Stuart Thomson

Hi All

I have a 1998 Audi A4 TDI which has been chipped from 110bhp to about
140bhp with no problems for a couple of months until now.

Last weekend I was towing our caravan for the first time. On the
outward journey the car pulled the caravan like a train. There was
loads off power and tourque, in fact on the motorway I didn't have to
change out of fifth gear.

The homeward journey was the same for about the first 50 miles then
all of a sudden the was a very noticeable drop in power. This happened
whilst overtaking lorries up a long up hill drag. The weather was hot
(well hot for England) about 21c. I am no mechanic but my guess was
that the turbo had gone?? There wasn't any extra noise, just a big
drop in power. When we got home I left the car standing for about two
hours then I took it for a spin (without the caravan) and everything
seemed to be fine, power back as normal. So my question is A. What
happened? B. Do turbos stop working when they get too hot? C. Do
turbos have a thermal cut out?

Any advice would be much appreciated.

Many thanks
Stuart

Steve Sears

Stuart,
If you were working the car extra hard, the engine was hot and the turbo was
cramming the air in, it may have been something like predetonation of the
fuel in the engine. What did the boost gauge say when you had the drop in
power? What was the engine temp?
Cheers!
Steve Sears
1987 Audi 5kTQ
1980 Audi 5k
1962 and '64 Auto Union DKW Junior deLuxes
(SPAM Blocker NOTE: Remove SHOES to reply)

"Stuart Thomson" <alesupper@hotmail.com> wrote in message
news:a3c61c80.0406010304.6992c6e0@posting.google.c om...
> Hi All
>
> I have a 1998 Audi A4 TDI which has been chipped from 110bhp to about
> 140bhp with no problems for a couple of months until now.
>
> Last weekend I was towing our caravan for the first time. On the
> outward journey the car pulled the caravan like a train. There was
> loads off power and tourque, in fact on the motorway I didn't have to
> change out of fifth gear.
>
> The homeward journey was the same for about the first 50 miles then
> all of a sudden the was a very noticeable drop in power. This happened
> whilst overtaking lorries up a long up hill drag. The weather was hot
> (well hot for England) about 21c. I am no mechanic but my guess was
> that the turbo had gone?? There wasn't any extra noise, just a big
> drop in power. When we got home I left the car standing for about two
> hours then I took it for a spin (without the caravan) and everything
> seemed to be fine, power back as normal. So my question is A. What
> happened? B. Do turbos stop working when they get too hot? C. Do
> turbos have a thermal cut out?
>
> Any advice would be much appreciated.
>
> Many thanks
> Stuart

Wolfgang Pawlinetz

Steve Sears schrieb:

>Stuart,
>If you were working the car extra hard, the engine was hot and the turbo was
>cramming the air in, it may have been something like predetonation of the
>fuel in the engine. What did the boost gauge say when you had the drop in
>power? What was the engine temp?

I think there's no boost gauge on an A4 TDI.

I rather guess the MAF gave in and then the power dropped. Now without
the caravan the powerloss is not that noticeable, but it might well
still be there.

I'd say have the MAF checked. It's not recorded in the car's onboard
telemetry. There's a test drive cycle you gotta run to identify the
problem.

Regards

Wolfgang
--
* Audi A6 Avant TDI *
* reply to wolfgang dot pawlinetz at chello dot at *

Des

Could it have been Stuart Thomson who typed:

|| Hi All
||
|| I have a 1998 Audi A4 TDI which has been chipped from 110bhp to about
|| 140bhp with no problems for a couple of months until now.
||
|| Last weekend I was towing our caravan for the first time. On the
|| outward journey the car pulled the caravan like a train. There was
|| loads off power and tourque, in fact on the motorway I didn't have to
|| change out of fifth gear.
||
|| The homeward journey was the same for about the first 50 miles then
|| all of a sudden the was a very noticeable drop in power. This
|| happened whilst overtaking lorries up a long up hill drag. The
|| weather was hot (well hot for England) about 21c. I am no mechanic
|| but my guess was that the turbo had gone?? There wasn't any extra
|| noise, just a big drop in power. When we got home I left the car
|| standing for about two hours then I took it for a spin (without the
|| caravan) and everything seemed to be fine, power back as normal. So
|| my question is A. What happened? B. Do turbos stop working when they
|| get too hot? C. Do turbos have a thermal cut out?
||
|| Any advice would be much appreciated.
||
|| Many thanks
|| Stuart

This might sound too simplistic! but I have been called out to a number of
breakdowns with the same symptoms as yourself, one turned out to be the
caravan hub had started to seize and the car in trying to tow it had
destroyed the clutch!!! and I had one where the car was OK but the caravan
needed a new axle, Both drivers thought it was the car losing power..
Another strange one was a vauxhall 2L injection which had gone into limp
mode, turned out to be a short on the caravan wiring, which caused a voltage
drop on the car causing the ECU to see a problem, a new plug and the ecu
reset and off he went...
try the simple solutions first, when was the last time we stripped something
down to find it could have been cured in 30 seconds! (actually, for me last
week!!!)

Des.




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Chris Bartram

Des wrote:
> Could it have been Stuart Thomson who typed:
> Both drivers thought it was the car losing power..
> Another strange one was a vauxhall 2L injection which had gone into limp
> mode, turned out to be a short on the caravan wiring, which caused a voltage
> drop on the car causing the ECU to see a problem, a new plug and the ecu
> reset and off he went...
> try the simple solutions first, when was the last time we stripped something
> down to find it could have been cured in 30 seconds! (actually, for me last
> week!!!)
>
> Des.
>
That's a very real possibility. A fault with the brakelights (or one of
the two brake pedal switches!) can put the ECU on a VW/Audi TDi into
limp home- it usually flashes the glowplug light when it detects the
fault though. The loss in power is dramatic, and it does indeed feel
like the turbo is not working. Check the tdiclub forums at
http://www.tdiclub.com for useful info. I've heard of one A4 that
returned from a bodyshop performing badly and the bodyshop had forgotten
to reconnect the rear lights! Connecting them up cured it.

Stuart Thomson

Hi Steve, thanks for your reply. My A4 does not have a boost gauge
unfortunately. The temp gauge was at the normal 90c.

Cheers, Stuart

"Steve Sears" <steve.sears@SHOESsoil-mat.on.ca> wrote in message news:<Ze%uc.16998$Hn.547372@news20.bellglobal.com> ...
> Stuart,
> If you were working the car extra hard, the engine was hot and the turbo was
> cramming the air in, it may have been something like predetonation of the
> fuel in the engine. What did the boost gauge say when you had the drop in
> power? What was the engine temp?
> Cheers!
> Steve Sears
> 1987 Audi 5kTQ
> 1980 Audi 5k
> 1962 and '64 Auto Union DKW Junior deLuxes
> (SPAM Blocker NOTE: Remove SHOES to reply)
>
> "Stuart Thomson" <alesupper@hotmail.com> wrote in message
> news:a3c61c80.0406010304.6992c6e0@posting.google.c om...
> > Hi All
> >
> > I have a 1998 Audi A4 TDI which has been chipped from 110bhp to about
> > 140bhp with no problems for a couple of months until now.
> >
> > Last weekend I was towing our caravan for the first time. On the
> > outward journey the car pulled the caravan like a train. There was
> > loads off power and tourque, in fact on the motorway I didn't have to
> > change out of fifth gear.
> >
> > The homeward journey was the same for about the first 50 miles then
> > all of a sudden the was a very noticeable drop in power. This happened
> > whilst overtaking lorries up a long up hill drag. The weather was hot
> > (well hot for England) about 21c. I am no mechanic but my guess was
> > that the turbo had gone?? There wasn't any extra noise, just a big
> > drop in power. When we got home I left the car standing for about two
> > hours then I took it for a spin (without the caravan) and everything
> > seemed to be fine, power back as normal. So my question is A. What
> > happened? B. Do turbos stop working when they get too hot? C. Do
> > turbos have a thermal cut out?
> >
> > Any advice would be much appreciated.
> >
> > Many thanks
> > Stuart

Stuart Thomson

Hi Des, thanks for replying to my post.

I don't think it is the caravan hub or axle because I was able to push
the caravan myself to park it when I got home. The electrical fault
could be a possibility though because my plugs were very old and
corroded. In fact my drivers side signal was not working until I
wriggling the plug a bit. I have just replaced the plugs with new
ones tonight so if it was that that caused the ECU to go into limp
mode then it shouldn't happen again now.

Thanks again
Stuart


"Des" <desmond@orange.net> wrote in message news:<2i3jvdFih655U1@uni-berlin.de>...
> Could it have been Stuart Thomson who typed:
>
> || Hi All
> ||
> || I have a 1998 Audi A4 TDI which has been chipped from 110bhp to about
> || 140bhp with no problems for a couple of months until now.
> ||
> || Last weekend I was towing our caravan for the first time. On the
> || outward journey the car pulled the caravan like a train. There was
> || loads off power and tourque, in fact on the motorway I didn't have to
> || change out of fifth gear.
> ||
> || The homeward journey was the same for about the first 50 miles then
> || all of a sudden the was a very noticeable drop in power. This
> || happened whilst overtaking lorries up a long up hill drag. The
> || weather was hot (well hot for England) about 21c. I am no mechanic
> || but my guess was that the turbo had gone?? There wasn't any extra
> || noise, just a big drop in power. When we got home I left the car
> || standing for about two hours then I took it for a spin (without the
> || caravan) and everything seemed to be fine, power back as normal. So
> || my question is A. What happened? B. Do turbos stop working when they
> || get too hot? C. Do turbos have a thermal cut out?
> ||
> || Any advice would be much appreciated.
> ||
> || Many thanks
> || Stuart
>
> This might sound too simplistic! but I have been called out to a number of
> breakdowns with the same symptoms as yourself, one turned out to be the
> caravan hub had started to seize and the car in trying to tow it had
> destroyed the clutch!!! and I had one where the car was OK but the caravan
> needed a new axle, Both drivers thought it was the car losing power..
> Another strange one was a vauxhall 2L injection which had gone into limp
> mode, turned out to be a short on the caravan wiring, which caused a voltage
> drop on the car causing the ECU to see a problem, a new plug and the ecu
> reset and off he went...
> try the simple solutions first, when was the last time we stripped something
> down to find it could have been cured in 30 seconds! (actually, for me last
> week!!!)
>
> Des.
>
>
>
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.692 / Virus Database: 453 - Release Date: 28/05/2004