ford fiesta vibrations to the engine

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Emanuele.Vag
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ford fiesta vibrations to the engine

Post by Emanuele.Vag »

Good evening to everyone, this ford fiesta b299 1.5 tdci engine code UGJC has some vibrations (or rather some jerks). it does not have DTC, from the analisis conducted hte vibrations seem to come from the turbo pressure that comes and goes.
I visually checked the turbo for signs of wear or blockage, all OK.
the vibrations seems to be caused by the wastegate solenoid valve which suddenly increases and decreases the duty cycle.
The problem is very accentuated with the 5th gear with the other gear seems to go well.
I apologize in advance for my english ( i'm italian) i thank those who can give me an idea im am at crisis, what that behavior of the wastegate solenoid could depend on.
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ford fiesta 4.PNG
ford fiesta 2.PNG
ford fiesta.PNG

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Grant_Baker
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Re: ford fiesta vibrations to the engine

Post by Grant_Baker »

I see you scoped the MAP Sensor and wastegate position sensors. This seems like wise choice.

Your screen images show your math channel is on CH A. But, your channel labels show Duty Cycle on B. The gold trace(math channel) seems useless as a result of selecting A instead of B to formulate the math channel. Also select a different color for the math channel to avoid confusion.

Care to send us the .psdata file?

Emanuele.Vag
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Re: ford fiesta vibrations to the engine

Post by Emanuele.Vag »

so I made a mistake, in practice I changed the mathematical channel only that I did not change the name in practice the mathematical channel is of channel B. i wanted to.send the channel.psdata but it tells me it's too big

Steve Smith
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Re: ford fiesta vibrations to the engine

Post by Steve Smith »

Hello and thank you for the posts

Reading through your initial post the word "crisis" made me smile as I know only too well that feeling of loneliness and gloom when you hit a brick wall with diagnosis
One thing we cannot have is a technician in crisis and your English is fine

Looking at your captures remined me of this case study viewtopic.php?p=100270#p100270

These studies maybe totally unrelated but in my scenario manifold pressure was great than exhaust back pressure and when the EGR valve opened (low load, light throttle cruising) this would result in intake manifold pressure venting into the exhaust system creating a surge/jerky drive (sudden drop in MAF)

Blocking the EGR during diagnosis confirmed the fault and cleared the symptom and so this may be an avenue to explore (obviously this would have to be un-blocked and the fault rectified)

With the Alhambra case study we arrived at turbocharger boost level remained too high at light load but were not given authorization to replace

I therefore don't have a conclusive diagnosis but I hope this serves as food for thought?

Take care.....Steve

Emanuele.Vag
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Re: ford fiesta vibrations to the engine

Post by Emanuele.Vag »

Hello I had time to devote myself a little to this machine. I tried to check on the road with the parameters of the other day and in addition the position sensor of the egr valve during the vibrations the egr is closed. furthermore, as a counter-check, I temporarily disconnected the egr and the vibrations are still present. I am confused and I do not understand how ever the duty cycle of the wastegate behaves like this.
ch A map sensor, ch b wastegate sensor, ch c egr valve position sensor
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fiesta.PNG

Dcunning35
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Re: ford fiesta vibrations to the engine

Post by Dcunning35 »

Have you looked at the egt sensor temperatures serially or the voltages when the vehicle exhibits the juddering?.
I have seen seamingly inappropriate shifts in the turbo solenoid and egr valve commands when the Dpf is about to go over temperature or there is a disparancy accross two sensors. This can be caused by residual HC,s built up of the front face of the oxidation cat or even cracking in the Dpf substrate which avoids logging p2002 .
It might just be worth a look

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