boost keeps climbing

So last night on my way home running veggy cruising along, i see another golf pull up behind me real quick so i pull into the next lane and let him pass, then i notice it's another TDI.

WELL i wasn't going to let that happen

so we had some fun until it finally cleared up so we both punch it. I'm sure his car was not stock either as it pulled pretty damn hard, even though i could real him in quickly.

But i noticed that my boost would peak at about 24 then settle down to 22 but then would start to rise again all the way to 28-30.

and on the last go at it with the other TDI, as i'm just about to go by him i went into limp mode at about 180kph. DAMN!!

So i pulled in behind him and we both cruised at about 140 till he took an off ramp.

So what could be making my boost to continue rising, Could it be to much vacuum in the N75 line coming from the airbox?

my VNT17 is only about a year old so i doubt if it's the actuator and i have a boost valve.

any thoughts.

I have the same problem with my VNT-15. There is no peak for my boost it just goes up and and up and up. At part throttle I can cruise at a steady psi between 10-15psi and I'm afraid to go WOT because before I can push it all the way to the floor the boost is well over 30psi. I have tried adjusting the acumulator arm length to be all the way short and all the way long, I have tried straight vacuum from the pump to the 75 valve, I've tried no vacuum on the actuator and there is no change whats so ever.

I have a new turbo on the way and I have parked my car. I think the VNT mechanism is jammed or has some sort of other damage. Time will tell.

Dirty vnt vanes. If you don't have an EGR. Simply remove the EGR block plate. Spray carb cleaner, or a product called Sea Foam.. Work the VNT vanes with a mightyvac. Spray more cleaner and work the vanes.

Drive the car - but beware it will blow blue smoke like a wore out dirt bike on steroids! My car used to overboost and cleaning the VNT vanes worked. I now run different software and have yet to see this happen.

I have the same problem. Except boost climbs up and up to 22psi when i go in to limp mode, only at WOT or close to it. But my car has less than 11k miles, and ive been using B20 & stanadyne so I would not think there could be much of anything on the VNT vanes. I also have a Boostvalve and it cuts down the spikes to 14-17psi ish but at WOT it just climbs hard. As a result i realy never go WOT. Any ideas? Besides abusing it less...

My old Turbo did the same thing as the OP, it was the vanes inside. I worked it and worked it over a fe weeks (moving the actuator by hand) and installed a boostvalve and that seemed to cure it. Try the carb cleaner for sure, running veggie maybe it has gummed up faster than you think.

I had that problem with my old moddified vnt15... changed to a vnt17vb and its ok.
So it was too much fuel for a small turbo.

SBA, your problem may/is a little different than GuyGuy's. His is an 01 Golf, while yours is a PD. so there are way different things going on. G60ing probably nailed his problem. SBA, yours is another problem that seems inherent with the PD when they are chipped. as as you have RC it seems more like a problem that most of us Chipped PD owners have. here is an old Post talking about the problem with the PD, it is still not solved, as most signs point to the Turbo and its inability to exhaust fast enough.

Here is the thread: http://forums.tdiclub.com/showthread.php?t=128602

And be prepared it is a pretty long thread but it will lay out a lot of things. again this is for the PD, not the ALH engines

Eric B

TDikook said:

SBA, your problem may/is a little different than GuyGuy's. His is an 01 Golf, while yours is a PD. so there are way different things going on. G60ing probably nailed his problem. SBA, yours is another problem that seems inherent with the PD when they are chipped. as as you have RC it seems more like a problem that most of us Chipped PD owners have. here is an old Post talking about the problem with the PD, it is still not solved, as most signs point to the Turbo and its inability to exhaust fast enough.

Here is the thread: http://forums.tdiclub.com/showthread.php?t=128602

And be prepared it is a pretty long thread but it will lay out a lot of things. again this is for the PD, not the ALH engines

Eric B

Click to expand...

Eric,

Thanks for the link! Its been bookmarked will read all of it as soon as i have more time! Glad there are so many out there who know 100X as much as I do, well thanks again, looks like ive got some more reading to add to my list, lol.

Steve

Last night I checked the VNT vanes and they move freely

Another member mentioned to me that it's probably the N75 that's pooched.

I unpluged the hose from the airbox to make sure it wasn't pulling to much vacuum and it's the same, tonight i'll try and listen for the ticking, I'm thinking that's what went wrong. If it's that then i'll try cleaning it with electrical contact cleaner and well if that don't work then it's time for a new one. OUCH! i gess they ain't cheap either. I also heard that the N75 is used in the G60 gasser motor. Is this true?

GuyGuy said:

I also heard that the N75 is used in the G60 gasser motor. Is this true?

Click to expand...

no, the G60 goes not use any electronic technology other then its ISV to control boost levels and most people bypass its boost control function.

I believe you mean the 1.8T used in Mk4s

GuyGuy said:

Last night I checked the VNT vanes and they move freely

?

Click to expand...

Feeling the vanes on a cold non running engine is not the same at a hot engine pushing 2000-4000 rpms.

Several times I cleaned my vanes and they allways "felt" clean. But after the cleaning there were no boost spikes. Don't relie on "feeling" the vnt vanes by hand.

03_01_TDI said:

Feeling the vanes on a cold non running engine is not the same at a hot engine pushing 2000-4000 rpms.

Several times I cleaned my vanes and they allways "felt" clean. But after the cleaning there were no boost spikes. Don't relie on "feeling" the vnt vanes by hand.

Click to expand...

x2

I saw that on a dyno... in cold the vanes were ok , at a dyno run you could see that the actuator wouldnt move..

03_01_TDI said:

Dirty vnt vanes. If you don't have an EGR. Simply remove the EGR block plate. Spray carb cleaner, or a product called Sea Foam.. Work the VNT vanes with a mightyvac. Spray more cleaner and work the vanes.

Drive the car - but beware it will blow blue smoke like a wore out dirt bike on steroids! My car used to overboost and cleaning the VNT vanes worked. I now run different software and have yet to see this happen.

Click to expand...

It would be best to remove the (2) 10mm bolts holding the vacuum actuator to the turbo housing. I also take the c-clip off the arm as well but, not necessary. This process may not work well for those who reside in a salt belt part of the country due to these bolts being very difficult to remove. After you carefully add the carb cleaner or Seafoam, you can then move the VNT arm very fast and more frequently than using a Mity-Vac. In other words the aggitation effect will be faster and more thourough and will most likely clean it much better. Later!

agree with that. You can also use a large screwdriver and carefully press down on the vnt arm.

All that is good to check but still doesn't proof it the mechanism works under hot conditions. Although it shouldn't change anything due to expansion of materials. It doesn't get that hot to have changes outside of tolerance windows of the gaps between the vanes and the base surface.
I'm still thinking of hooking up my mityvac to the outlet at the airfilter housing for the boost vent hose from the N75. It does make a considerable difference when I unhook it from the filter housing and stick a RC model fuel filter to the end of the hose. I noticed a much faster boost dump during shifts and faster dial in too. I'll have to run a vagcom log to proof it. I'm very new to Vagcom so it'll be a while until I figure out all the options.

Eck said:

All that is good to check but still doesn't proof it the mechanism works under hot conditions. Although it shouldn't change anything due to expansion of materials. It doesn't get that hot to have changes outside of tolerance windows of the gaps between the vanes and the base surface.
I'm still thinking of hooking up my mityvac to the outlet at the airfilter housing for the boost vent hose from the N75. It does make a considerable difference when I unhook it from the filter housing and stick a RC model fuel filter to the end of the hose. I noticed a much faster boost dump during shifts and faster dial in too. I'll have to run a vagcom log to proof it. I'm very new to Vagcom so it'll be a while until I figure out all the options.

Click to expand...

Maybe so but, This carb cleaner/Seafoam procedure is a last ditch effort before having to remove the turbo. Very much worth this effort if it ends up cleaning the vnt enough to keep the overboost at bay. If it improves the overboost but not completely solves it, you can then add a boost valve and then set it not to overboost. This will give you some time before the point of no return of having to remove, rebuild, or replace the turbo. Later!