Wrong reading of engine speed when Pico is connected

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Re: Wrong reading of engine speed when Pico is connected

Postby victor2k » Thu Dec 29, 2016 9:12 am

Hello,
Using the wiring diagram on CH A I measured NE+(pin 78/B) vs NE-(pin 77/B),on CH B I measured G+(pin 80/B) vs G-(pin 79/B) as is specified in the repair manual,but not selecting AC coupling. :(
For the injection I monitored the injector driver supply (I need to see if some injections missing).
For the rail pressure I measured pin 67/B vs the engine ground.And only this signal isn't dirty so I need to find an answer.I used the recomended connection points but my device was influenced ECU(I can see rpm without engine on).
Thank you.
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cam vs crank 2ad.png
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Re: Wrong reading of engine speed when Pico is connected

Postby STC » Thu Dec 29, 2016 11:45 am

Hi Victor.

That looks like a Toyota test plan. I have yet to come across a VM test plan that is complete and conclusive. Most just want you to replace the ECM if "their" idea of testing does not find the fault.

According to your picture you should have Injector durations of 8-10 mS on a warm engine at Idle, a diesel injector firing at under 5 volts and your Cam and Crank are Not Synced. Very poor illustrations and nonsense in real life !!!

2007 RAV4/2AD engine type with some staring issues


I would treat that as any other Diesel with starting Issues and start at the beginning with the basics
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Re: Wrong reading of engine speed when Pico is connected

Postby KimAndersen » Thu Dec 29, 2016 11:34 pm

Hi Victor

After a close study of your post and your psdata file I've come a little closer to understand what your are trying to measure.

Well, without a diagram you are lost and after some searching in my achive, did I find the right diagram.

Did it have a DTC like P0200 ( Open or short in EDU or injector circuit ) which has something do with injection confirmation (INJF) signal you are trying to measure on pin terminal B32(51) and B32(109) !!!

BTW the injection confirmation (INJF) signal look very weird to me - it was here that I couldnt find any meaning with this waveform - I thought it was the output signal from the EDU driver to the injectors since you had measured it with a current clamp.

The injection confirmation (INJF) signal should be a clear square wave signal - try measure it again, but this time as voltage signal.

Also measure the output signal to injectors with a current clamp around every single wire IJ1+,IJ2+,IJ3-,IJ4+, as seen in this wiring diagram.

INJECTOR_EDU_DRIVER_CURRENT.jpg


Regards
Kim
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Re: Wrong reading of engine speed when Pico is connected

Postby victor2k » Fri Dec 30, 2016 3:00 pm

Hello,
Monitoring the supply of EDU with clampmeter you will see all 4 injections...or a missing injections on some cylinders.
The battery is weak(This was the reason for supply curent monitoring and not INJF),also the SCV of fuel pump sometime is blocked.I must use TSB EG-0132T-1110-EN to solve this issue.
I have RM and wiring diagram but my signals isnt't like in repair manual.Also here is a part of a advanced diesel diagnose from TME(image attached) using Pico.The same setup is used...
But the question from the first post is the same :why I have some "noise" on cam & crank signals(even if the ECU input is biased by my Pico,this must rise the level of signal ).AC coupling will remove only continuous bias ,not ac "noise".Only if the ECU is unstable with the new bias...I must try again with AC/DC coupling on the same car.
On a working engine the signals will be clean and nice but sometimes we need to understand some strange signals what can't be find in RM :?
Thank you.
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Re: Wrong reading of engine speed when Pico is connected

Postby STC » Fri Dec 30, 2016 9:52 pm

With regard to the noise
Noise Delete.jpg


What happens in between the arrows, something is making that noise go away and come back ?
The Amplitude / Shape of the noise is directly related to the Blue CKP signal.

Do you still get that noise if you scope CMP with the Ignition Switched Off and exciting Terminal 50 to get rotation, try it with the CKP disconnected too.
Last edited by STC on Fri Dec 30, 2016 10:09 pm, edited 1 time in total.
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Re: Wrong reading of engine speed when Pico is connected

Postby victor2k » Fri Dec 30, 2016 10:06 pm

Don't know what can make this noise.514 Hz...maybe suction control valve? :shock:
I didn't see until now this noise...
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Re: Wrong reading of engine speed when Pico is connected

Postby STC » Mon Jan 02, 2017 11:16 pm

There are 2 lots of interference going on both at the same frequency. The you have another at 7Hz on the Green Injector line before you start cranking. That too disappears then comes back.
delete rav 4.png


I would start by taking away any laptop or car battery chargers, maybe cut all the power in the workshop at the main switch just to confirm that it is the car and not external.
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Re: Wrong reading of engine speed when Pico is connected

Postby victor2k » Tue Jan 03, 2017 10:01 pm

Hello,
No charger was used with the laptop or the car battery.
I suspect ECU for this strange noise,also for the charging lamp what blink at every 5 seconds with ignition ON(and this is happens without any wire/back-probe pins connected).On this car the charging is controlled by ECU.
I will make some new captures .
Thank you
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Re: Wrong reading of engine speed when Pico is connected

Postby EAAD » Thu Feb 09, 2017 11:58 pm

Re: Wrong reading of engine speed when Pico is connected

Postby Autonerdz » Wed Dec 28, 2016 8:35 pm

The help guide from Picoscope should the first starting point



We struggle every day trying to get techs to avoid using the automotive menu. We find that it creates more problems than it helps with. Those that start there have to re-educate.

Here is one recent example of when this spilled over into our public boards. Free membership is required to follow this link.

http://www.autonerdz.com/cgi/yabb2/YaBB ... 1470695090

Coupling that signal to AC will hide that essential information.



Absolutely. I learned this decades ago when working with an analog ABS problem. One wheel would code but all sensors displayed identical waveforms AC coupled. As soon as I chose DC, the problem was obvious. The coding wheel had a much higher bias voltage which led to the solution. Again, the automotive menu instructs you to AC couple these. Wrong.

AC coupling is often used for alternator ripple so you can filter out the DC and see the AC riding on it better but using a lower scaling. But with Pico's awesome zoom and filter capabilities, there is nothing that needs AC coupling.

I don't want to derail this thread so I will shut up now.... :wink:



Just a line from me, having watched Jan17 Group Therapy & conducted a few tests, Tom is bang on correct on this.
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