it. Thanks for adding to the conversation.
I believe the explanation is due to the EVO for the in-cylinder capture occurring at the same time as the overlap event for another cylinder. This additional volume reduces the effect of the intake pull on the manifold, leading to the “weak pull” you have displayed. My theory is this will not be as apparent in a 6- or 8-cyl configuration
Interesting theory i will have to rack my brain on it for a while. With my equipment 6 cylinders show an issue, I will have to revisit an 8 (its been a while) I personally just stopped all in cylinder and pulse sensor testing simultaneously, its to risky for me. Thanks for stopping by and commenting!
Interesting! This would be a fun test to repeat next time you're changing an exhaust manifold gasket. Then the exhaust volume won't be connected to other cylinders.
The piston is stopped at TDC, accelerates to max at 90*, decelerates to stopped at BDC. If the rate of change(speed) of the cylinder pressure, that the pulse sensor is responding to, affected the sensor’s output, then the output would be a curve instead of the linear straight line.
Hi Mike, thanks for the video, I greatly appreciate you sharing this information. I believe the First Look Sensor and the “pulse” sensor are both “delta pressure sensors”? Is there a reason you chose not to use the First Look in the intake manifold & vice versa?
I think the term pulse sensor and delta sensor are 1 in the same. I use my store bought first look sensor in the exhaust simply because its tougher than my home-made pulse sensor. It would do a fine job in the intake as well.
