D24TIC Large build up of soot in exhaust

[Laney760]

I noticed this morning that there's a large build up of soot in the tail pipe of my exhaust. The car doesn't smoke, it's fairly low mileage and is in fine fettle. Does the soot being there indicate that there will be a large build up of soot in the system and in the intake manifold or is this pretty standard in the exhaust, although I've never noticed it in other diesels? Is it a sign of my hard driving? I know in my last D24Tic that the egr had been blanked off, I'm pretty sure I checked that it has been in this one too but I need to check again. I've just been reading about cleaning the intake manifold and system off of the car, is this something that's advisable for a novice like myself if the car needs it or am I advised to have a (reputable) garage do this? Thanks

[Laney760]

What I should of made clearer is that this is not a normal sooty exhaust, theres a big mound of the stuff in the tailpipe

[jamesferns]

Hi laney, have you been doing a lot of slow/stop start driving? maybe it just needs a italian tune up

[Palmer]

Give it a good boot to clear any crap out haha :-D

i disabled my egr for the prevention of a soot, oily build up through the intake tract.

[peter burton]

my 940 diesel also thick black layer.does get max revs blow out and odd long run.egr blanked off.oil catch tank in line from breather to turbo.been putting a gallon of parafin in tank on last two fill ups this has remarkably cleaned up injectors and cut smoke from exhaust.now on 187000 miles.clutch biting point very low and cam belt coming up for replacement.i wonder if cleaning out intercooler and intake big job.

[Laney760]

The car does get regular clear outs on the motorway

It is pre-cat

I'm wondering if this has been building up since the car had the pump tuned up about 35 thou ago? The car returns very poor mpg due to this tune up by the previous owner although it does perform well. As well as the soot layered around the pipe, there was actually a big pile of it which was almost obstructing the flow from the exhaust, I have in effect swept it out

If they run very rich when tuned up I'm wondering what this tune up is doing to the engine in general

I havent run it on veg oil for a while, wondering if that is what was clearing it out once in a while?

Lots of wondering!

[TiredGeek]

If someone has messed around with the pump that's the problem! It's simply running way too rich in some poor attempt to get more performance and you're dumping loads of unburnt fuel out through the tail pipe.
Get that sorted and you might lose a tiny bit of performance but you'll get much better mpg....

[Laney760]

Originally Posted by TiredGeek

If someone has messed around with the pump that's the problem! It's simply running way too rich in some poor attempt to get more performance and you're dumping loads of unburnt fuel out through the tail pipe.
Get that sorted and you might lose a tiny bit of performance but you'll get much better mpg....

The pump was tuned by professionals when brand new. I know I have to choose between economy and performance, I will lost quite a bit of performance but I've been thinking today that I am going to put it in the diesel specialists and have it detuned, diesel is getting very pricey to be getting so little mpg and it is obviously very polluting in this state and I'm still none the wiser if other parts of the engine are coked up

[TiredGeek]

A diesel engine pulls in far more air than is required for combustion, all these people do is turn up the fueling to inject more fuel and therefore give more power.
If done right it's fine, if they get the ratio correct then you're using all the available oxygen to burn the fuel, it sounds to me very much like they've gone overboard and you're using all the air up and still having unburnt diesel left. This is very sooty.
Idealy you need to burn 100% of the fuel and use 100% of the available oxygen in the cylinder. From the factory (AFAIK) the ratio can be more like 100% fuel and only 60% of the oxygen is needed to burn it. I think your's is the other way around, 90% of the fuel burnt before you've run out of oxygen.....

Unless of course you've got a duff injector or two......

[Laney760]

Thanks all. The pump was tuned up about 5 years ago, nigh on 40,000 miles ago and has been fine until now. Pretty sure my injectors are all good. I'll run it into my local diesel specialists I think, get them to give it a once over, won't hurt....