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#Post#: 16513--------------------------------------------------
Turn up your Tdi
DIR By: Glen
Date: March 21, 2012, 6:26 pm
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Actully no, don't, it drives like shit!
My Tdi has always been incredably noisy and unrefined.
Compaired to my 2.25D its really quite rough, though that is
quite a smooth 2.25D and this probubly has the shortest streight
pipe exhaust possable (pick the shortest route from a disco 200
positioned turbo to just behind the front tyre and thats what it
is in 60mm pipe). Its rather sooty when your getting a move on,
also rather eager to accelerate and surprisingly rapid though
that doesn't help its tendency to be tail happy, especally
(though not exclusively) if its been raining.
I have no idea when it got fittled with, just that it has. The
LDA tamper cap shows signs of being prised out in the past, and
though the lock collar on the max fueling screw is still there
you you can get more than enough tweeking out of them with it
still in place for it to be meaningless. Maybe it was still in
its original 'packaging' or maybe the person who converted it
though a S3 gearbox would love the extra power, who knows.
Basicly ever since LRO explained what screw to turn on a Bosch
VE pump no second hand Tdi can be assumed to be in any state of
tune.
I've been thinking about turning it down for the last couple of
months, but the fun of overtaking up hills (really really
easily!) just kept getting the better of me.
Finally backed the party screw off 1/2 a turn and wow, its a
completely different engine to drive! The exhaust doesn't snarl
quite so much (though even without a silencer I still think they
sound nicer with a longer pipe), much reduiced diesel clatter in
the cab, even when idleing at any speed (ie no load), less
fluttery for a given pedal position (its on an accelerator cable
but this would have a massive effect if it was on a rod, which
it used to be (that didn't last long as it was unbearable!)), I
really wish I'd done it sooner! If you think your donor engine
has been tweeked, its definately nicer backed off a bit.
I havn't bothered reajusting the LDA so it still smokes a bit
before the boost picks up, might be a worry on a vehicle young
enough for a smoke test but it should be fine for the MOT as is
so I can live with that - its only an issue if you labour it in
a gearbox unfriendly way anyway. Max boost seems to have
dropped slightly from the factory corect 0.8 bar it was before
(almost certainly waistgate limited so not a good indication of
how tuned it was, nice to know the waistgate is working though,
someone obveously didn't fiddle with that bit) to maybe
0.6...0.7 bar so perhaps its now turned a tad below stock and
not getting quite enough fuel to open the waistgate now but it
still pulls well enough and it'll only be kinder on the
drivetrain.
It'll be interesting to see if it manages to exceed 30mpg now as
its always been rather disapointing on that front, struggleing
to exceed 26mpg back when it was on 4.7:1 diffs. In theory I've
always thought turning the pump up shouldn't nesiserally make a
significant difference to overall fuel consumption as you only
use the extra fuel during acceleration (thus its only worse if
you floor it, though to be honest when I need to accelerate I
genrally ask it to get on with it, the habit of having a 2.25D
(which is good on fuel by the way)) so if you keep the rate of
acceleration the same it shouldn't make a difference. That
slightly fluttery nature of it though probubly means rather than
properly holding a steady speed like the chilled more factory
setting, the overtuned edgyness is constantly doing tiny
acceleration/decelerations instead which will equal the same
rotational speed but less efficently - lets see, same rules as
before, don't exceed 60mph but try get upto 50 where ever
possable and conserve momentum (the same driving style gets
27...30mpg from my 2.25D so it can't be that bad).
#Post#: 16519--------------------------------------------------
Re: Turn up your Tdi
DIR By: Luke
Date: March 21, 2012, 7:11 pm
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I've been thinking for a while about turning the Tdi down in the
lightweight, I haven't turned it up but It's a right nasty
bastard! It's bloody quick but it's quite loud and not nice at
all with the rod accelerator linkages!
I may do it sooner having just read that ^^^
#Post#: 16527--------------------------------------------------
Re: Turn up your Tdi
DIR By: The_Resurrection
Date: March 22, 2012, 2:38 am
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It is worth marking the standard position before doing any mods.
#Post#: 16891--------------------------------------------------
Re: Turn up your Tdi
DIR By: NiteMare
Date: March 24, 2012, 6:50 pm
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my bitsa has only had the diaphragm and pin turned through 90*,
minimal smoke at any time and can only really be seen as as
screen at night in following headlights if i get lead footed
i think Big Ears pump has been tweaked but i've also fitted a
300 turbo/manifold he seems to chuck out a bit more smoke
#Post#: 17023--------------------------------------------------
Re: Turn up your Tdi
DIR By: estwdjhn
Date: March 25, 2012, 4:16 pm
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I think it varies from engine to engine - I had one turned up to
the n'th degree, went like a scaled cat, ran sweet as anything,
only smoked while being floored off-boost (I'd run out of
adjustment on the off boost smoke control screw).
The current one I've just turned the diaphram 80 degs (smoked
like a pig at 90 deg), and it doesn't go a great deal better,
but seems to have developed some mid-range clag as well.
I'm not convinced it made any different to the running qualities
of either engine until floored, I suspect again not all engines
are equal...
#Post#: 17026--------------------------------------------------
Re: Turn up your Tdi
DIR By: The_Resurrection
Date: March 25, 2012, 4:23 pm
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The problem with any tdi tuning, is that it done with a mirror
and a big hammer ::)
Ideally the first port of call is to make sure all high pressure
inlets are sealed and sealed tight with no leaks. Then mark all
injector pump settings and follow the common tuning guide
available for a tdi. The thing that everybody gets wrong is
failing to set the turbo first before fiddling with the injector
pump.
#Post#: 17030--------------------------------------------------
Re: Turn up your Tdi
DIR By: simdeb
Date: March 25, 2012, 4:57 pm
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Running a 200tdi in the range rover with a well tweak pump and
turbo but the best inprovent was fitting a bigger intercooler
got a big bmw one and what a difference that made
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