Fiat Doblo non-starter

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MartinA
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Joined: Mon Sep 03, 2018 10:39 pm

Fiat Doblo non-starter

Post by MartinA »

Hi
I am having one non starter Fiat Doblo 1.4turbo CNG. I have capture of in cylinder with injector pulse, ignition pulse and crankshaft, but this is my first in cylinder waveform so i dont have enought experience.
it looks ok to me but i will be gratefull for some advice. The only thing that i dont like is where the injection is happening.
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doblo.part2.rar
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doblo.part1.rar
(18 MiB) Downloaded 55 times

vasek
TwoWaves
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Re: Fiat Doblo non-starter

Post by vasek »

Hi.
The ignition timing is very late.
Much later than the TDC.
This is probably due to a mechanical shift of the reference disk.
.
The engine speed when rotating the starter is approximately RPM=120 , this is not enough.
When the crankshaft rotates slowly, there is some difference between the actual compression point and the TDC according to the pressure sensor.
But even so, the timing is out.
The spark ignition occurs at about 16th pulse after skipping.
The ignition advance on the starter rotation rarely differs from the value 0...+5.
This is where the TDC is located.
In the example shown, the peak pressure on the sensor falls on the 12th pulse.
Check engine mechanics.

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MartinA
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Re: Fiat Doblo non-starter

Post by MartinA »

Hi Vasek
thank you for your reply
The timing is good its checked with tools. the reference disk for the crankshaft signal is the crankshaft pulley itself and its on spot too there is some sort of key way there. ive compared cam, crank, fuel injector and coil signal signals with known good from working car and they are like mine only the fuel is way off. I compared the file from ecu for some tunning but its stock too.

know good capture is with 780RPM on idle
Attachments
known good doblo2.png
known good doblo1.png

vasek
TwoWaves
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Joined: Tue Feb 17, 2015 7:27 pm

Re: Fiat Doblo non-starter

Post by vasek »

The fact is, that very often the timing of the injector at starter speeds ,differs from the timing at RPM idle and at medium speeds.
You need to make sure ,that the actual position of the piston in the TDC ,matches the marks on the pulley.
.
You can look at it this way.
The decrease in the amplitude of the inductive sensor occurs at the point where the minimum speed of rotation of the crankshaft.
The rotation speed is minimal at the compression point.
It turns out that the ignition is very late.
In this case ,the ignition corresponds to the pulse on the reference point of the crankshaft,
but does not correspond to the actual TDC:
Attachments
TIMING NG.png

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MartinA
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Re: Fiat Doblo non-starter

Post by MartinA »

Yes i checked that, mechanical top dead center checked thru the spark plug hole is corresponding to the 11th teeth after two missing teeths. and yes the injection and the fuel is changed with the rpm but cam and crank are the same with working one. tommorow i will have working doblo with me and will capture everything again with disabled fuel pump. what is triggering fuel injector signal location?

kona
TwoWaves
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Re: Fiat Doblo non-starter

Post by kona »

MartinA wrote:
Fri Apr 16, 2021 5:43 pm
.... and will capture everything again with disabled fuel pump. what is triggering fuel injector signal location?
The first thing you need to do is check the belt ! :!:
It is clear from the diagram. what a misalignment of 5 teeth ! :roll:
Leave the pump alone.

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MartinA
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Re: Fiat Doblo non-starter

Post by MartinA »

hi :)
yes indeed it was 5.5 teeth out. This engine cant hit valves and to replace the toothed belt of this engine it is only necessary to remove the ribbed belt pulley and no one saw the problem.
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video-1dd669cf57f276f26656618625c15902-V.mp4
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IMG-8447c9dc23423c6b76506d8d78edb963-V.jpg
IMG-c054cb2e1b47d4ca80733960b5b5bf55-V.jpg

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