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Discussion Starter #1
Hi all,

Greetings, and thanks for having me onboard.. My problem concerns my 2005 Passat B5.5 PD130 (AWX engine) estate...

The problem:
- The power from the engine is lower (not like an inoperative turbo kind of low) - maybe 70% of what it should be up until around 2200rpm, then it gets all the torque back and takes off like a rocket (much steeper change than normal turbo lag). There is also very bad engine vibration on idle (all the hoses etc jumping around if you watch the engine) and all the way up to about 2000 rpm, upon which all the vibration disappears completely. The vibration only happens when the engine is hot, it isn't noticeably there when the engine is cold. The vibration is worse under heavy load/acceleration and sounds slightly resonating. It's not coming from driveshafts/suspension etc.

Other info:
- The problem started at the time when I noticed two things: I'd slightly overfilled the oil (which I fixed), and I also noticed that the timing belt was slightly loose. Now this looseness wasn't bad, I read the torsion angle on VCDS and it was only at 1.7 degrees (up from the normal 0.6 degrees). I had the cambelt tensioner adjusted and it's been fine for the last 5 months
- The car has for a long time emitted some unburnt diesel (ie it stinks). I think there may be a slightly faulty injector perhaps which dribbles out fuel after the main injection, but VCDS shows all injectors well within deviations, typically get something like -0.66 -0.21 0.35 0.52. The idle isn't rough either so it's not like there's obviously running on 3 cylinders or something...
- The MPG is pretty normal - perhaps slightly lower than optimal, I get about 46 mpg measured at the tank (factory spec on this car is 47.9) . The computer reads about 4% more optimistic
- It starts, idles and drives reliably - just with the power loss and vibration
- There are no faults on VCDS (apart from the EGR which i've disconnected)
- It doesn't smoke at all (with the EGR disconnected)
- The car's done 130k, but it's been regularly serviced (with the right Quantum oil since I've had it)
- Cambelt, pump and tensioner were done at 100k

What i've checked (ie what it's not I think):
- Timing: I've tried setting the torsion value on different settings between 2.2 degrees advanced to 2.2 degrees retarded. I've currently got it set to 0.6 degrees advanced which is normal. The vibration does get less with retarded timings, but it's still noticably there and when retarded I lose even more power. When the timing is set, it stays there so i'm sure that the timing belt etc it ok
- Turbo. I've tried disconnecting the vacuum to the turbo (so it's disconnected), however I still get the vibration. Boost is fine and i'd replaced the N75 last year so I'm sure this should be ok (ie I know what it felt like when faulty)
- EGR. I've disconnected this. Car generally drives a bit better, but it doesn't affect the power/vibration
- Flywheel: Not checked, but the vibration is there when driving in all gears up to 2000 rpm. If the DMF was failing, i'd expect the vibration to go when the clutch was engaged?
- I've logged all the usual stuff (MAF/MAP/IQs etc) while driving, and there was nothing obvious in the values
- I couldn't hear anything obvious listening to various parts of the engine when idling (with the engine top cover removed)
- It's not really got worse or better in 5 months, but it worries me and is annoying that I'm lacking power and have vibration

So remember that the vibration is only really bad when the engine is hot, and I'm lacking power <2000 rpm.

I'm not sure what else to check... I don't believe that it's general engine wear, as i'd expect it to be worse at cold (there's no sign at all of blue smoke, piston slap etc etc).

Things I've wondered about are:
- Could it be related to the camshaft, or the PD injection stroke adjustment (injector cam followers)? I've had a look at the camshaft and couldn't see any scoring or obvious wear (though I didn't have a new one to compare it to)
- Could it have damaged something when the timing belt was slightly loose? I'd find this hard to believe as when it was in this condition, the torsion value only changed by about 1 degree from normal

Any help of things to check or pointers would be really appreciated! I've attached a recentish log of some of the engine blocks if that helps.. View attachment LOG-01-004-011-015_0.6 advanced.CSV.zip

Many thanks

Lee
 

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Have you checked the turbo actuator and the vacuum lines? What state of repair are your motor and transmission mounts in?
 

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Discussion Starter #3
Hi, the N75 and vac lines were replaced 9 months ago. The boost is fine and I've checked the vac system with a vacuum gauge.

I had a new transmission mount a while back which is still fine, but will double check the motor mounts - though I think it's unlikely to make a big difference if the engine is hot or cold?

Thanks
 

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Discussion Starter #6
Hi there, I don't believe that the 1.9 PD130 (AWX) has a balance shaft. I think that was 2.0 and US cars? Does anyone know 100% on AWX?
 

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Discussion Starter #7
Hi, yep I'm familiar with the actuator rod. I don't think there's any issue with it (eg sticking etc), and I'm not sure that having a hot or cold engine would change the behaviour?

To explain further:

- Start driving with cold engine. Everything seems to be ok - no bad vibrations and power is there
- Engine gets up to temperature... Bad vibrations on both the power band from 1.5-2.0k rpm, and on idle
- If engine cools down (engine off or lots of coasting :) ) then the vibrations become less and power returns

It is so strange... I checked the motor mounts as suggested, but I can't see anything amiss.

Thanks for everyone's input, please keep the ideas coming.
 

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The AWX doesn't have a balance shaft.

I've reread your posts and can't think of anything other than maybe the timing belt skipped when the tensioner loosened. If I were in your situation, I would physically check to make sure the timing is still correct (cylinder 1 TDC and all marks lining up) but with the torsion value being so close I'm not 100% positive it skipped.

Have you tried posting over on tdiclub.com or myturbodiesel.com to see if anyone there has more information?
 

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Discussion Starter #9
Thanks - will check the timing marks this weekend. I think it's unlikely too though, as with the torsion value being correct, the adjustment bolts are in the centre of the curved slots on the cam sprocket. If i'd adjusted the timing to be correct but the sprocket was 1 tooth out, I would expect the bolts to be at an extreme end position in the slots?

I will check though, just to rule it out...

Cheers
 

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If i'd adjusted the timing to be correct but the sprocket was 1 tooth out, I would expect the bolts to be at an extreme end position in the slots?
^^^ Yes, if the tensioner had been correctly readjusted. Did you do the work on the tensioner yourself?
 

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Discussion Starter #11
No, it was done by a VW specialist. I'm not sure what difference that makes though, the timing can't be massively out and the engine run near to normal, surely?

My point is that with the bolts near the centre of the adjustment range, and the torsion value being close to zero, how can it be out by a tooth or more?

Cheers
 

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No, the engine wouldn't run as well as you describe if the timing were too far off. I understand the concept you are explaining about the bolts being centered or nearly centered.

But if the tensioner wasn't adjusted correctly, by someone not knowing what they were doing or paying attention, then it is very possible the tensioner could compensate for the belt having skipped. Considering it was done by a VW specialist I think my theory is no longer valid.

I'm am curious what will be the fix for your problem.
 

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Discussion Starter #13
Hi all,

Sorry for the delay in replying - it's taken a while to make any progress. Basically I did the "Mr Muscle oven cleaner" turbo cleaning, and the vibration / loss of power under acceleration is now pretty much gone, and it's much smoother without the "strangulation" around 1800-2200 rpm! I only managed to get half a can of oven cleaner in, so I might be tempted to repeat the procedure so that the turbo is as clean as possible!

I still have some vibration at idle, though this doesn't seem to get worse with temperature now. Perhaps it's the alternator pulley, but it's not too bad so I'm not that concerned!

Many thanks for the tips!

Lee
 
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