Lack of power on 1.8 turbo petrol

Greetings! I have been trawling through some of the topics listed on the forum, and thought i'd post a query of my own. I recently purchased (3 months ago) a 1997 Passat 1.8 turbo petrol with an AEB engine code. Approximately 5-6 weeks after buying it i noticed a real drop in power, with a considerable drop in torque. I foolishly took it to the main dealer (it was very close to where i work) They diagnosed a faulty throttle body, which has been replaced and made no difference to power. Last week the oil pressure warning light came on (without being low on the dipstick), I changed the oil and the filter and this cured the problem. I also changed the spark plugs and the air filter in case poor servicing was the problem, this has made no noticeable difference to performance but both needed doing. When driving the car, if you take your foot off the throttle there is a high pitched ringing noise from the engine compartment. This is noticeable in confined areas with the window down. When i pointed this out to the VW mechanics they said it may be the chain that drives the rear of the engine, they said a tensioner may have gone. Any thoughts? Could this cause a drop in power?
I have read another posting about a deisel turbo that may have had a drop in power due to an over conservative driving style, something about deposits building up on the turbine?? Could this effect petrol models as well? This would make sense, as this is the first car i've had with a trip computer, so I have been driving as economically as possible to see how far a tank will get me! Any thoughts anyone?

in my eyes if the tentioner for the chain had gonna you would have a bigger problem than what you have at the moment

may be a boost leak ie intercooler pipe split ect the n75 valve may have gonne faulty diverter valve (dump valve) air mass meter full of **** the list can go on .easy way to check it would be if you have a boost gauge at leastt you can see if your making boost or not


hope that helps

Check for boost leaks(splits, disconected boost hoses) as there should be no high pitched noise comming from the engine, also check the MAF and see the engine mileage or the service history for when the cambelt was changed.

Thanks for the suggestions, when I get a bit of free time and daylight i'll do some more investigating. The noise i described isn't a constant noise, I guess its more of a rattle. I originally thought it was the exhaust blowing or vibrating somewhere but i've had this checked out. I've got very little history i'm afraid, the car is on 82k, the guy who sold it to me give me a signed guarantee that he'd just changed the cambelt, but I have no physical proof of this as such. If the timing were slightly out, would this reduce performance slightly without making it run horrendously? Thanks again, i'll look into it. Oh, by the way, they also tried an air mass meter, but this made no difference so they put the old one back in so that i didn't have to pay for it.

....I do have a log book with stamps in it at the correct mileages by the way... i forgot about that!

if the timing was out it would make a diffrence if this was the case it would have been like that when you picked it up i would of throught .was it okay when you picked the car up and the power has slow gone ????

also... have you noticed any noises fromn the fuel pump??? have you changed the Fuel filter when you serviced it as this always gets missed..

RiCKT

Hi, I'm pretty sure the car was fine when I got it, as I have noticed the drop off in power. If i'd had it longer i'd probably have noticed it sooner. I haven't changed the fuel filter yet, no. It was next on my list but its not the easiest of jobs is it? I'll attempt to get this done at the weekend... hopefully thats what it is! Thanks again.

Right, here goes! I've changed the fuel filter this avo. I spent the rest of the afternoon with a mechanic friend of mine having a thorough look at everything we could think of. I was keen to find the source of the noise, and we think we may have. We believe there is a problem with the turbo wastegate, we think the bar connecting the actuator to the wastegate is not attached on one end or the other. Either this or there is a spring which has broken inside the actuator. There is movement in the bar when you rev the engine, and when you drop the revs is doesn't always go back all the way. When you wedge the bar with a screwdriver and rev the engine, there is no rattling noise. I'm optimistic! Anybody think i'm bonkers?!

take the outlet pipe off the turbo think you,l have to remove the air box stick your finger inside and see if theres any play in the impeller shaft.
also leave the car run for a while when hot and see if theres any smoke when reved