Thread: SXE-Probe VFP1000 Oscilloscope & Digital Multimeter

Here is the attachment for the SXE-Probe Video Part II, which details the pulse and the Hz/Frequency (pulse per second)

LRT

I will have to post SXE-Probe Video Part III tomorrow or later this week. LRT

Here is the attachment for the SXE-Probe Video Part II, which details the positive period of one pulse cycle, which is called the duty (%).

LRT

Here's my take on it, but as I don't know the tool so someone may need to fill bits in or correct me.

The video unfortunatly does not prove or disprove the itegrity of comms (I'm assuming this is the comms line) between the ECM and BCM. What it does prove is there is activity on the line. But not that it's good. With the right tools that may be possible, it may even be able to decode it (if you can work out the protocol and speed) although without the right info (verging on impossible to get) you won't be able to work out what information is actually being sent.

But.......
I believe the problem lies solely (barring a really obscure fault) with the engine management not with anything else.

If I remember correctly, the fuel pump is working and the PCM is trying to fire the injectors. Something a PCM does not want to unless it thinks the engine will fire (cat damageing and floods the engine).
Frequency and duty cycle info would of been of some, but limited help. Just to get some sort of idea of what the PCM is injecting.

When you test the coils, you got a frequency but no duty cycle. That did not make sense to me. The frequency tells us something has happened and it occured approximately the correct number of times for a engine cranking.
But the duty cycle (I think that was your second figures) tells us nothing happened. Does not make sense.
I believe the PCM tried to fire the coils but could't and the probe is not giving the full story.

So in a nutshell I believe the issue is only with the PCM and is on the ignition side of it. And something that effects all of the coil drivers. A bad earth is what comes to mind?????? You really need to know what the drivers are doing.

Not much help, just my take on it which could be way off the ball park.

I think I came across as if I'm trying to discourage you. Not at all.
I just want to point out with out the right gear it can be next to impossible to find a fault and become very expensive. You need to follow a direction and not drift too far off it.
The injectors firing tells me the PCM is at least half happy with what it got. Assuming they are not getting triggered randomly, although that can be caused by poor connections too.

Here's an example of a DI than had a intermitant no start, always long crank, and occasional cut out.
The guy had given up trying to drive it.
It had 1 distributor, 3 coils, 1 cam and two sets of heads. Lots of subsition parts tried, spent many weeks at a Land Rover workshop with even the offer of converting it from EFI to carby to fix the problem.
Which it wouldn't of!!..



And zoomed in on a no ignition event.



#4 should read no spark.

The top image was 2 1/2 seconds of cranking before it fired up. It was having a good day.

And for an idea of what 602us is. Its 0.000602 seconds. A life time when trying to create a spark. It should preferably be 30us or 0.000030 seconds.

No nanocom, test book or test light will find it. Some faults are not hard but can be hard to nail. And the expensive guessing. That didn't cut it either.

This is why I'd like to know what that primary ignition is doing, it may give a clue. But I don't know how you can do it.

Hi nobbyclrk,

The tests were done on the ECM-BCM communications line. I only switched the modes when testing the coils.

I now realise that the SXE-Probe is only a tool for testing to see if there is a pulse being transmitted.

As the SXE-Probe website states:

"The SXE-Probe is a superior Logic Probe combining the features of a DMM and oscilloscope but simplifying the display for technicians that want to find the pulse but don't need to see the trace signal." SXE-Probe_(VFP1000)

I clearly need to buy an entry level oscilloscope, and begin a big learning curve!

Many thanks,

LRT

Hi nobbyclrk,

Thank you for the very helpful and informative comments and examples. I shall study them closely.

It is great that you are willing to share your knowledge and wisdom, and to help others.

I am most grateful.

Regards, LRT

I now realise that the SXE-Probe is only a tool for testing to see if there is a pulse being transmitted.

That was what I was trying to say. (Putting things in plain old English is not my strong point. )
The probe will show if something is not working, but not show if something should work.

I clearly need to buy an entry level oscilloscope, and begin a big learning curve!

If you have any questions regarding specs PM me. Some of the cheaper ones will do some impressive captures but there are many pitfalls as well. A couple of specs to look out for are sample rates (the number of measurements it takes per second) and buffer size (the number of measurements it can store).
The top of the range ones will do some impressive capture. I'll put some examples up over the next week.
The learning curve is big but easily do-able. Four years ago I couldn't predict a voltage in a bulb circuit, now I have a reasonable understanding of EFI. Although when you think you have it worked out, the goal posts move. Injector duration is a classic example.

Thank you for the very helpful and informative comments and examples. I shall study them closely.

It is great that you are willing to share your knowledge and wisdom, and to help others.

Good to hear you find it informative. It's been something I've enjoyed doing for the last few years, mainly done outside work hours.

I'll try and get some other captures up next week for kicks. To be honest I think it does come across as mumbo jumbo to most . Although it's not that hard to get some sort of grips with.

Cheers