turn up the boost to cure black smoke?

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Uncle Fes

Active Member
Posts
100
Location
Morocco
Hi

My Defender 200tdi chucks out buckets of thick black smoke under acceleration or full load. Back off and it stops.

I've fiddled with the fuel screw on the pump before and have ended up with no power, or misfiring, or white smoke... I'm a bit loath to touch the pump again! Especially as everything is dusty here.

I wondered if it would burn more diesel and smoke less if I increase the boost? Apparently easy to do by screwing the wastegate rod in, and it might go a little faster ;-)

Or am I barking up the wrong tree?
 
I'm sure you're right... It's got a new air cleaner, fuel filter etc. I've been told worn injectors might make it smoke.

We're a bit short of expertise here on adjusting pumps. New ones are expensive plus 100% duty, and if a vehicle runs no one worries about the smoke - part of the problem might be poor quality local diesel.

So I was just trying to think around the problem.
 
If it runs well i'd leave the turbo well alone, thats big money to repair/buy. I think there's a guide here somewhere on how to clean/recon injectors. If its poor diesel it may well be that but a general and cheap clean/repair of your fuel system is a good place to start. I'll see if i can find that guide...
 
You could always pop the top of the pump 4 screws and rotate the diaphragm clockwise for more fuel and anti clockwise for less, mark it first so you can return to standard setting if unhappy.
Takes two minutes.
If you google for pump adjustments you can find out exactly what does what on these pumps pretty simple.


Lynall
 
Funnily enough, 2nd hand turbos and new bearings etc aren't that expensive here. Yet another part of the problem is that the current turbo is a little small - I think it came off an old Renault!

I'm more worried about opening up the pump than anything... or blowing the head gasket.
 
Well, you're right in that the problem is fuel, but...

Black smoke is overfueling.

If you increase boost, you need to increase fuelling to take full advantage.

My logic is that as it's already over fuelling, raising the boost and introducing more air should help it burn more of the excess fuel.

I know it will put the turbo and engine under more stress, but then overfueling can kill head gaskets on it's own (I think).
 
But then you're just creating a situation where you're ignoring a problem by covering it up with another...if you're not careful you'll damage not only your turbo but your entire fuel system. Surely its best to leave the well functioning turbo alone and look at the reason for the unburnt/overfuelling?
 
Storm, I'm genuinely grateful for your advice... but I went ahead and tried it anyway!

These things are subjective, but I'm sure there is a reduction in smoke (not so much quantity as the fact that it's not so opaque), measured by the very scientific traffic light grand prix at night method...

It feels a little peppier, too.

I've ordered a boost gauge and when it turns up we'll see what the boost pressure is.
 
it doesnt hurt to increase boost by shortening actuator rod,there not near any limits as std,nearly all i know have them wound right up with no ill effects
 
I had a play with a 300 auto i had chipped and with wastgate locked up it got to 1.6 bar but it didnt seem to make any difference to the performance.
What you would get on std fueling i dont know.
I ran my TD5 disco at 22psi ish, again that was chipped, large cooler, boost controller etc.


Lynall
 
i always thought they smoked more when the boost was turned up anyway,mine blows out black smoke when ime climbing a hill and change gear,just thought it was normal .
 
Well, you're right in that the problem is fuel, but...

Black smoke is overfueling.

If you increase boost, you need to increase fuelling to take full advantage.

My logic is that as it's already over fuelling, raising the boost and introducing more air should help it burn more of the excess fuel.

I know it will put the turbo and engine under more stress, but then overfueling can kill head gaskets on it's own (I think).


But if you raise the boost pressure, that extra pressure goes down a wee black pipe to the diaphragm on the injection pump, shoves that down more, and the pump flings in even more diesel!

Take the advice offered ... back off the fuelling as described. It might need only a little less to make a lot less smoke.
 
sorry to but in on the topic,but think my boost was already turnd up before i got the landy,ita always smoked up hills as explained,should i do something about it,or leave it as is,
 
Charles, I had wondered whether the pump could sense the amount of boost pressure...
But then there are so many threads saying that just turning up the boost/fitting a big intercooler isn't enough - you need to fiddle with the pump to get more power.

My conclusion was the little pipe just tells the pump that the turbo is on boost; but I'm probably wrong.

After 300 miles today on very hilly four lane roads, climbing from sea level to over 1,500 feet several times, and cruising at 60-70mph, I'm sure there is less soot. We were 6 up, too - including the mother in law that's probably 6 and a half up.

It still smokes under power - but I had a new 200tdi Disco in '93 and that did too!

In terms of power, it now feels about equal to my (faint) memories of the Disco. I've probably just go it back to where it should be... Economy is better and it will pull up hiils in 5th that previously needed 4th.

I will try and change the injectors, which should help.

Overall, I'd say winding the boost up to cure smoke isn't advisable, but if you aren't a mechanical genius and aren't too fussed about loosing a 20 year old engine, it's worth a try.
 
Charles, I had wondered whether the pump could sense the amount of boost pressure...


My conclusion was the little pipe just tells the pump that the turbo is on boost; but I'm probably wrong.

The little pipe pushes the diaphragm down, and that progressively increases the MAXIMUM fuel delivery possible.

These things are prone to getting dirty, and then not working so well.

Even the wee pipe can choke up.

First makesure the wee pipe is clear, and is not cracked anywhere especially at the ends, and then think about taking the lid off the diaphragm chamber to see what state it is in.

If it needs cleaned out, do it. It must move down and up quite freely, but it may need a fair push.
 
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