Questionhi there. have recently purchased a 2000 (x) model Audi a4 1.9 tdi 115 se. fantastic car. however, under heavy acceleration the turbo comes in fine but half way through it's revs its seems to loose power. between 1500 and 2500 she pulls very strongly and there's no smoke from the back of the car. any idea what the problem could be??
kind regards
mark
Answerwell hi there back!
ok lets start with the simple stuff, you say you recently purchased the vehicle?? does it have a full service history?? if not when was the last time the vehicle was serviced?? whats the current mileage?? its not unusual for previous owners to ignore the service because they are selling the vehicle.
Check the all the filters especially the air filter and diesel filter.
if they are clogged then have the replaced. once this is done and the problem still persists then move on to the harder stuff.
on this model I usually have problems with the intake system, after a few mies I find that Oil and dirt usually clogs the inter-coolers (hidden behind the bumpers.) cleaning usually helps, to do this you'll have to remove the front bumper to gain access to the coolers, I usually use an Industrial solvent like ABRO choke cleaner to get the oil out then rinse it out with degreaser and lots of water and finally blow it out using compressed air. if you decide to do this then make sure ALL of the solvent has been removed and the coolers are COMPLETELY dry before re-installing them, going a step further remove all the inlet pipes and clean them as well to be more thorough.
its also worthwhile checking the diesel filter for water which is more of a problem in cold weather(read winter) and draining it if necessary, but you will have to bleed the system before you can start the car up again, I usually just drain all the diesel out then refill it to the top with diesel before I refit it back.
If none of these steps have rectified the problem then its time to move to the serious and potentially expensive stuff...the Turbo!!!!
does the turbo move smoothly and silently??( a muffled whistling sound is ok, a loud high pitched sound could indicate a leak in the intake or worn out turbo shaft.Check the linkages on the turbo. have some one start the car while you look at the vacuum assembly mounted(waste gate actuator) on the turbo. it should move up smoothly and quickly, if it is sluggish or doesn't rise up quickly or not at all then you could have a stuck valve or weak or defective vacuum pump,( the aluminum oval shaped thing with a pipe sticking out of it,bolted on the cylinder head,directly above the gearbox bell housing.(left hand side viewed from driver seat if memory serves me)but before you decide to change it, follow that pipe that comes out of it and goes into the brake booster, somewhere along the line it will branch off into a small vacuum hose. that hose leads to a solonoid that controls the turbo.(either a small one with 2 pipes or a big box shaped one mounted on the bulkhead with many pipes leading out of it, I have found dirt on the inside of this unit that cause intermittent problems with power,
let me know if this helps,
