Sluggish disco.........not any more!

That's the way, keep going a bit at a time and if you go too far and it smokes too much just back it off a bit.
The other Tweeks are well worth doing but try that one first it only takes minutes

Did the tweaks on the 200 fitted on my 110, and yet again it's a transformed vehicle. Completely eliminated the turbo lag I had, which was particularly noticeable in fourth when accelerating to motorway speed, but it now pulls like a train the whole time. Well chuffed

Well bugger me sideways, I had a bad flat spot when pulling away on my 300, I tweaked the centre screw only, just over a quarter turn and the flat spot has almost gone now, I'll give it a teensy bit more but I'm well impressed so far.

I think I'm right in my understanding that this screw does nothing once the turbo kicks in and the pressure lifts the diaphragm off the screw tip inside. It's all starting to make sense now

This thread should be made sticky

davek0974 said:

This thread should be made sticky

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Seconded

I have a 1998 R reg auto, is it possible to tweak the pump on this or not ?

Cheers

no unfortunatly not,

you will have the same one as me and the only thing we can do is have the chip inside reprogramed and its not just a plug in job,

as far as i am aware the pump has to be removed and the chip taken out of the pump, reprogramed and the the pump rebuilt and fitted back on the engine.

done my fuel pump today and makes a real difference. done all the changes in one go, screw under cap 1 turn, diaphram 1/4 turn and the large wheel 1 turn. cant see any smoke so i think i could go a little more but its realy good as it is:crazy_driver:

Some more research done over the weekend regarding the Bosch VE injection pump.

It appears the off-boost power screw and diaphragm position settings are related as they will both adjust the position of the fuel pin in relation to the boost cone.

The changes needed differ depending on the diagnosis found:

1-Low power off boost but ok when turbo kicks in - adjust screw only.

2-Ok off boost but low power when turbo kicks in - adjust diaphragm.

3-Low power off boost and low on boost - adjust both BUT adjust diaphragm first as it will also alter the off-boost setting.

4-On-boost power band is too late (high rpm) - adjust star wheel C/W and CC/W if it is too early.

Smoke and 'feel' are the diagnosis measures. A properly tuned diesel engine should 'just' emit black smoke at full/high power settings i.e. when you punt it a bit, they should never smoke all the time as this means wasted fuel as it is not being burnt. Note this is black sooty smoke only not grey etc. It should smoke when revved but then go clear as the engine settles again. 'Feel' is the tricky one as we all want more power but over egg the sponge and the MPG will go south and look out for burnt valves etc. His only reply to "What about the max fuel screw?" was "Dont go there, best left alone".

This was learnt over a couple of pints with a distant friend who spent some years working on these things when they were state-of-art stuff so back a while i guess But it does all seem to make sense so i have no worries about its validity. Its a simple pump by todays standards and very reliable, it popped up on quite a few vehicles.

amazing thread! With new info - how high we talkin regarding rpm of on-boost power? Mine was stupidly slow off-boost before alterin and didnt get full boost till 2-2500 rpm, does that sound normal? But i've now turned star by half turn, diaphram 100deg and torx by 1.5 turns, do get some dark grey smoke when i boot it, like foot to the floor. So im thinkin move diaphram back to standard position? Sorry for so many q's, any ideas appreciated

AFIK, and i'm no expert here by a long chalk The boost range on a D1 is around 1750rpm to 2850rpm where its maxed out but as i said, i aint no expert.

I turned my torx CW about 100 degrees or just over 1/4 turn and the difference is staggering, i had a very bad flat spot when pulling away - let the clutch up and she wanted to stall, never did but felt like it was going to. It was far worse with the trailer on. This one tweak has made a massive difference.

I'm leaving it there for a while now but i do think she could do with a little tweak on the diaphragm as she takes a while to gain speed or maintain speed on a hill, but its not terrible so i'm not too worried. She'll pull my 2400kg trailer at 55-60 in 5th all day provided shes not pushed to get there too fast

discomark88 said:

amazing thread! With new info - how high we talkin regarding rpm of on-boost power? Mine was stupidly slow off-boost before alterin and didnt get full boost till 2-2500 rpm, does that sound normal? But i've now turned star by half turn, diaphram 100deg and torx by 1.5 turns, do get some dark grey smoke when i boot it, like foot to the floor. So im thinkin move diaphram back to standard position? Sorry for so many q's, any ideas appreciated

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Mine gives a big puff of smoke when you boot it since the tweek but it's just gone through the mot so must be ok,what I would suggest is to back the smoke screw off a bit because adjusting the diaphram alters this so you might find that cures it. If not turn the diaphram back a bit till it stops the smoke. As long as the smoke is not exessive you should be fine.

Mwhaaa ha ha ha
Just done mine.
never wheel spun mine before lol

Cheers dave n jon. That range does sound about right, (its my second 200 n not as responsive as 1st) i now hit that dead on. Turn smoke scew back half turn n smoke colour is a nice pale grey now lol, but not massive amounts. May turn back more at MOT time to make sure. But for now i'll enjoy tacklin hills in 4th

Just gave the smoke screw a full turn in and what a difference on take off,so much more driveable

Good innit'

Makes so much difference

biolandy said:

Just gave the smoke screw a full turn in and what a difference on take off,so much more driveable

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Go on.................give it another half turn. You know you want to !

rollin danny said:

Go on.................give it another half turn. You know you want to !

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Ah but this is all off-boost power which is not used once she is rolling unless lugging her along at <1500rpm. Not much point in over doing this one, the big gain is in the diaphragm but if like mine it's not too bad when on boost, then I'm leaving that where it is at present.

Also, the more this screw is turned in, the later the turbo will be felt, they are both related, it will take more boost to start the diaphragm moving down and doing it's job.

davek0974 said:

Ah but this is all off-boost power which is not used once she is rolling unless lugging her along at <1500rpm. Not much point in over doing this one, the big gain is in the diaphragm but if like mine it's not too bad when on boost, then I'm leaving that where it is at present.

Also, the more this screw is turned in, the later the turbo will be felt, they are both related, it will take more boost to start the diaphragm moving down and doing it's job.

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not sure about the last part of this , (about the more boost part)
to be honest i dont think itl make any difference to the point the tubo will be felt whatsoever . you may however not feel the turbo surge as prominently because of the increased power pre boost so you dont get the turbo off turbo on feeling if you get what i mean

By screwing the torx inwards, it presses the diaphragm and spindle down against the spring harder. On the end of the spindle there is a cone about 10mm long. Now let's put the screw back to standard, imagine a graph plotting cone position against boost pressure, it would be a diagonal line graph(roughly) I.e as pressure rises, cone moves downwards by a relative amount, simplify, the cone is 10mm long and we have 10psi pressure, say the cone moves 1mm for each 1psi increase in boost. Now, we screw in the torx by 1mm, the cone is now where it would have been with 1psi boost but we are off boost, this is giving us the off-boost increase we wanted. But, we have now lost the effect of the first 1psi of boost and we now need 2psi to get the cone moving. In other words, instead of having 1-10psi of boost range, we now have 2-10psi of boost range I.e. a narrower band of boost, starting later.

This is why the two settings are connected, a simple option is to tweak the torx but a better option would be to do the diaphragm first then the screw together.

In the end it's the result that matters, and the benefit of tweaking that little scew is amazing, but I might put mine back later on and tweak the diaphragm and do it properly. Exhaust gas temperature is important though and when turning the power up, this should be checked carefully, unlike petrol engines which get hot when the mix is leaned out, oil burners get hotter with more fuel.

It's all good stuff

rollin danny said:

Go on.................give it another half turn. You know you want to !

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No I'm going steady,Danny don't want to bust anything on the old girl-might just up it a bit though