Jerking when setting off (1 Viewer)

Nov 15, 2007
241
260
Nottinghamshire, UK
Funster No
849
MH
A Class
Exp
20+ but 30+ as a tugger
When we pull away from lights or junction the camper jerks quite badly until we get going. It feels like the accelerator return spring (if there is one) is missing. Also when idling the engine RPM starts to creep up from 750 to 1500. All the local Fiat dealers are fully booked next week and we leave for France at the end of next week. The engine is the Fiat 3.0 ltr and its a 2009 model any suggestions would be very helpful
 

irnbru

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Our AT does that too when engine is cold

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Techno

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I've never experienced that with my 3 litre and the rpm is 800 at tick over whether hot or cold
 
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Vennwood
Nov 15, 2007
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260
Nottinghamshire, UK
Funster No
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It was fine until a couple of days ago and while we haven't owned it long it has been fine. Full service history. Just a B***er this is happening just before we set off.

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Techno

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And you haven't got a check engine warning?
IMHO it sounds as though the throttle valve is not closing fully.
 

Judge Mental

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do you really need a Fiat garage to diagnosis this..look around locally for recommended commercial garage..
 

Techno

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do you really need a Fiat garage to diagnosis this..look around locally for recommended commercial garage..
Peugeot or Citroen garage will do the same job. EDIT or even IVECO seeing as it is their engine

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Judge Mental

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Peugeot or Citroen garage will do the same job. EDIT or even IVECO seeing as it is their engine

I just googled and there are loads including Iveco which would be my first call if Fiat/Peugeot/ Citroen busy. would try and find someone good outside the expensive franchised set ups..loads of reputable mechanics around.
 

DBK

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The jerking might be engine mounts and the tickover issue unrelated. Not sure that help!

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Mousy

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I seriously misread the title to this thread.

I thought "setting" read " getting"

:D

Great minds think alike! I almost choked on my mouthful of spaghetti Bol.
Opened the thread in great excitement only to find technical questions like manual or auto:eek::rofl:

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Vennwood
Nov 15, 2007
241
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Nottinghamshire, UK
Funster No
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MH
A Class
Exp
20+ but 30+ as a tugger
I thought that only a Fiat dealer would have the "magic box" that would connect and instantly tell you what the problem was.

To go back to something Andy mentioned. I did have an amber engine warning light on when I picked up the camper but the dealer said it was "due to the engine battery going flat while it stood on the forecourt and that had been reset" To be fair I haven't had the problem since.
 
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Vennwood
Nov 15, 2007
241
260
Nottinghamshire, UK
Funster No
849
MH
A Class
Exp
20+ but 30+ as a tugger
Not sure about the jerking on take off but the idle speed issue could be down to a faulty alternator.

D.

Thanks Dave,

I'll bear that in mind if I can get it booked in and mention it. What would cause that? - The camper has a B2B fitted and looking through the previous owners service history this vehicle has a history of "flat engine battery" The selling dealer had to "clear the fault log as there were 7 instances of low engine battery" Again looking through the records it has had 2 replacement engine batteries in the past 5 years - odd don't you think?
 

Judge Mental

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Yes...points to wot Dave said:)

Any auto electrician could varify.....

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Vennwood
Nov 15, 2007
241
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Nottinghamshire, UK
Funster No
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20+ but 30+ as a tugger
Yes...points to wot Dave said:)

Any auto electrician could varify.....

You would think so but the records show it has been into several Fiat dealers and Hymer dealers with this problem but none have identified the problem as a faulty alternator. I'm thinking that Dave may have hit on something the others have missed.
 

dave newell

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It is feasible that the B2B is causing the revs rising issue. The alternator output is regulated via the engine ECU, if it sees a lower than expected voltage at the alternator output it will increase rpm to compensate. The B2B works by fooling the alternator to produce more current, it does this by artificially putting more load on the alternator. If the engine battery is lowish, say 50% charged, then the additional load of the B2B may just cause the voltage at the alternator output to be lower than the ECU wants to see so it raises the rpm. Try removing the B2B fuse from the engine battery to rule it out.

D.
 
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Vennwood
Nov 15, 2007
241
260
Nottinghamshire, UK
Funster No
849
MH
A Class
Exp
20+ but 30+ as a tugger
It is feasible that the B2B is causing the revs rising issue. The alternator output is regulated via the engine ECU, if it sees a lower than expected voltage at the alternator output it will increase rpm to compensate. The B2B works by fooling the alternator to produce more current, it does this by artificially putting more load on the alternator. If the engine battery is lowish, say 50% charged, then the additional load of the B2B may just cause the voltage at the alternator output to be lower than the ECU wants to see so it raises the rpm. Try removing the B2B fuse from the engine battery to rule it out.

D.

Thanks for that Dave, I'll try that in the morning. I don't have a lot of faith in the control panel reading however it does say the engine battery voltage is 12.6 which I thought wasn't too bad. I had the EHU connected last week so it should have been fairly well up. I did notice that one of the leisure battery terminals was very loose when I was looking around earlier so tightened it up. Don't supose that could cause a problem?

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Last edited:

PP Bear

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I seriously misread the title to this thread.

I thought "setting" read " getting"

:D

Great minds think alike! I almost choked on my mouthful of spaghetti Bol.
Opened the thread in great excitement only to find technical questions like manual or auto:eek::rofl:

I'm with you guys, was shaking with anticipation :rofl:

On a serious note, I hope it gets sorted ASAP :crying:
 
Feb 24, 2013
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I do wish you well, being hopefully through some electronic 'woes' of my own

Too clever for their own good these days I reckon, too many sensors IMO (y)
 
Aug 6, 2013
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I don't know whether it's a fly-by-wire accelerator pedal - but if so I'd suspect a failing pedal pot.

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TerryL

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Mar 5, 2010
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I had an alternator fail and the first thing I noticed (after the warning light of course) was an increase in revs. If it's an intermittent fault, as Dave says, could it not also be leading to the "jerky" problem? As DavidG58 says, sometimes these electrickery tyhingies are too clever for their own good.
 
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OP
Vennwood
Nov 15, 2007
241
260
Nottinghamshire, UK
Funster No
849
MH
A Class
Exp
20+ but 30+ as a tugger
It is feasible that the B2B is causing the revs rising issue. The alternator output is regulated via the engine ECU, if it sees a lower than expected voltage at the alternator output it will increase rpm to compensate. The B2B works by fooling the alternator to produce more current, it does this by artificially putting more load on the alternator. If the engine battery is lowish, say 50% charged, then the additional load of the B2B may just cause the voltage at the alternator output to be lower than the ECU wants to see so it raises the rpm. Try removing the B2B fuse from the engine battery to rule it out.

D.

First of all I connected the EHU last night and left the batteries on charge all night and they are all reading over 13 volts, settling back to 12.7, 12.8 volts. This morning I took the fuse out and started up. Idle RPM fine. I put the fuse back in, started up and idle RPM - fine. So it could be as Dave says and the engine battery was low and the RPM rise was to compensate. I'll let it settle for a day or two and try again. In the meantime I'm trying to find a dealer in the area that can check out the jerking.
 

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