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mwebb

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Re: firstlook
Reply #15 - May 5^th, 2007 at 9:58pm

i never had a communication problem with AceMisfireDetective on any version , one version was unhappy and would not record a full 20 screens , it did not like the sync pickup that came with the kit... i dont remember which version .

as a rookie , i have not graduated to 8cyl waveforms yet ...

the overlay is from Tom Clozza's article or discussion about vacuum waveforms .
      every one using the FLS should read that and Bernie Thompson's article in Motor Mag archive.

i have a copy and i know Wilf has a copy .
here is an overlay on top of a running compression waveform , marking out what happens when , you can make your own by running a running compression test then importing that save into ANNO wave ,

DO not use the FLS sensor for running compression , the one i did is with a FLUKE PV 350 ,
   which sux , dont buy it . useless as mudflaps on a sledghammer . terrible resolution.

   allow for ignition timing advance and overlay on spark parade to see what intake or exhaust valve is opening when .
   in ANNO wave you can stretch or shrink or whatever and the overlayed template image stays in proportion .

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98_bmw_running_compression_marked_ANNO_wave.gif (103 KB | )

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lbarron

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Re: firstlook
Reply #16 - May 8^th, 2007 at 1:21pm

hey, here is a simple capture of a 4 cylinder engine, FLS in exhaust and triggered on the common HT king lead. cyl no 4 plug lead is half off as is obvious from the trace. all the valves are in good condition as far as i am aware as this test was performed on my car which runs fine. is there anything characteristic about the trace? surely the exhaust valve opening should be matched by a positive pressure pulse? is this to be expected or do the ocsillations in the pipe mask this?

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firstlook_exh_mis.gif (21 KB | )

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mwebb

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Re: firstlook
Reply #17 - May 8^th, 2007 at 3:41pm

my first thoughts were wrong .

have you tried using a 10" rubber tube on the FLSe , i made a 10" length starting with 4" of 10mm then 4" of 1/2 " then 4" of 3/4" tube to make what looks kinda like a trumpet , to clean up the hash in the exhaust pulses .

it looks like the misfire signature pulse in the exhaust is delayed because your spark timing is very advanced ? how does that look with no loose spark plug wires ?

---------------------------------- firing order 1342 assumed .

here is a similar waveform of a ABA 2.0 jetta , #4 wire is pulled back a bit to induce a misfire . the green verticle cursors are inserted at 180 degree intervals to take up 720 degrees to make it easier to see when the exhaust pulse IS happening . i have SWAGed allowed a little for ignition timing advance .

a new feature in ANNO wave .

i wait now for Wilf to show me my error ....

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« Last Edit: May 8^th, 2007 at 9:12pm by mwebb »

2_0_ABA_jetta_Ign_misfire_on_cyl_4_5_vert_.gif (111 KB | )

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mwebb Senior Member Offline Posts: 162 Gender:	Re: firstlook Reply #18 - May 8^th, 2007 at 9:37pm i have taken the liberty to mark off your waveform , i did not label any except the exhaust pulse but it would be Power Exhaust Intake Compression 180 degrees for each total 720 degrees but the valves open & close near to those #s not at those #s now i will try to apply those cursors to RB 's 8 cylinder waveform
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lbarron

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exhaust valve operation
Reply #19 - May 12^th, 2007 at 5:07am

Hello, i have been having a play with my firstlook sensor in the exhaust. I am trying to learn which stage in the cycle each pressure pulse is due to. this test was performed on my single cylinder, 4 stroke, yamaha 125cc motorbike. There appears to be one spark for each 360 revolutuion with one spark at the end of the exhaust stroke (the one with the lower firing KVs due to the lack of compression. . .)
This test was carried out under load at medium revs.

Am i right in thinking that the first positive pressure pulse is due to the exhaust valve opening and the pressure created by combustion being expelled into the exhaust pipe?

There is a second postive pressure pulse about 10ms after, is this the pressure created by the piston pushing the spent charge out of the cylinder? this makes sense to me as the second spark fires at the end of this pulse, indicating that the piston is nearing TDC. . .

finally, what do you think about the negative pressure pulse after the two positive ones? is it due to the relaxation of the sensor's diaphragm, or the inertia of the exhaust in the pipe causing a depression or could they be due to valve overlap? . . .

I get the same characteristic trace at idle but the pressure pulsations are not as high due to the reduced volume of charge in the cylinder.

i thought that this may make the trace easier to dicipher as there are no other cylinders making any contribution to the pressure in the exhaust.

Thanks for any replies,

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under_load.gif (17 KB | )

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mwebb

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Re: firstlook
Reply #20 - May 12^th, 2007 at 7:32pm

useing the ANNO wave program from AES version 1.5.9
i have included the blocks from the Tom Clozza vacuum article with vertical cursors to mark off each 180 degrees of engine rotation. one block of
intake compression power exhaust shows 720 degrees of engine rotation as marked by the 2ndary spark waveforms .
i used the actual start of the exhaust pressure pulse as a reference to line up the blocks .

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125_cc_motorcycle_5_vert_TC_.gif (80 KB | )

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lbarron

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cranking
Reply #21 - May 14^th, 2007 at 11:33pm

heres a trace captured from my single cylinder 125cc motorclcle again. (4 stroke)
the firstlook sensor is in the exhaust, triggered on the HT lead. it appears that once the exhaust valve opens, there is a drop in pressure in the exhaust. (a negative pressure fluctuation) is this the case or am i being confused?
in the example of this test given in the Pico software a similar trace is reported.
is this one of the reasons that when you get a missfire, the pressure drops off (neg pressure pulse as the exhaust valve opens?)

thanks again for any light on the subject. . .

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crank_open.gif (14 KB | )

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mwebb Senior Member Offline Posts: 162 Gender:	Re: firstlook Reply #22 - May 16^th, 2007 at 11:54am what is different ? it is not running here ? 400 rpm ? FLSi ?
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lbarron

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Re: firstlook
Reply #23 - May 16^th, 2007 at 11:57pm

oops, i left that bit out! this was a cranking test. When you see the drop in pressure, can you confirm that that is when the exhaust valve opens? is the slight rise after the initial drop due to the piston pumping the air from the cylinder? sorry if i seem silly, i just want to ret a solid understanding of which parts of the trace represent which parts of the engine cycle and this single cylinder example simplifies it.
Thanks!

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mwebb Senior Member Offline Posts: 162 Gender:	Re: firstlook Reply #24 - May 17^th, 2007 at 10:13pm you do not seem silly , none of us were born knowing how to rollerskate and yet somehow we learned . i rollerskate well but it took me years to learn . i still fall . mistake here in this image , do you see it ? you need ANNO wave by AES
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lbarron

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Re: firstlook
Reply #25 - May 28^th, 2007 at 8:25am

this is a trace of a 4 clyinder engine at 2500 rpm. the engine has twin static ignition with the plugs firing 1&4, 2&3. i disabled injector number 4. (firing order 1342)
i used the primary earth for 1&4 plugs, at least according to the wiring diagram i did!
do you rekon this is correct? it almost appears to be a misfire on injector number 2. . .
what do you people think?

i just dont want to get confused over this!!
thankyou

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2500_inj_miss.psdata (257 KB | )

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lbarron Freshman Member Offline Posts: 11	Re: firstlook Reply #26 - May 28^th, 2007 at 8:39am . . .and here is the same car with the same problem viewed at idle, the two traces just don't seem to cohere with each other. . . is there anything obvious that i am overlooking. . .
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mwebb

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Re: firstlook
Reply #27 - May 30^th, 2007 at 10:20pm

Quote:

. . .and here is the same car with the same problem viewed at idle, the two traces just don't seem to cohere with each other. . . is there anything obvious that i am overlooking. . .

here is my interpretation of SOME of what is going on here . i dont see where the fuel could have come from that caused the extra pressure in exhaust puff for cyl #2 unless the injector for # 4 is leaking . since nothing was synced i am guessing on the sync . weak exhaust puff = no fuel = disconnected injector on #4 ?

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cyl_4_injector_disconnected_idle_.gif (97 KB | )

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mwebb Senior Member Offline Posts: 162 Gender:	Re: firstlook Reply #28 - May 31^st, 2007 at 8:15pm here is a screen cap of some of the active cursor options in ANNO wave ,
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mwebb Senior Member Offline Posts: 162 Gender:	Re: firstlook Reply #29 - Jun 9^th, 2007 at 7:38pm so , here is another thing ANNO wave can do , this is relative compression from 4 cylinders stacked up after the size amplitude and length has been adjusted such that they all displace the same amount of screen for 720 degrees .
Back to top	96_accord_relative_compression_stack_ANNO.gif (79 KB \| ) IP Logged

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