compression and spark timming question lab scope

[normanatlm]

just picked up my eepv302at 500 psi transducer, so giving it a road test.
want to figure best way to check compression and spark fire for that cylinder, not exactly sure if I am doing this correctly, any input would be apreciated.
I was using the eems301a05 split lead adapter, and a inductive rpm pick up, as well as the transducer on ch1.
was working on a 02 buick rendevous with 3.4 motor, pluged the secondary wire into a spark tester and grounded to block, put inductive rpm clamp on the ignition wire.

don't know if it matters but channel 2 was set to 20 amp low probe ????
channel 1 250 psi, 500 psi transducer.
so this is the screen I got, my question, is this? Is the ch2 big spike, right before the peak on channel 1, the spark fire, indicating that it fired right before tdc? and is this the best way to check?

I do have sia 2000, low amp and hi amp probes, and eetm306a02 sec ignition clip on adapter.
any inputs, thank you.

[kebo1970]

transducer

if you go to aeswave.com you can buy the software for $40 that will give you all you need along with running compression results. put channel two on kv instead of amps if you have a spark plug wire to grab on to. your picture looks good though. the software will let you know how many degrees before top dead center the spark occurred. this is useful when dealing with timing issues

[normanatlm]

if you go to aeswave.com you can buy the software for $40 that will give you all you need along with running compression results

yes I like aeswave, I have there "exploring combustion behavior" by Mac Vandenbrink, and "mastering low current probes"
only draw back is they jump from meter or diag tool to another, have invested a small fortune in snap on, so I prefer to view snappy products and support info, when possible.
what software from aes do you recomend? and is it modis specific?
thank you

[crackerclicker]

i recommend you get a "sync probe" from aes or use your ignition probe instead of the rpm clamp.

as for tdc, be careful what you decide is true top dead center when doing in-cylinder testing. here's a good link to keep in your favorites:

http://members.iatn.net/forums/search/search.aspx?action=viewthread&m=34951&t=34951&forum=forum13&ft=1&fv=4&qv=1

[kebo1970]

this software lets you use your transducer to capture in cylinder pressure readings and transfer them to a pc. then you can use the overlay function to determine if a timing belt or chain is off a tooth or two. you can check ignition timing also. go to aeswave.com. where it says search store type in tdc and then hit go. from there you can read the info; the software is for modis and other scopes as well. you will need shopstream connect in order to use it with the modis.

[normanatlm]

this software lets you use your transducer to capture in cylinder pressure readings and transfer them to a pc. then you can use the overlay function to determine if a timing belt or chain is off a tooth or two. you can check ignition timing also. go to aeswave.com. where it says search store type in tdc and then hit go. from there you can read the info; the software is for modis and other scopes as well. you will need shopstream connect in order to use it with the modis.

yes I viewed tdc at aeswave last night, put it on my to get list
here is snap shot with ch2 set to kv and using inductive rpm pick up
thanks

[normanatlm]

i recommend you get a "sync probe" from aes or use your ignition probe instead of the rpm clamp.

as for tdc, be careful what you decide is true top dead center when doing in-cylinder testing. here's a good link to keep in your favorites:

http://members.iatn.net/forums/searc...ft=1&fv=4&qv=1

thanks for the link

[crackerclicker]

use your ignition probe instead of the rpm clamp.

actually, i'm not sure this would work. can you use ignition leads when you are in lab scope mode? haven't had a snap on scope for awhile now, and i don't remember. the synch probe is better than your rpm probe, but i see it seems to be reliable.

image below, in the upper screen, is a synch capture. a good one can be found here: http://www.aeswave.com/Products/Product.asp?i=532

[normanatlm]

actually, i'm not sure this would work. can you use ignition leads when you are in lab scope mode? haven't had a snap on scope for awhile now, and i don't remember. the synch probe is better than your rpm probe, but i see it seems to be reliable.

image below, in the upper screen, is a synch capture. a good one can be found here: http://www.aeswave.com/Products/Product.asp?i=532

don't believe I can use the sia 2000 in lab scope or use it with psi transducer.
I like the screen you got with synch probe, not sure if banna plugs would work with snappys psi transducer set up? maybe use a channel 3 or 4 perhaps.
maybe monday experiment more with this.
what is easiest way to do this with a cop system? just run a secondary wire out of the cop?

thanks

[crackerclicker]

what is easiest way to do this with a cop system? just run a secondary wire out of the cop?

thanks

depends. if it's a cop with an internal transistor then just use the command pulse from the pcm (or whatever device that's controlling it). if it's a normal 2 wire cop simply use coil negative to capture primary volts.

ps. that capture above is a known bad.

[normanatlm]

love these snap on toys, the more I use em.
got a 95 bmw 525i in today, customer thought shutter when accelerating was bad trans. scanned code for cyl 3 showed up
ckd with sia 2000 and a flag, cyl 2 and 3 no burn time, bad pattern, used low amp probe and both injectors were good, compression good, swaped # 2 cop to cyl 1, now cyl 1 no burn tme, cyl 2 ok.

2 bad cops

[normanatlm]

love these snap on toys, the more I use em.
got a 95 bmw 525i in today, customer thought shutter when accelerating was bad trans. scanned code for cyl 3 showed up
ckd with sia 2000 and a flag, cyl 2 and 3 no burn time, bad pattern, used low amp probe and both injectors were good, compression good, swaped # 2 cop to cyl 1, now cyl 1 no burn tme, cyl 2 ok.

2 bad cops

patterns

[salvaje07]

You can measure your degrees using the cursors. From peak to peak compression stroke is 720 degrees and divide it by the time measured by the cursors. The spark should occur at or before TDC. There is some good transducer articles at Automotive Test Solutions. (atsnm.com) They break it down really good. Using the transducer for running compression test works great.