V50 Engine 2.0D : - Intermittent rough idle

MartinKarafin · Nov 15th, 2017, 19:09

I have a 2005 Volvo V50 2.0D that I'm having trouble with. The car starts very well but from time to time it idles rough and there are noticeable surges in rpm (fluctuations of 50 to 100 rpm). It gets better within a few minutes of running.

What I know:
*The rough idle occurs at random (Runs great when it doesn't happen)
*When its running rough, it also smokes and smells of unburnt diesel.
*It isn't losing any coolant or oil
*The return fuel flow from the injectors is practically identical
*There is air in the fuel lines (Visible through the clear line)
*The car pulls very well and has lots of power

What I've tried:
*Replaced all the filters
*Replaced the timing belt
*Cleaned the throttle body and tried chamfering the edges of the flap (It is possible that I wasn't aggressive enough)
*Replaced the fuel filter housing (Didn't help, air is entering the system before the filter)
*Visually checked the vacuum lines and they seemed to intact

What could be causing this sort of behaviour? Could it simply be a flaky sensor? I've also thought about the fuel pressure and volume regulators.

The Thong · Nov 16th, 2017, 13:59

Have you have the codes read in Vida?

MartinKarafin · Nov 16th, 2017, 16:07

Quote:

Originally Posted by The Thong

Have you have the codes read in Vida?

I have and there are no fault codes related to the engine.

The Thong · Nov 16th, 2017, 18:55

You can get air bubbles in the fuel lines, mine did. DPF?

MartinKarafin · Nov 16th, 2017, 19:30

Quote:

Originally Posted by The Thong

You can get air bubbles in the fuel lines, mine did. DPF?

No DPF. There are indeed air bubbles in the fuel lines. Could air in the fuel system cause it to run like this? It seems unlikely that that could cause it to run rough one day and fine the next.

The Thong · Nov 17th, 2017, 08:51

It never caused any issues on my motor but if the filters not fitted right it can so I hear. I was never comfortable with having bubbles in the fuel system but apparently it’s not unusual. Are we talking lots of bubbles?

The Thong · Nov 17th, 2017, 08:56

I will add, my V50 used to have a slightly lumpy tickover sometimes but that was intermittent so I didn’t worry about it. Anyway, good luck with your investigation

TT

Nov 15th, 2017, 19:09	#1
MartinKarafin New Member Last Online: Nov 12th, 2023 11:22 Join Date: Nov 2017 Location: Narva-Jõesuu	Intermittent rough idle I have a 2005 Volvo V50 2.0D that I'm having trouble with. The car starts very well but from time to time it idles rough and there are noticeable surges in rpm (fluctuations of 50 to 100 rpm). It gets better within a few minutes of running. What I know: The rough idle occurs at random (Runs great when it doesn't happen) When its running rough, it also smokes and smells of unburnt diesel. It isn't losing any coolant or oil The return fuel flow from the injectors is practically identical There is air in the fuel lines (Visible through the clear line) The car pulls very well and has lots of power What I've tried: Replaced all the filters Replaced the timing belt Cleaned the throttle body and tried chamfering the edges of the flap (It is possible that I wasn't aggressive enough) Replaced the fuel filter housing (Didn't help, air is entering the system before the filter) *Visually checked the vacuum lines and they seemed to intact What could be causing this sort of behaviour? Could it simply be a flaky sensor? I've also thought about the fuel pressure and volume regulators.

Nov 16th, 2017, 13:59	#2
The Thong VOC Member Last Online: Today 20:59 Join Date: Jun 2012 Location: The Independent Republic of Leamington Spa	Have you have the codes read in Vida? __________________ Never underestimate the power of stupid. It’ can’t be reasoned or negotiated with and you’ll never never beat it…. Cut your losses, smile and walk away Currently Volvoless but Thong will be back

Nov 16th, 2017, 18:55	#4
The Thong VOC Member Last Online: Today 20:59 Join Date: Jun 2012 Location: The Independent Republic of Leamington Spa	You can get air bubbles in the fuel lines, mine did. DPF? __________________ Never underestimate the power of stupid. It’ can’t be reasoned or negotiated with and you’ll never never beat it…. Cut your losses, smile and walk away Currently Volvoless but Thong will be back

Nov 17th, 2017, 08:51	#6
The Thong VOC Member Last Online: Today 20:59 Join Date: Jun 2012 Location: The Independent Republic of Leamington Spa	It never caused any issues on my motor but if the filters not fitted right it can so I hear. I was never comfortable with having bubbles in the fuel system but apparently it’s not unusual. Are we talking lots of bubbles? __________________ Never underestimate the power of stupid. It’ can’t be reasoned or negotiated with and you’ll never never beat it…. Cut your losses, smile and walk away Currently Volvoless but Thong will be back

Nov 17th, 2017, 08:56	#7
The Thong VOC Member Last Online: Today 20:59 Join Date: Jun 2012 Location: The Independent Republic of Leamington Spa	I will add, my V50 used to have a slightly lumpy tickover sometimes but that was intermittent so I didn’t worry about it. Anyway, good luck with your investigation TT __________________ Never underestimate the power of stupid. It’ can’t be reasoned or negotiated with and you’ll never never beat it…. Cut your losses, smile and walk away Currently Volvoless but Thong will be back

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