The Autonerdz Community Forums - Wrangler From Hell (The Movie)

Tom Roberts

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Re: Wrangler From Hell (The Movie)
Reply #15 - Sep 6^th, 2009 at 3:41pm

Quote:

but can you explain how you done the running compression test with a transuducer?

First, the spark plug is removed and an open compression hose is put in its place. Then the pressure transducer is attached. This device converts the pressures into voltages that can be displayed on the scope. PicoScope also allows you to configure a custom probe so that these voltages are displayed in a pressure scale of your choice.

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Marks Auto Service Freshman Member Picogroup Offline Posts: 10 Gender:	Re: Wrangler From Hell (The Movie) Reply #16 - Jan 15^th, 2010 at 6:39am Wow, what a great video! , It really shows the in and out of the whole diagnostic process [and probably some dead ends too ] Awesome. Can the 3400 series catch this running comp. test for 8 minutes cheers Mark
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Re: Wrangler From Hell (The Movie)
Reply #17 - Jan 15^th, 2010 at 8:53am

Thank you, Mark. Glad you enjoyed it.

Yes the 3000 series can indeed capture the 8 minutes, just not at the same sample rate.

The 3000 scope would capture 500 seconds with a sample every 239 microseconds.

The 4000 can do it with a sample every 30 microseconds. That's about 8x faster.

The compression waveforms are lower frequency so you would have captured the compression peaks and seen the issue with a 3000 scope, just not quite as detailed. Wink

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Jray

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Re: Wrangler From Hell (The Movie)
Reply #18 - Mar 22^nd, 2010 at 5:07pm

Tom Roberts wrote on Sep 6^th, 2009 at 3:41pm:

Quote:

but can you explain how you done the running compression test with a transuducer?

First, the spark plug is removed and an open compression hose is put in its place. Then the pressure transducer is attached. This device converts the pressures into voltages that can be displayed on the scope. PicoScope also allows you to configure a custom probe so that these voltages are displayed in a pressure scale of your cho

ice.

Hello Tom great movie clip I enjoyed it very much-getting back to the compression wave form I did noticed when exhaust valve started to open the wave form was higher when the compression was low and when compression return to normal the wave form was lower

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joecar+ Guru Member Picogroup Offline Posts: 443 Southern California California USA	Re: Wrangler From Hell (The Movie) Reply #19 - Mar 23^rd, 2010 at 5:51pm Great movie... thanks... Question: would the exhaust valve show evidence of not seating...?
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Tom Roberts

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Re: Wrangler From Hell (The Movie)
Reply #20 - Mar 24^th, 2010 at 9:14am

Joe,

I don't think there was any damage or evidence of poor seating on the exhaust valve but we never took it apart to see. That was done back at the dealership.

I don't think that new head had been on there all that long though and the leakage only occurred for a short time during warm up. Not likely enough to develop visible evidence.

Jray,

We noticed only minor differences in the shape of the compression wave when compression dropped. The change in peak pressures was the key to the puzzle. Wink

All Picogroup members:

There is an extensive discussion thread on this in the Picogroup area too:

http://www.autonerdz.com/cgi/yabb2/YaBB.pl?num=1242149670/0

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