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

but dont put your fingers in when its running

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Originally Posted by md1980

but dont put your fingers in when its running

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:biglaugh: or :crying: lol

...Hi, I haven't been able to check the impeller shaft yet, but i'm pretty sure there is no smoke when i rev the engine when it is warm, My friend seemed suprised that when we removed an air pipe from the front of the turbo the car stalled. He didn't think it should. There was also quite a lot of oil in this pipe. I spoke to someone today who implied that even if it were a problem with the wastegate, I may still need a new turbo, as the fault may be at the wastegate end which would mean it wouldn't make any difference replacing the actuator ( I believe you can buy this seperately?)
Surely the wastegate should only open under load?...just revving it slightly shouldn't cause the shaft to move and vibrate should it? I'm not keen to take it anywhere yet, as I've already spent £400 following the main dealers advice and this has got me nowhere!

i think im right in saying that if theres is oil in the pipes then the chances are the seals in the turbo are leeking. but there again there is quiet a bit of oil in the turbo inlet pipe on my tdi and that still go,s well.

onther way of finding out is to find a long steep hill and keep it in say 3rd/4th gear when you get to the bottem put your foot down hard and see if theres any excessive smoke for a few seconds this will be the oil burning off thats leaked past the turbo seals.

it could also be worn valve stem seals coman on old fords.

Hi, I've got a 100k 1998 1.8t 20v and these are the problems I,ve had and the solutions,

1. Cambelt snapped, what I did:- re-con head using exsisting cams and chain and tensioner, lifters etc (exc old valves), the rattle which sounds the same as yours is the tensioner, they get a little slacker in there old age but it's not been a problem just i bit noisy.
2. Turbo seal and shaft bearing gone (turbine and shaft knackerd and it took 2 weeks to burn the oil out of the cat converter), more smoke than a steam engine when engine was running, what i did:- re-con turbo and gasket etc and act'er set at 7 psi (£250). One problem that I had was the actuator vacuum pipe from the inlet manifold was perished at differanat places along the pipe, so completely replaced, this might be a problem on yours to.
3. Oil pressure light coming on every now and then, what i did:- This is a common fault on this model around 80k onwards. did a couple of engine flushes and 5 oil changes and the problem went away for a week after the oil changes but then came back again, happened about once/twice (some times more) a journey. On this model the pressure reg valve inside the pump sticks and you lose oil pressure (there is still some there and you can drive gently but time is not on your side) the best thing to do is, pull over and switch off the engine wait a couple of seconds and restart this normal unsticks the valve and you will/should get the pressure back. the only fix is to change the pump (£100+ for the pump and £100+ for the fitting, it's a couple of hours job). this is a cheaper option that replacing the engine went it siezes.

Hope this helps.

See above, the tensioner being the rear chain tensioner.

The dump valves on these can leak too, causing a lack of boost pressure.

Sounds to me like a turbo fault! the control rod that operates the wastegate can break leaving the wastegate flap open (no boost) ,this can also cause the ringing noise as the broken rod/flap resonates on overrun.Also your oil light coming on is quite worrying,this engine is common for blocking the oil pickup pipe on the oil pump,especially if pooly serviced/high mileage-suspect your oil change is only a temp cure. Low oil pressure will cause the top end (cam area) to rattle and will kill the Turbo very quickly.The broken rod is quite hard to check/see ,it,s right above the engine mount. obviously this is just a bit of a long shot the fault may be less serious AIR MASS METER or split hose/n75 solenoid problem

Thanks for all the suggestions, very helpful. I changed the oil and filter on christmas eve, there's been no re-occurrance of the low oil pressure light yet, but i'll know to keep a close eye on this. I'm completely convinced the turbo is the problem now, but I need to find someone reliable to take it to, I have someone in mind. The shaft which operates the wastegate just seems to be floating around, any revs at all and it moves backwards, and its completely random how far back it returns. When it does return all the way it makes the rattling noise. A friend has the same model passat but newer ( same mileage though) I had a peek under his bonnet the other day, and the actator bar has a much more deliberate action. It only moves when you rev it highly, and returns solidly. What i'm wondering is whether i'll need to replace the whole turbo or if replacing the actuator would solve it? The VW main dealers have checked it out and said no faults are showing up, and one of their guys has driven it and thought it was fine (this was before I pointed out the rattling noise mind you) so i'm not going to rush back there!

...Oil pressure light came on again this morning!!!!! Damit! It was much colder this morning though, any chance this could be a cause, the last time it came on it was very cold and its been pretty mild since. (sounds wishful doesn't it?)

some early passats suffered siezed engines from using(vw recommended)standard oil,synthetic must be used with all audi/passat engines with turbo's and as a rule all standard non turbo engines.failure to do so leads the oil to harden into a greasy paste(remove your oilcap and put your finger in and feelaround for greasy gritty blackish gunk).if your oil light has been on once then it sounds like trouble on the way.if the oil was not synthetic at service intervals or the car was driven hard your problem could be worn turbo or slack internal timing chain(twin cam).vw lt35's ive known do what you describe with a horrid screech and after a steady idle for 3 minutes it would go away, poor oil change intervals was the problem.only checks to do are:2 vacuum pipes on front right top of engine(one goes to dump valve) remove throttlebody intake pipe(thick bugger)and check it's all clean(never spray carb or injector cleaner into throttle body as fluid washes factory grease out of throttle bushes accelerating wear rapidly) wipe out with a lint free rag.replace your petrol filter as suggested earlier.lastly,remove the undertray and with the car idling listen for the source of the noise you hear and use caution and keep someone nearby to assist you.

..Apologies for being a timewaster. It turns out that the warning light which looks like a flashing red thermometer (which is the same as the water temp gauge above it) is actually a water temp gauge :Blush2: ! I don't have an owners manual, but I can't think why i'd got it in to my head that this was an oil pressure gauge, I MUST have seen something somewhere to make me think that. TW*T! ...Still, its good news tho, a coolant top up will solve that. It also explains why its only been coming on on cold mornings... :rolleyes:

have you checked the condition of the flexi exhaust downpipe under the drivers side seat area of undercarriage.they tear from constant flexing and are costly to replace(+-£180 at quickfit) this would give you a rattle like sound with a bit of rattlesnake type noise only on deceleration as ive found on my passat 1.8t 1998 aeb.remove the throttle body thick black pipe and clean the throat out with a clean lint free cloth,any carb cleaners etc will remove lube in throttle bushes accelerating wear and giving you another costly expence.there is a vacuum hose from the inklet manifold to turbo valve that wears and loss of pressue causes power loss.check the other vacuum hose sort of top right of inlet manifold(short 10cm lenght)this affects fuel pressure at low speeds mainly if leaking.

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Originally Posted by The Stagg

..Apologies for being a timewaster. It turns out that the warning light which looks like a flashing red thermometer (which is the same as the water temp gauge above it) is actually a water temp gauge :Blush2: ! I don't have an owners manual, but I can't think why i'd got it in to my head that this was an oil pressure gauge, I MUST have seen something somewhere to make me think that. TW*T! ...Still, its good news tho, a coolant top up will solve that. It also explains why its only been coming on on cold mornings... :rolleyes:

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Do you require a user manual Stagg? i got one from a american site for free but as it's 300 pages it's best to download and some little bits differ but it's mainly cosmetic bits like swithches or the keyfob.

Passat boy

You are definatly on the right track about your turbo. What happens is the wastegate actuator's diaphragm wears out and becomes useless. With the actuator rod chattering about, this prematurley wears away the bush for the wastegate flap on the inside of the turbo. With actuator and bush worn and flap flapping about = no boost or little boost at high engine speed. Had mine recon'd at a firm called Midland Turbo. They even came to my house to pick it (FOC)up and delivered it back after repair(FOC). Once you get the turbo sorted you will notice a big difference. I did and almost cr*pped myself!! All in all the recon was a little cheaper than actually buying a recon unit.

Thanks for all the input folks. After having a look around the turbo we decided it was best to send it to midland turbo, the wastegate was obviously shafted and there was a lot of oil in the downpipe again (had already emptied it once.) They decided i needed a new unit (no surprises there) and I had it fitted two days ago. It feels much better and has more torque at low revs. I've been told it will loosen up a bit more with some use and power will improve further. Does this sound right? Its better but still doesn't feel quite how i remember it. Would it benefit from (yet another) plug in to some diagnostic equipment, or should i wait?