a4tdi not well

[thomp1983]

hi my 1998 1.9tdi ahu engined audi a4 is pretty much broken.

problems started with once you got to 80 miles an hour or there abouts there would be a thud like hitting the rev limiter and the turbo would turn itself off, ie. there was no more pull at all even when changing down gears or at lower speeds. turning off the ignition and restarting the car seemed to solve this untilyou hit 80 again. i lived with this for a couple of weeks as i was too busy to look at it,

now it has progressed to there is no turbo at all, as soon as you hit where boost should be the car splutters and struggles and generally it will not rev past 2000rpm although 3000 can be achieved in neutral. im in the process of servicing the car to see if that helps, doing the fuel filter oil and air filter. besides maybe a dirty fuel filter im suspecting the turbo has blown which would be surprising as there isn't any real smoking and it's only done 113k

can anybody offer any advice or suggestions to the problem?
cheers
chris

sorry also forgot to mention since the problems have started my engine temperature goes up and down whilst driving the car, it can vary from as low as 65 up to just under 90 which used to be normal but is now on average settling at 70.

 

[fjtwelve]

On my 1998 1.9tdi110hp Passat i had a power loss problem that would go away when turning the engine off and on again, turned out to be the MAF. I had a previous problem with power loss that turned out to be the temperature sensor when the VW garage said i needed a new turbo. On my current 2001 A6 2.5 TDI giving intermittent full power but mostly lack of power and not revving properly turned out to be the N75 boost control valve, but this also gave smoke. You may have a split air pipe which is bursting open under higher pressure. If the MAF or N75 has gone the engine may be overfuelling in which case it may be running colder but 25C variation sounds too much. Maybe the sensor has gone which then feeding duff data back to the EMU. When you are doing the service clean out the EGR valve, if this is clogged up it will be contributing to the problem. I would be very surprised if your turbo has gone. This engine is also fitted in many VW cars, so visit tdiclub.com where there is more info and problem solving than you ever wanted to know.

 

[thomp1983]

well the new fuel filter has sorted all the boosting/lack of power issue, only one remaining is the temperature situation, i have just fully flushed the cooling system and put in some new antifreeze solution and on the way back from my barn the temp seemed to behave so ill moniter it over the next few days.

are there any bleed points in the a4 cooling system to remove air as i couldn't see any if there were so presumed it may be a self bleeding system

cheers
chris