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Discussion Starter #1
Yesterday while I was driving I noticed my car was revving up and down by itself as if an invisible foot was controlling the throttle when in neutral.

It would idle at below 1000rpm then after a short time rev up to around 1500rmp and then drop back down to normal levels (below 1000rpm) but would continue this behaviour till back in drive. At times it would be fine.

Just wondering if this could be just bad fuel or something that need checking out.

Car is 2014 Sportivanav 170 TCT. Owned from new, only 9500k on clock.
 

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This happened to me as my battery was dying. Revving on it own. But then eventually the transmission would stay in second gear and refuse to change. It was all down to the battery. Any chance you're suffering the same?
 

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Discussion Starter #3
Car isn't even 2 years old yet. Think battery is in pretty good condition, only done 9500k and stop start is working so the charge level must be pretty good. Tried it this morning and it seems to be fine. I wonder if the heavy rain and wind I drove though on Monday did something to one of the sensors and something needed drying out. I will keep an eyes on it. Still under warrenty and i have a second year service mid year.
 

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Could be a reaction to:
Climate control changing fan speed or air conditioning being toggled on and off
Other load such as using 12v socket and/or using socket in boot
Idle speed also governed by engine temp (electronic choke, if you will) but should settle when warmed up
Could also be affected my MAF I guess.
 

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Sounds like intermittent fault with engine temp sensor
 

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Discussion Starter #6
Could be a reaction to:
Climate control changing fan speed or air conditioning being toggled on and off
Other load such as using 12v socket and/or using socket in boot
Idle speed also governed by engine temp (electronic choke, if you will) but should settle when warmed up
Could also be affected my MAF I guess.
I did notice at the time if I had the AC on it seemed to be better. Why is this?
 

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I am getting the same with mine, seems intermittent and annoying! Car must have enough voltage in the battery because the S/S doesn't say its not working (even though its switched off). AC is switched off. Nothing is plugged in to the 12v socket. Climate is never on auto. And this is when the car has been driven and would be off choke. Mine is the 170 MA TCT, 15 plate with 8500 miles.
 

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Discussion Starter #8
I am getting the same with mine, seems intermittent and annoying! Car must have enough voltage in the battery because the S/S doesn't say its not working (even though its switched off). AC is switched off. Nothing is plugged in to the 12v socket. Climate is never on auto. And this is when the car has been driven and would be off choke. Mine is the 170 MA TCT, 15 plate with 8500 miles.
Went for a short drive yesterday and it was fine. May just be a dirty throttle sensor?? I had AC on but not on auto. Will ask about this issue when I have it serviced in a few months. I'm a low milage user, car is two year old 31 June and with only 9500k and serviced it should be running perfectly. Mine is a 170 MA TCT. My OLD Mito 135 TCT never did this:(
 

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I had the throttle body sensor cleaned!!!!! Didn't work and just wasted my time at dealers!!!!
Booker it back in and it was changed.....all is well again :)
 

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Discussion Starter #11
I had the throttle body sensor cleaned!!!!! Didn't work and just wasted my time at dealers!!!!
Booker it back in and it was changed.....all is well again :)
Will get them to check that when the service is due. Seems to be okay now but will keep an eye on it,
 

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Could be EGR valve too.

Quite a common issue on diesels that have done lots of town/city milage, or been used with degraded oil. This clogs up the EGR valve, either partially or completely stopping valve travel. Normally just remove, clean, refit & test does the job if this has occurred!
 

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I had egr issues with my previous Alfa , a 147 Q2 150 jtdm , despite its use being ideal for avoidance of it gunkin' up.
The new jtdm however has its egr close-coupled and I've never heard of it happening. I could be wrong but not sure if I've heard mention of issues here on Giulietta diesels.
 
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