Loss of Power Whilst Towing Caravan

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
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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)

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Steve Sears schrieb:

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
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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

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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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Des wrote:

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.
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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

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