V50 Engine 2.0D : A rough cold idle - tried it all

[Jenandgaz]

Hi all. We have a 2005 V50 2.0l diesel. I have searched the forum high and low, tried everything suggested but still no joy.

Upon a cold start the car idles really roughly (rocks the car a bit) until warm, puffing some white smoke.

I have replaced the glow plugs.
I have replaced the whole throttle body including sensors.
I have fitted a egr valve plate.
I have checked all pipes and connections (replaced a leak off pipe and fitting)

It sometimes has the rough idle (not as bad) even when warm but accelerates smoothly and pulls very well with no hesitation.

Any help would be appreciated before I have to get expensive advise.
Thanks!

[AndyV7o]

When you say throttle body, do you mean fuel rail? Diesels dont have a throttle body, so a bit of clarification here might help...
Also, it could be an engine mount or some mounts, fuel filter, air entering fuel system on suction side, you say you've checked lines and connectors but I would imagine that would be for a positive leak, i.e. fuel coming out, but you can get air being sucked in instead, can often be exacerbated by a blocked fuel filter causing resistance to flow etc.
It might even be sticky piston rings, if its been run right to the extreme of extended service intervals, esp if lower quality oil used, you can get a build-up of crap in the ring grooves which causes them to stick lowering compression. If its been done every 12k or less with big brand oil this is much less likely to be the cause.

[Jenandgaz]

"When you say throttle body, do you mean fuel rail? Diesels dont have a throttle body, so a bit of clarification here might help..."

In the pic the bottom red circle. This whole unit has been replaced. I have read that some times it gums up so I changed everything including sensors.

As for mounts I don't see how that could be the issue as it sounds rough too like its missing on a cylinder.

Also if sucking air in surely it would continue to suck air in, not stop after 5 or 10 minutes.

I have read white smoke indicates unburnt fuel.

Thanks for taking the time to respond

[marccowley]

You could have a head gasket on the way out? Does it use any water? Or a dodgy injector. Have you done an injector leakback rest?

[Jenandgaz]

Originally Posted by marccowley

You could have a head gasket on the way out? Does it use any water? Or a dodgy injector. Have you done an injector leakback rest?

Doesn't use water. I do not know how to do a leak back test but will look into it
Thanks

[AndyV7o]

If its taking air into fuel lines, it can run better when hot, nowt related to time in particular.
Engine mounts are indeed less likely as it goes away when hot, but if one has collapsed or engine is touching somewhere, it can transfer vibrations which can feel like a rough idle, that are normally isolated by the mount. The stuff in red is induction/egr related stuff.
Since it isnt the fuel rail that has been done, the next likely item is the fuel pressure regulator on either the end if fuel rail, or on high pressure pump, this is a common cause of rough idle if faulty. Again, things can behave very different when hot or cold. Sometimes temp is a key factor, sometimes it causes or disguises a problem.

When you replaced leak-off pipe, did you do a leak-back test? You may have a faulty injector, and a leakback test usually will indicate if so with either excessive leakback or none at all.

[andy_d]

Originally Posted by Jenandgaz

Hi all. We have a 2005 V50 2.0l diesel. I have searched the forum high and low, tried everything suggested but still no joy.

Upon a cold start the car idles really roughly (rocks the car a bit) until warm, puffing some white smoke.

I have replaced the glow plugs.
I have replaced the whole throttle body including sensors.
I have fitted a egr valve plate.
I have checked all pipes and connections (replaced a leak off pipe and fitting)

It sometimes has the rough idle (not as bad) even when warm but accelerates smoothly and pulls very well with no hesitation.

Any help would be appreciated before I have to get expensive advise.
Thanks!

have you tried getting a Proper Diagnostic read out from vida/dice setup?
if not start there it will show any faults , rather than swapping parts and hoping

[hoks]

Originally Posted by Jenandgaz

Hi all. We have a 2005 V50 2.0l diesel. I have searched the forum high and low, tried everything suggested but still no joy.

Upon a cold start the car idles really roughly (rocks the car a bit) until warm, puffing some white smoke.

I have replaced the glow plugs.
I have replaced the whole throttle body including sensors.
I have fitted a egr valve plate.
I have checked all pipes and connections (replaced a leak off pipe and fitting)

It sometimes has the rough idle (not as bad) even when warm but accelerates smoothly and pulls very well with no hesitation.

Any help would be appreciated before I have to get expensive advise.
Thanks!

Is it sililar to one in the video below?

https://youtu.be/71ERwjIHTTw

I have this issue, rough cold start.... The colder it gets and and longer it sits the worse it gets. After being parked for 16 hours in similar weather I had to crank it 6 times to get it running.

[Montana]

as above, get the codes read properly by VIDA/DICE before spending anymore monies.

[FunkyMelon]

It sounds to me like the head gasket is on it's way out.

You only need it to leak a tiny big of coolant into the liners for a misfire to happen, then as it burns off it'll run fine again.

Had this on my old car, same symptoms sadly. Get a hydrocarbon test done, it'll confirm if any exhaust gasses are in the coolant - Shouldn't cost much at all and will confirm at least.