Max Stock Turbo Boost Pressure? (+ Other Turbo Talk)

What is the max stock turbo pressure on the ALH TDI supposed to be? I've dug into a lot of forums but haven't got a straight answer, all sorts of info from 13-20+PSI.

Background:

I had overboost conditions. Troubleshot: actuator checked out, vacuum seemed fine. So I pulled and cleaned turbo (vanes, levers, control ring, et al). It was a nightmare and filled with soot. Moved great after cleaning. Note: I also did the famous intake/EGR cleaning on the way down to turbo, and had about 50% intake blockage.

Prior to thorough vane cleaning, my boost was peaking around 23PSI. After cleaning it seems to be peaking around 13-14PSI. I haven't got it on the highway to give increased load testing until I get an alignment for the front end I threw on it and eyeball aligned. lol Short story, I haven't proved overboost is gone (it seems better), or load tested. I digress.

The power after cleaning seems a bit lower, but maybe that's the boost level it's supposed to be? After all it wasn't supposed to overboost.

Let me know, and any other suggestions you may have given this situation. I'm new to diesel and turbo so I'm still learning lots.

HI,

Fwiw I heard the limit should be 17 PSI if stock.

I too have had limp mode as a result of an overboost but to date I have not really done anything to alleviate the issue (no intake cleanings, vane cleanings etc...(I did double dose powerservice a few times tho)....

I do drive it mildly hard every once on awhile but I guess not so hard as to make an overboost...well I guess it decided not to overboost I guess.

More recently I got a scangaue 2 and so far the max boost I have seen is about 14 PSI....Maybe I don't flog it as hard as I could / should.....

I don't think I've had it above 3000 RPMs in a long long long long time....

Car seems to do well tho returning 52 or so MPG's on the highway so I'm thinking things are OK...

Andrew

From what I've read 13.5 psi is stock and can be 18 psi (sustained) when tuned up to max for reliability on vnt15. I have overboost too. I changed vac hoses, swapped n18 and n75, adjusted actuator and oven cleaned the turbo. The cleaning stopped limp mode from happening, but still there is an overboost cel. It has full blast power in 2nd while a little sluggish in 3rd. I've been shifting out of 3rd at 50-65, and I don't really use 5th much. I wished I had my psi numbers for you, but I have no gauges. I have 10 months left to get the cel fixed before inspection. Probably a new turbo.

Stock is roughly 14-14.5 or 1 bar. Tuned 18 PSI is about as high as you should go, short bursts up to 20 are okay. The VNT15 is a really tough turbo, but if you want it to live a long life as intended from factory, keeping it around 18 PSI is as far as you should go. Where you'll notice over-boost is if you load it up from around 15-1600 in 3rd/4th until about 2500. That is when the turbo picks up and that's when it could potentially over-spool, due to a lazy N75, over-fueling, vein clogging, poor actuator adjustment etc. Test for worst case scenarios and then work backwards from there. Sounds like your turbo is working just fine!

If it sustains the current status you should be good.
Mine had the same issue and needed replaced.
I recommend pulling the actuator arm from the lever and moving it through its full range.
Feel for any restriction, especially wide open to close.

Mine would open freely, however, it took force to close.
I believe that the adjustment ring got wollowed out where the lever sticks into it.

I am currently experiencing bad boost spikes if I go wide open. pretty much at any RPM. Checked my actuator with mighty-vac. Owain, I sent you an Email about it. Sometimes I wish these cars had wastegates too! AceTDi....let us know how you make out.

I have a brand new vent-15 turbo, squeaky clean intake manifold as well as egr valve. I am still experiencing over boost.

What could be the reason for that? N18? N75?

You have a brand-new vnt-15, which reputable vendor did you buy it from? It shouldn't matter actually as a factory set turbo should already be set correctly. That would leave the N75 valve as being suspect for your problem. Just curious: did you check the actuator travel before you installed the turbo?

Just curious, is there still a cat in the exhaust? With it removed, it will cause boost spikes and over boost. You may need to adjust the rod that controls the vanes in the turbo if this is the case. BTW, my '04 BEW runs at 22 psi at WOT and settles in around 8 to 10 psi.

Joep, that doesn't sound right... By which I mean your boost level

Please remember the boost pressures listed above are for sea level, not for higher altitudes. Joep could you please be a bit more specific about the rpm and load ranges your boost varies at?