Oscilloscope waveforms of fuel pump, hall sensor, injector, spar

[Abscate]

[hans j]

I can make picoscope pretty much do what ever I want. There are math channels as well as measurements that you can do for each channel, like average rms and voltage (about 15 more). The software is free to download, so check it out. I prefer 6 over 7, but if you're new to pico, 7 might work for you.
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1986 Canadian Syncro Westy TDI - 1989 Syncro Single Cab - 2001 Audi S4 - 1981 VW Caddy ABA - 1980 VW Caddy EV - 1973 VW T-181

[davlance01]

abscate- I am definitely going to look at FFT and see how that helps, I'll post pics after I learn a little more about how to apply it. Thanks for pointing me in the right direction.

hans j- I actually did download it but I can't run it on my crappy hantek 1008c. It does allow you to scroll through the known good automotive waveforms which is helpful.
If I had the cash pico would have been my first choice but at $3200+ it just didn't make good sense. I got $100 in my hantek and with better leads, 650 amp and 65 amp clamp and 2 ht25 secondary ignition pickup and a 20:1 Attenuator I am into it for a grad total of $320. Its a good start for someone just getting started in scopes.
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Life is short and the road is long so if you want to see it all you have to drive fast!

[davlance01]

abscate- I learned a little about the FFT and I do have it on my scope software.
I can defiantly see why you suggested it especially for the fuel pump. I'm not sure why nobody ever suggested it for checking the fuel pump frequency.

Looking at my spark waves I defiantly have a fuel supply issue and the FFT will come in real handy checking my pump.

I'm real curious on what it will look like on my spark waves. I am almost afraid to see it.

I am going to put that to work and I'll start posting pics.
Thanks again for the great advice!
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Life is short and the road is long so if you want to see it all you have to drive fast!

[hans j]

I converted some of my captures to frequency and don't really see any benefit to it? A good capture and the frequency won't change much. But a bad one changes a lot. Personally, I think current and pump rpm are way more important than frequency for fuel pumps on vehicles. It might have it's place in other things, but it's not really something that I have to do.
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1986 Canadian Syncro Westy TDI - 1989 Syncro Single Cab - 2001 Audi S4 - 1981 VW Caddy ABA - 1980 VW Caddy EV - 1973 VW T-181

[davlance01]

[davlance01]

For anyone still following this topic. The scope found the issues I was having with the car.

2 bad injectors
fuel pump weak, pulling 1 amps (pressure and volume was reading fine though)
bad plug on the temp sender 2.

Car runs better than it ever has and I only purchased the parts that were needed.

My advice is everyone should own and know how to use one of these.
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Life is short and the road is long so if you want to see it all you have to drive fast!

[davlance01]

purple spark line
green hall effect
cyan running compression with pulse sensor

825 rpm
4.2 degrees ATDC

84 vanagon with a stock 1.9

BTW: the timing light shows more than 60 degrees BTDC!!!!!
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Life is short and the road is long so if you want to see it all you have to drive fast!

[DanHoug]

that's VERY cool with the compression sensor in there!!!

i refurbed an old school SUN scope that does a nice job with ignition waveforms. so much one can deduce from the those.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[davlance01]

It is a game changer for sure.

I purchased the pulse sensor because the van was loosing power the hotter it got.

I hooked it up to the exhaust and seen my #2 exhaust was hanging open.

Turns out it was the clip that holds the hydraulic lifter together was missing and the lifter was pushing itself apart in the block.

How long do you think it would have taken me to find that little problem without a scope? It took longer to drain all the lifters before I put them back in than it took me to diagnose the issue.

Frankly I have no idea how these guys diagnose these vans without one.
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Life is short and the road is long so if you want to see it all you have to drive fast!

[hans j]

Yeah it's pretty cool. But your pressure sensor doesn't appear fast enough or might not be rated for in cylinder it looks like. This capture is using a Pico WPS500X and it is designed for that use as well as low pressure vacuum since it has three different pressure transducers inside. I use it for fuel, oil, in cylinder, intake, exhaust, coolant, and crankcase pressures. Pretty much anything except brake and power steering fluid (due to the pressures).

Delta sensors are extremely useful too (I use First Look Sensors and home made versions), but they only measure a change in pressure. They work faster than a transducer, but don't measure any actual pressure. These are useful in looking at mechanical cylinder contribution. However I've found on a WBX engine, even when the valves are properly setup, there is still uneven pulls and pushes in the intake and exhaust like this one shows.

Yes these tools are extremely useful, but have a place. I did have another shop in town condemn an engine and quoted a replacement for it. Sure enough this engine didn't have compression on two cylinders using a traditional gauge. But when I hooked up my scope, I found another story. The valves needed adjusting and it needed an oil change. After that work had been done, the engine ran great.

Another thing with these tools is few shops have them, and even fewer techs know how to use them. Toyota dealerships are required to have a Pico and WPS for testing cars, but few techs will touch them. In fact there are several OE's who use Picoscopes as their factory tooling. And if you are using Windows 10, look up the Pressure Waveform Overlays app. It will show you even more cool stuff.


Link


This is an abbreviated version of an 8 hour class I've taken. If you look up the other CTI videos and their virtual classroom, you'll find lots of information on it. It's pretty awesome stuff when you have time to mess with it!
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1986 Canadian Syncro Westy TDI - 1989 Syncro Single Cab - 2001 Audi S4 - 1981 VW Caddy ABA - 1980 VW Caddy EV - 1973 VW T-181

[djkeev]

[Abscate]

This is an awesome thread and needs bookmarking in the Vanagon FAQ AREA
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.ssS!

[djkeev]

[davlance01]

hans_j...
Nope its not even close to being rated for in cylinder pressures so I 3d printed a venturi effect adapter for my first look sensor and what you are actually seeing is vacuum not pressure. I just needed TDC and not actual pressures so sometimes you work with what you have.

But I really really really want a Pico WPS500X, those are professional grade.

I'm still using the infamous hantek 1008c I paid $80 for. The thing is a tank and it doesn't have all the bells and whistles of a pico but it gets me going in the right direction.
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Life is short and the road is long so if you want to see it all you have to drive fast!

[davlance01]

hans j...

Please explain the pic with the intake and exhaust pulses.

Is the green exhaust and blue intake?

Are you running a aftermarket ECU? (vanagons don't have coil on plug)
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Life is short and the road is long so if you want to see it all you have to drive fast!

[davlance01]

My before and after exhaust waveforms with fix....

diagnose (car loosing power when hot, have to hold petal to the floor most of the time just to keep going. no backfires or odd noises just no power)

waves before fix

exhaust wave

intake wave

diagnoses...
Odd pattern in the num 1 and 2 exhaust pulse
num 1 intake not closing (or opening) all the way.

Removed valve cover for cyl 1&2 head while hot and pressed in the rockers and all had some movement but the num 1 intake was hard as a rock.

Removed the rocker arm and push rods and seen that the num 2 exhaust lifter was missing the clip that holds it together.

repair...
removed all 8 lifters, disassembled and cleaned.
replaced missing clip (fabricated a new clip)
installed lifters dry and preloaded each lifter with 2 turns of the adjustment screw.

after fix exhaust wave with engine at operating temperature.

test drove and no more power loss.

Power loss issue resolved and no parts needed purchased.
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Life is short and the road is long so if you want to see it all you have to drive fast!

[hans j]

[Abscate]

Did you source and document the pressure sensor up thread or did I miss it?
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.ssS!

[djkeev]

Added to FAQ under "tools"

https://www.thesamba.com/vw/forum/viewtopic.php?p=6236040#6236040

Dave
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