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[prj]

I have a problem with rough idle when warm on my Omega.
There are no fault codes stored in the ECU.

The rough idle is best characterized as a strong vibration. It does not hunt at all, there is just strong vibration throughout the car and the engine shakes. Quite sure there is a mechanical problem with the fuel distribution from the pump to one or more cylinders.
Before someone says "that's how diesels work" - no, it used to be fine before

Rising the RPM even a tiny bit the problem goes away almost completely, but there is still a feeling that one cylinder is not running quite right.
So it must be an issue with very low injection quantities, as the engine works perfectly when driving.

I am going to take off all the nozzles on Monday and get them checked on a bench, as well as do a compression test, but perhaps someone has experience/cure they can share about this problem.

[Seth]

Experienced this fault a few years ago.

Turned out to be that the fuel filter wasn't seated correctly to the heater boss. (Previous owner).

[prj]

Okay, thank you.
I will get the entire fuel delivery checked out.

It would be actually quite logical, if it is drawing in air from somewhere, that it runs bad.
I do have a slight diesel leak around one of the nozzles though, so I think it could be that one as well.

[Agemo]

Are you sure the injector is leaking? It could just be a leak-off pipe. Well worth checking them all before compression test etc. 

[hoofing it]

I have a problem with rough idle when warm on my Omega.
There are no fault codes stored in the ECU.

The rough idle is best characterized as a strong vibration. It does not hunt at all, there is just strong vibration throughout the car and the engine shakes. Quite sure there is a mechanical problem with the fuel distribution from the pump to one or more cylinders.
Before someone says "that's how diesels work" - no, it used to be fine before

Rising the RPM even a tiny bit the problem goes away almost completely, but there is still a feeling that one cylinder is not running quite right.
So it must be an issue with very low injection quantities, as the engine works perfectly when driving.

I am going to take off all the nozzles on Monday and get them checked on a bench, as well as do a compression test, but perhaps someone has experience/cure they can share about this problem.

You need a special  machine to test diesel injectors to see what preasure they crack at this is best done by a specialist diesel company.
I'd be starting with the leak off pipes/fuel filter housing also try putting forte diesel treatment directly into the fuel filter this will help clean out the injectors

[jonnyboyws6]

Mine did this. I changed the filter, the leak off pipes, the lift pump, blanked off the egr valve, had the injectors checked and cleaned, and probably lots of other stuff that I can't remember now. Consensus of various people was it must be the pump, but I never did get to the bottom of it. Then I started doing a lot of miles in it, and one day it magicked itself better. Then it blew up.

Sorry for the unhelpful post. Have heard of similar problems with a couple of BMs too. Hope someone more useful than me comes along soon!

[prj]

All the injectors have been rebuilt now.

I am thinking it's either the engine mounts or incorrect timing (and my tool can not for some reason display the measuring blocks on this engine, disconnects right away).

[Omegatoy]

DMF gone if manual

[Goldy]

Been there done that,think you will find it's one or both engine mountings.Offside takes most hammer,they're VERY expencive for a piece of rubber with some oil in.

[prj]

What I have done so far:
1. Rebuilt and calibrated all the nozzles.
2. Replaced the lift pump and the fuel filter.
3. Replaced the engine mounts.
4. It is an autobox car, so no DMF here, just the torque converter.

The vibration definitely comes from the engine, and if I go even a little bit above idle it disappears.
The entire exhaust vibrates quite heavily - I wonder if there is supposed to be a flexi on it to reduce vibration. I am going to look at it, and have one fitted if there is none.

I will play with the static injection timing a little, it might be set too early, that will cause a vibration as well, especially at very low revs, but as you give it a bit more, the timing naturally needs to be a bit more advanced and the problem would go away.

[prj]

Checked timing, 2.5 requested, 2.4-2.6 actual on idle, all is well.
Replaced all the "holders" for the exhaust, no change.

If you put your hand against the car, you can feel no vibration at the front, but as you move back there is more and more vibration.
The problem is definitely the exhaust going into some sort of oscillation. The engine is not really vibrating out of ordinary.

Having flexi fitted today, hoping it'll fix it.

[prj]

Flexi sorted 90% of the problem.
There is a very light vibration still, felt through the steering, but this is an old school diesel, and I don't think it is out of the ordinary.
If I want it fully vibration free, I think the only thing that will fix that is a new injection pump, but the old one still works just fine and car goes very well after tinkering with the ECU and upping the boost to 1.25 bar

But really, now the vibration is like any other diesel.

The main issues were:
1. Lack of flexi on the exhaust and exhaust going into a resonance.
2. Worn out engine mounts.
3. Worn exhaust mounts.

Flexi made the biggest difference. The exhaust has been repaired and welded on in the past, that might also be a contributing factor.

[Omegatoy]

Had similar before,guy was compaining of exhaust resonance on a td,when inspecting it it only happened when engine was hot,turned out to be,where exhaust goes over brace bar by gearbox,when exhaust hot it was just touching and vibrating or resonating,went through the whole car and sounded awful, i simply unbolted the joint at front joint and the nest one along,loads of oil and freeing agent got it to turn in the joints just enuogh to clear the bar,noise/resonance etc was gone!!