Running Rough Even After Warm

[Jamie1]

First post here and looking for some advice.

I have a 2005 120d which runs lumpy even when warm, it's not bad above 2000 revs but when ticking over it feels like not all cylinders are firing.

I have had a diagnostic test done and all the glow plugs have failed but no injector faults were noted, will changing them resolve this, I thought if that was the problem it would give starting difficulties not rough running when warm.

Any help would be really appreciated.

Cheers

Jamie

[Guest DazH]

Engine will start fine with all plugs failed (Although this is unusual to hear all have failed as far as im aware)

If you hadn't of ran a scan on the ECU, I would of said some kind of sensor was shot causing it to under/over fuel. When you get the glow-plugs looked at, a visual inspection of the injection system is what I recommend.

Keep us posted mate

Daz

[Jamie1]

Thanks for that Daz.

it does feel like a fuel problem to me, it did get a bit better when I pumped in a load of redex in but that's not going to solve it.

What would be the most probable cause if it's a fuel issue + or - what it needs.

Cheers

Jamie

[Guest jeffthro]

Don't like to disagree with fellow members, but if ALL the glow plugs are shot, I can't believe she'll even think about starting. I had a Pug 406 TDi, and if even one glow plug went down she'd take ages to fire up. That is, after all, the main reason they are there. I can't help wondering if the diagnostic check was right? If they are definitely knacked, then obviously they do need replacing, I'd be inclined to do that first before spending any more money on other things?

[Jamie1]

It starts ok but really rough, tractor rough !!, I have changed the fuel filter with no change, prolonged temperatures below zero might change it starting but thankfully not put to the test..

All glow plugs failing sounds uncommon by what I have read, it is going back in for a further test so until then please keep the comments coming so hopefully I don't shell out for parts that I don't need, most garages don't seem to understand what the diagnostics are telling them is this common.

Cheers

[Guest jeffthro]

I think you're right to go back in, maybe even a different garage for a second opinion on the diagnostic test. If she's starting more or less "on the button", I really don't think its going to be the glow plugs.

[Guest Mister Dabsy]

Have you changed the fuel filter recently? If yes then there maybe air in the system.

If she still runs like a bag of marbles when up to temp then it won't be the glow plugs causing it.

In my opinion you would need at least half of the glow plugs to be working to start a diesel, unless it is a warmish day !!

[Jamie1]

I had the fuel filter changed as the first go at a fix, it helped a bit but not the solution, it has never not started even at -6 over a few nights, as stated its like firing up a Leland tractor but it starts.

Cheers and thanks for taking the time.

Jamie

[Guest Mister Dabsy]

Injector failure or pump-seal then... Just a thought !

(waiting in anticipation for the village idiot to suggest coil-pack !!)

[Guest DazH]

Don't like to disagree with fellow members, but if ALL the glow plugs are shot, I can't believe she'll even think about starting. I had a Pug 406 TDi, and if even one glow plug went down she'd take ages to fire up. That is, after all, the main reason they are there. I can't help wondering if the diagnostic check was right? If they are definitely knacked, then obviously they do need replacing, I'd be inclined to do that first before spending any more money on other things?

It'll start. Warm day and it'l start. It isn't theoretical, I've done it. Glow plugs are to assist a cold-start. Take the cold out the equation and it only becomes assist.