Volkswagen Bora (1999 - 2006) - 00 1.9 limp home mode tdi

Honest John Back Room » Technical matters
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Tue 2 Feb 2010 08:10
00 1.9 limp home mode tdi - ark eye
Hi I hope this helps others with my find! I have had this problem with the car going into limp mode (re-sets its self when switched off), after 2 years of putting up with it and putting redex in the diesel I changed the air flow meter, boost control valve and all the vacuum pipes with no change. Last week I pulled the vacuum pipe off the turbo and sucked it (no jokes!) like trying to suck a stone through a straw then I heard a metallic click and like a rusty creaking sound. After doing this a few times it was easier to suck lol and you could here the sound with every time. When taking the car for a test drive what a difference power all through the rev range rather than just high boost for 2000rpm then dropping off. I hope this helps other people as I have spent hours reading about this fault and the cost others have gone through with garages telling people they need a new turbo! Mine was an easy fix but others might not be, one thought if you could make a vacuum stronger than the one used to open the vains on the turbo then this could free it up without having to suck the pipe or strip the turbo?
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Tue 2 Feb 2010 09:17
00 1.9 limp home mode tdi - craig-pd130

That's very interesting, and an inspired fix :-D

It adds weight to the thinking that after a few years of use, the VNT mechanism can start to stick, usually in the high-boost position so it causes overboost and limp home mode.

I'm not sure WHERE the stickiness is, I think sometimes it is in the actuator linkage (due to road crud etc) and sometimes within the turbo housing (due to soot).

I know some people have been able to resolve overboost problems by liberally spraying WD40 on the linkages.

Maybe you could use one of those big turkey-baster syringes (about £1.99 from cookware shops) to do the sucking in future?
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Tue 2 Feb 2010 10:02
00 1.9 limp home mode tdi - 547HEW
For applying high vacuum, repeatedly, to free up the VNT mechanism, I use a bicycle pump with reversed washer. Very effective. (I've incorporated this into the 10,000 mile service routine).
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Tue 2 Feb 2010 11:44
00 1.9 limp home mode tdi - craig-pd130

@547 - how do you couple the vacuum hose to the bike pump? What sort of fitting do you use?
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Wed 3 Feb 2010 07:06
00 1.9 limp home mode tdi - ark eye
maybe a football adaptor might fit stright into the vacuum pipe, might be worth a go?
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Wed 3 Feb 2010 13:19
00 1.9 limp home mode tdi - 547HEW
I use some injector leak off hose (thick walled runbber tubing approx. 3 mm bore), and a couple of plastic (nylon?) screenwasher hose connectors. These are male/male. One of these fits into the vacuum hose leading down to the turbo, then a length of inj leak off hose is attached to that. Finally the pump is connected to the inj leak off hose by the remaining connector. The bicycle pump is one of those have a valve connector on the side of the pump at its base. The valve connector has a thumbwheel to tighten the valve connector onto the valve.

Hope this is understandable!
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