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Sticking vanes - any total solution?
- Thread starter iain1970
- Start date
Why would you fit a new one? Get cleaning the thing and make sure and thrash it in future. 
http://forums.tdiclub.com/showthread.php?p=1340914
http://forums.tdiclub.com/showthread.php?p=1340914
It's driving to soft all the time that generally causes most of the trouble with the vnt, if you get the car up to temp and give it a bit of a razz once a week or so or at least get it upto the red line you'll virtually kill this problem. Going wastegate is a total step backward and you'll also end up with big lag on anything over 125ish which is roughly the limit of the wastegate on the tdi. People have this wierd notion that tdi cars shouldn't be driven so hard but it's total nonsense and wont do any harm. I'm not suggesting you race the tits off it all the time but just don't drive it like a granny either.
Long-term fixes are to defeat or delete the EGR valve and reroute the PCV valve into a catch can. This will eliminate the prime causes of soot in the TDI exhaust.
Short-term, find a longish uphill section of A road or motorway and drive up it at full revs in third gear. This gets the turbo hot enough to burn off the carbon deposits in the exhaust turbine which are the main cause of sticking vanes. Four or five minutes will make a difference to the engine that you should be able to feel. Obviously make sure you aren't overdue for a service and that your oil and coolant levels are good.
Short-term, find a longish uphill section of A road or motorway and drive up it at full revs in third gear. This gets the turbo hot enough to burn off the carbon deposits in the exhaust turbine which are the main cause of sticking vanes. Four or five minutes will make a difference to the engine that you should be able to feel. Obviously make sure you aren't overdue for a service and that your oil and coolant levels are good.
yes agreed with whats been said, you either remove the two things (CCV and EGR) that cause the issue or you just make sure you drive nice and hard, a healthy TDI is a hard driven one.
I do drive with gusto, so it's largely down to poor design of the system rather than a weak right foot.
Hey ho. I honestly can't see the merit of getting it cleaned. Labour for removal and refitting, together with replacement oil, filtre and oil feed pipe are going to be the same, so there's just the matter of comparing the cost of a new turbo against paying labour to have the current one split and cleaned. At least a new turbo will be covered by a warranty for a period of time.
Hey ho. I honestly can't see the merit of getting it cleaned. Labour for removal and refitting, together with replacement oil, filtre and oil feed pipe are going to be the same, so there's just the matter of comparing the cost of a new turbo against paying labour to have the current one split and cleaned. At least a new turbo will be covered by a warranty for a period of time.
Well if you're just geting a new one a chucking the old one I'll give you my address
Seriously, do it yourself, a new turbo costs a fair whack and I think yours is all in one with the manifold on the BKD too which means it costs even more! You'd be bonkers to replace it just because the vanes are sticky. If you clean it properly it'll last for ages and if you do the egr removal etc as well you shouldn't need to do it again. It could also just need an actuator, might not be the vanes at all, that's just one possiblity.Then the vanes aren't your problem, actuator, N75, leaking boost pipe, dodgy map sensor, dodgy maf sensor, bad map, leaking vac pipes etc.
Well if you're just geting a new one a chucking the old one I'll give you my address
Before I replied, I had to refresh my thoughts on how a VNT turbo worked. Now that I have, I understand the VNT is on the turbine (exhaust) side, not the compressor side. By removing the EGR, how is this going to reduce carbon from the exhaust passing through the turbine?
As I said above, the EGR is the main cause of soot in the TDI exhaust. EGR intentionally reduces the oxygen content of the charge by injecting exhaust gas, with the intention of reducing the burn temperature, so as to inhibit the formation of Nitrogen oxides, NOx, in the cylinder.
So, the charge fuel-air ratio is intentionally disturbed, leading to incomplete combustion and hence soot formation.
Completely neglecting the fact that higher burn temperatures are more efficient.
It is accepted that these NOx reduction methods cause an increase in particulate emissions, but the little green Californians deem this to be acceptable.
So removing the EGR reduces soot formation by the engine. Win all round.
So, the charge fuel-air ratio is intentionally disturbed, leading to incomplete combustion and hence soot formation.
Completely neglecting the fact that higher burn temperatures are more efficient.
It is accepted that these NOx reduction methods cause an increase in particulate emissions, but the little green Californians deem this to be acceptable.
So removing the EGR reduces soot formation by the engine. Win all round.
A bloody good thrash should sort that out and use decent fuel too, you could even run some diesel purge through the system to clean up the injectors. The turbo compresses the air to get more in to the cylinder to raise the combustion pressures for burning the fuel efficiently, the chances are your turbo might not have been running at its full potential causing extra soot/smoke. The other thing that can effect your emmissions is dirty injector tips so dealing with the two things should really sort that right out.
wots n75, and map n maf sensors there is no codes its been read loads of times in the past 4 months and on 3 diffrent computers including seats and vw's computer
You don't always get a fault code, you need to try testing stuff sometimes to get to the bottom of the problem
http://www.myturbodiesel.com/1000q/multi/limp-mode-TDI-fix.htm
http://www.myturbodiesel.com/1000q/multi/low-power-fix-TDI.htm
Even a clogged intake can cause limp mode but it wont throw a code, a leak around the egr valve etc
The N75 is the valve that opens and closes to allow the vacuum through to vary the boost pressure, the map sensor is what detects the pressure in the boost pipes etc to determine how much boost there is, maf sensor tells the ecu how much air is coming into the intake from the airfilter. One of the things you could do is to get someone who knows how to use vagcom to run some logs, they can tell you various things that are going on as you drive.
http://www.myturbodiesel.com/1000q/multi/limp-mode-TDI-fix.htm
http://www.myturbodiesel.com/1000q/multi/low-power-fix-TDI.htm
Even a clogged intake can cause limp mode but it wont throw a code, a leak around the egr valve etc
The N75 is the valve that opens and closes to allow the vacuum through to vary the boost pressure, the map sensor is what detects the pressure in the boost pipes etc to determine how much boost there is, maf sensor tells the ecu how much air is coming into the intake from the airfilter. One of the things you could do is to get someone who knows how to use vagcom to run some logs, they can tell you various things that are going on as you drive.
dazvessey, please describe the symptoms you are getting as fully as possible. All I can see from you in this thread is "its still playing up". Playing up how?
The N75 valve is part of the control system for the turbo. It converts electrical signals from the ECU into a low pneumatic pressure (between atmospheric and zero, or at least as low as the vacuum pump can manage) and this pressure sets the angle of the variable-geometry vanes in the exhaust turbine of the turbcharger.
MAP is Manifold Absolute Pressure, and the MAP sensor tells the ECU what the pressure of the inlet charge is.
MAF is Mass Air Flow. The MAF sensor tells the ECU the mass of the air that is taken in by the turbo.
The N75 valve is part of the control system for the turbo. It converts electrical signals from the ECU into a low pneumatic pressure (between atmospheric and zero, or at least as low as the vacuum pump can manage) and this pressure sets the angle of the variable-geometry vanes in the exhaust turbine of the turbcharger.
MAP is Manifold Absolute Pressure, and the MAP sensor tells the ECU what the pressure of the inlet charge is.
MAF is Mass Air Flow. The MAF sensor tells the ECU the mass of the air that is taken in by the turbo.
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looses power foot flat to the floor and its as flat as a fart till it gets to 2500/3000rpm jerks under acceleration like its miss firing
its had vag com on it evry thing was fine did over 200 miles wiv it conected up never missed a beat
im gonna say possible dead MAF, you have vag com log the MAF and boost, requested vs actual and graph up to see where the issue is.
www.ross-tech.com/vag-com/cars/tdi.html
www.ross-tech.com/vag-com/cars/tdi.html
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