Tuning an A4 tdi 110bhp/ but boost issue

[simyboye]

Hi there, hope your all well?
I'm picking up an 1998 A4 tdi quattro tdi 110bhp shortly.

It has a boost problem every now and then... when the lack of boost doesn't happen, current owner switches engine of for a second and then it runs fine? Any ideas what that is?

Been Vag-Comed and nothing comes up? Anyone else has this and cured it? Is it electrical or mechanical? Actuator or wastegate? ECU Perhaps? Not used a fault code reader on it.

I want to tune it when I get my hands on it, not too knowledgable on these engines, it wont be a PD engine will it?

Can I fit a 150pd turbo and then Revo it? Is it possible to get 200bhp from it?

Many thanks.
Simo

[mrjolly]

ambitious?
it will probably cost the same to do as the difference in price to buy a car with the right engine in!
pd engines are electronic injection so you will need donor ecu, wiring loom engines aint cheep to buy + immobilisers to sort out. and an auful lot of time.
i personally wouldnt recomend it unless you know what your doing.
i know a guy running 185 hp from a afn 110 hp engine v reliable

[biker_bits]

I had boost issues on my A4 110 Tdi.
They got VNT turbos, so there is no waste gate as the boost is regulated by altering pitch of the impeller on the exaust side.
If the boost comes and goes it may well be the mechanical actuation prob.
Worth checking:
1.the rubber hose going to the vacuum actuator on the turbo is intact and when engine is revved up there the actuator rod moves freely. You should also be able to hear the turbo 'whine'. If it is not - check the valve the hose comes from - it is on the front of the engine block
2. with engine off check the the said rod is attached to the turbo and is free to move all the way in (up) and down (out). I found mine to be very corroded where it attaches to the turbo, as well as the little clip that holds its' pivot pin has fallen out! Bugger to get the new clip in as it is right under the turbo unit, but it can be done without removing the turbo and the exaust - with a bit of patience.

Is the exaust smokey on revv up (as they test them on MOT)?
Is air filter clean?
If so, it may well be a worn MAF (mass air flow sensor) - lives between the air box top cover and the main air hose that runs to the engine. Mine was worn and did not show up on VAG-COM till it completely failed months later. New one (from Euro Car parts, £80 or so exchange) made the car run like brand new! It is very easy to replace too - simply bolt the new one on.

I found extremely useful : http://tdiclub.com/TDIFAQ/ when I was struggling with mine.

[biker_bits]

Sorry... back again.
Just found direct link: http://tdiclub.com/TDIFAQ/TDiFAQ-8.html#e

Just bear in mind that you DO have VNT turbo when you read it.

[simyboye]

Hi there,

Is the exaust smokey on revv up (as they test them on MOT)? NO
Is air filter clean? Think so!
If so, it may well be a worn MAF (mass air flow sensor) - Had a new one a few months ago.

Thanks for your info biker_bits, I think by reading your bits and other threads it might be the N75 or EGR pipe. Will have a sniff about.

Does anyone know how to get big HP out of this engine?
Large injectors, turbo and a remap? Is 200hp possible? What turbo do I need? Will a 150pd turbo fit?

Many thanks

Simo

[biker_bits]

I had to go through 2 new MAFs before as they were 'dead on fit', before finally getting a good one....
N75 is possible - mine was replaced as it was so crudded up that it hardly moved! Had to buy from Audi - was about £50?
Check mechanical actuator though - far too common for it to seize up/disengage from the turbo. Cheap to fix, but often overlooked.