Belching black smoke and engine rattle

[brianwood]

Hi,
This one has me totally baffled.
The only codes thrown are egr faults.
Vehicle is a 2005 KJ diesel auto 200,000km
The problem occurs when driving if you decelerate to the point where the engine revs drop to idle, if you accelerate from there it blows black smoke, power is gone and if you really push it, the engine starts to rattle. You can overcome the problem by dabbing the throttle and going again - then its fine.
It has a new turbo, timing belt and I have just given the auto a service and replaced the oil pressure sensor and input speed sensor in the trans. MAP sensor is clean.
This problem has existed since owning the vehicle for the past 12 months.
I have also removed the throttle butterfly, as I wasn't sure whether this was sticking. Surely someone else has experienced this???
I'm totally clueless....

[oldon]

Sounds like over fuelling, the rattle is really excessive fuel being squirted in. I'd have thought with all the electronics of today, the ecu would pull some fuel & timing out to prevent this. Has it been reprogrammed or chipped? If egr is dirty, clogged or not working, there could be some carbon on piston combustion chamber that gets hot enough to light the fire a bit early. Best block that egr anyway, you don't want dirty exhaust going through the inlet. Timing belt, you sure it's timed correctly, fuel in too early will make diesel rattle. When you lift off then boot it again, you've given it a chance to clear excess fuel. Regards oldon.

[Macca2801]

Stuck or sticking egr will do this.

[glend]

Turbo vanes could be sticking.
New turbo when and who did the job, is it a proper Garret turbo or a remand unit?
BTW there is no throttle butter fly on this engine, there is a flow control valve but its primary function is egr gas mixing via creation of a flow vacuum that aids exhaust suction - and it closes on shutdown.

2005's seem to have more egr problems than later models and thus might be due to it hwving an electrical egr valve where later years are vacum actutated.

[brianwood]

Thanks guys.
I put the Chinese turbo in. Problem existed prior to turbo replacement too. Would I possibly get an under boost code if vanes were sticking?
As for Oldon's comments re timing, the problem is intermittent, so timing could not be an issue.
At this stage, it looks like everyone's comments re EGR could be on the money. I'll find a way to blank off the EGR. That's what the codes indicate too.
Thanks everyone.

[Macca2801]

EGR solenoids are renowned for sticking open and bleeding exhaust gas into the chamber and diluting your oxygen content..hence the black smoke from over fueling. Blanking is off is beneficial due to reducing the carbon and soot intake into the manifolds and engine for the long term but I would just remove and clean the valve to ensure that is the problem. At least that way you ensure you are on the right tack.

Goodluck
Matt.

[brianwood]

Thanks Matt. Yeah I'll have a good look at everything when I pull it off. I'll clean it up and work out how to blank it off. Blanking should always be done when near new to save all this grief IMHO.