TOP ISSUE...

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autobrejo
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TOP ISSUE...

Post by autobrejo » Fri Aug 09, 2019 7:26 pm

Hello everyone, I'm Tiago from Portugal,
I've got on my garage a funny problem, the car is a IBIZA 2008, 1.2 simos, when i read the codes i found a misfire on cylinder 1 i change all sparks(3) and coil (3) but the problem does not disappeared , i read the voltage vs current of all injectors , synchronize the signal of injector, coil, crankshaft and camshat sensor knock sensor .... but i did not find any problem...i i save all waves i study one by one, and i have a question on voltage vs current of injector 1. before and after the signal, we can see a small signal on voltage and at the same time on current, can anyone tell me if was normal?
Attachments
inj current nº1.psdata
(18.09 MiB) Downloaded 36 times

Technician
TwoWaves
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Re: TOP ISSUE...

Post by Technician » Sat Aug 10, 2019 12:40 pm

Hi, do the test again but increase the settings for the current on channel B. It looks like the settings at about 0.7 A are too low.

vasek
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Re: TOP ISSUE...

Post by vasek » Sat Aug 10, 2019 1:19 pm

autobrejo wrote:
Fri Aug 09, 2019 7:26 pm
i have a question on voltage vs current of injector 1. before and after the signal, we can see a small signal on voltage and at the same time on current, can anyone tell me if was normal?
This is the right signal.
Perhaps there is a problem with the mechanical part of the engine.
Either there is air leak in the area of the first cylinder or the PCV system.
As a result - uneven operation of the engine at idle.
The ECU tries to align the engine by supplying an additional injection in addition to the main one.
Due to the short pulse time,the current does not reach its maximum value.
There is no characteristic point of closing the nozzle needle.
.
This mode of operation is typical not only for SIEMENS, but also for other manufacturers.
Here's an example of the extra injection on FORD.
Attachments
FORD FOCUS II 2.0 AODA MPI - AN ADDITIONAL INJECTION.PNG

ronw38
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Re: TOP ISSUE...

Post by ronw38 » Sat Aug 10, 2019 11:18 pm

Hi Autobrejo Concentrate on the fuel trims at idle and steady 2500 rpm Long term should show as a stored Pid value if there is persistent mixture problem , live data both S/T and L/T will show if you have a rich or lean condition thus help narrow your path eg [spark tracking out] rich condition . Cheers Ron

KimAndersen
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Re: TOP ISSUE...

Post by KimAndersen » Sun Aug 11, 2019 11:17 am

Hi autobrejo

There are something odd or strange with this injector waveform you have taken.

Firstly - I don´t think you amp probe are reset correctly if you ask me. There shouldn´t be any current draw when the fuel injector isnt switched to ground - you have around 182 mA , so try to reset your amp probe again.

Secondly is there issue with the polarity on the voltage measurement !. When you look at waveform capture again its clear to see what happens when the fuel injector is switched on - the injector voltage is pulled down to minus 27 volt DC - that dosen´t look right.

SEAT_IBZIA_INJECTOR_WAVEFORM.jpg
SEAT IBZIA INJECTOR WAVEFORM MINUS 27 VOLT DC

This may be something with your picoscope - I really dont know.

Another thing I did notice when I looked through the frames of your picoscope file was frame 7.

Frame 7 seems to be missing its injector signal for around 10 milli second (mS) - it could be a glitch in this particular picoscope capture - its hard to say whether this is issue or not.

If this frame is missing constantly - then its a problem.

Have you looked in the waveform libray for that particular engine type !. :wink:

Regards
Kim

Iver
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Re: TOP ISSUE...

Post by Iver » Mon Aug 12, 2019 8:16 pm

You got a 4 Channel Scope there

Can we see Voltage & Current on Bad Cylinder then Voltage & Ground on another Cylinder.

And time across screen is to short. Lets have it at 1 second per division so 10 seconds across screen. At least 10 Screens.

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autobrejo
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Re: TOP ISSUE...

Post by autobrejo » Wed Aug 21, 2019 3:37 pm

hello again, there is the wave oh ckp and cmp
i see on ckp some peaks on wave can you give me your opinion?
Attachments
Seat_Ibiza_2008_Petrol_20190821-0001.psdata
(13.8 MiB) Downloaded 21 times

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autobrejo
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Re: TOP ISSUE...

Post by autobrejo » Fri Aug 30, 2019 12:08 pm

hello again after many tests and studies i found something to explain on absolute compression of cylinder nº1
on intake stroke its was normal some pressure oscillation when the piston go down? the intake valve is open, the piston is moving down, so, why we have oscillation?
Attachments
absolute compressure cylinder n1.psdata
(67.19 KiB) Downloaded 28 times

victor2k
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Re: TOP ISSUE...

Post by victor2k » Fri Aug 30, 2019 5:21 pm

Hello,
Have you ever heard an echo, the same phenomenon occurs in your case too.That is why the intake manifolds have certain shapes, the piston ends as well ... for air flow optimization,for better filling of the cylinders :o
Best regards

kona
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Re: TOP ISSUE...

Post by kona » Sat Aug 31, 2019 4:57 pm

Answer to your question:
vasek wrote:
Sat Aug 10, 2019 1:19 pm
........
Perhaps there is a problem with the mechanical part of the engine.
Either there is air leak in the area of the first cylinder or the PCV system.
........
Your waveform confirms this:
Attachments
2019-08-31_193320.gif

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