VNT 17/22 making a strange buffeting noise at WOT/high boost

[tyson]

Lengthen the rod a 1/2 turn. tighten the nut. Drive. Rinse repeat till it goes away. Then when you get your retune, reset the rod to where you started and see if it's still there. Step away from your perfectionism for a moment and "make it work" till you can get the new tune in.

Or another crude method would be to use VCDS and adapt your IQ # up to reduce some fueling and see if that helps.

That sure does sound like surge to me vs regular ol' 17/22 whine.


BTW. turbo isn't from ebay or a strange seller is it?

Thanks man. I understand now, its a temporary fix while I'm waiting for my new tune. Turbo is new from Paul at Kerma

 

[Bob_Fout]

Even with upgraded IC pipes, bigger SMIC, OMI-style TIP, 2.5" and 3" exhaust, stock and SRI airbox, mine has never made that sound.

 

[KERMA]

You are in utah
If you don't get a response from Malone, stop by the house and I will load a file into your car that will work for you until you can get help with your tune.
(but I suspect that now you WILL get a response, you're welcome!)

 

[faboka]

I'd be interested to see a 3rd gear boost log of this.

 

[asap03]

Is this a adjust and drive to see kind of adjustment or can I view the results in VCDS somehow to get it exact. I'm kind of a perfectionist on this stuff. That's why this problem is driving me crazy. lol

Yes, you can see the results of rod adjustment in VCDS if you make 3'rd gear WOT logs on boost (requested boost vs actual) and N75 duty cycle (group 011). Make the logs in same conditions before and after adjusting rod length.

 

[tyson]

Yes, you can see the results of rod adjustment in VCDS if you make 3'rd gear WOT logs on boost (requested boost vs actual) and N75 duty cycle (group 011). Make the logs in same conditions before and after adjusting rod length.

Thanks. For N75 duty cycle I'm supposed to aim for 75-80%?

 

[BuzzKen]

75-80% at 4000rpm

 

[tyson]

After many different tunes and a lot of frustration, I have a tune that is mild enough to be under the surge limits of my setup but the N75 duty cycle is now below stock. I'm now wondering if my VNT15 was surging before I swapped it out. A few people have told me that my stock exhaust is a huge factor and that my CAT may even be plugged up. I have a new MAF, new N75, New Vac lines, No boost leaks. I even put the stock airbox back on. Can anyone give me some ideas or confirm the exhaust issue. I can't be the only one who has put a 17/22 on with a stock exhaust...or maybe I am. I have a log but I'm new to forum use and am not familiar with posting images

 

[iwahn]

I had to gut my catalytic converter to make a gtb2056vl behave on my golf 99. The catalytic cell looked ok, but was way to restrictive.

 

[tyson]

I had to gut my catalytic converter to make a gtb2056vl behave on my golf 99. The catalytic cell looked ok, but was way to restrictive.

How was it behaving previously? Excuse my ignorance but how does that turbo compare to mine? thanks

 

[iwahn]

n75 duty cycle around 50% at wot, ie the vanes had to be keeped partly closed to keep the boost. Oscillating, pulsating boost pressure. The gtb2056 have a bigger turbine section compared to your, but is 3 generation vnt and fast spooling.

 

[tyson]

n75 duty cycle around 50% at wot, ie the vanes had to be keeped partly closed to keep the boost. Oscillating, pulsating boost pressure.

That's a glimmer of hope buddy. I hope that a new downpipe and CAT removal will help. I have the same N75 duty cycle numbers right now- maxing around 50-55. I was wondering if my N75 was reduced due to my tune bc we're trying to eliminate the surge or if this a consistent value that should be reaching close to 80% at 4000 rpms regardless of tune?

 

[iwahn]

I have looked at your video now. Your turbo does not behave exactly as mine. I had the symptoms at higher rpm´s, thought that can be related to differences in the boost and fuel maps. The n75 value is reflecting the position of the vnt vanes. When the ecu opens the vanes to lessen exhaust pressure on the turbine, the log will show high values. Low values at wot indicates løw differential pressure, the turbine is fighting against high back pressure from a restricting exhaust.

 

[tyson]

My timing is reading 50 - within spec but slightly advanced. I have ran logs and my actuator rod length is correct because requested and actual are very close. After talking to an people who actually are running this turbo above 4000 ft. I'm hearing that surge is unavoidable at low flow high boost RPM ranges. Mine happens to be 1900-2400 with my tune. After that point if I go WOT. I get no surge and plenty of boost up to 24/25 psi. I've been told a colt cam stage 2, porting my head, and/or an improved intake manifold will help. I just installed a 3" turbo back exhaust from KermaTDI and it's awesome and helped with the surge but I still have it.

Anyone reading this in a high altitude city thinking of putting on a VNT 17/22 BEWARE! Surge will get you. It will haunt you daily and it will be very expensive to eliminate. You'd be better off with an S7 or 17.

 

[faboka]

So is your 24/25 psi measured by a boost gauge or via VCDS?

 

[tyson]

Boost gauge

 

[storx]

couldnt a old air filter cause surge.... ? when was last time you replaced it?

 

[tyson]

I have replaced and swapped every combo possible on the intake. The best combo for me was the stock airbox with the snorkel with a Kerma 3" OMI. Fresh filter at time of turbo install. Unfortunately the surge is here to stay at this altitude with this turbo. Funny enough just installing the snorkel eliminated the barking of the turbo after go pedal let off. It was a huge difference on scary surge to manageable

 

[BuzzKen]

It's a 17/22. That's what they do. Nothing wrong with it.

troll

Where there's a problem there is a solution. If you don't have one, then don't divert my search for an answer by saying nothing is wrong...troll

-AFE intake, remove and replace with a stock airbox., just because it bolts on, doesn't mean it does any good.

I have replaced and swapped every combo possible on the intake. The best combo for me was the stock airbox with the snorkel with a Kerma 3" OMI. Fresh filter at time of turbo install. Unfortunately the surge is here to stay at this altitude with this turbo. Funny enough just installing the snorkel eliminated the barking of the turbo after go pedal let off. It was a huge difference on scary surge to manageable

Anyone reading this in a high altitude city thinking of putting on a VNT 17/22 BEWARE! Surge will get you. It will haunt you daily and it will be very expensive to eliminate.

Maybe I was just trying to help you.....

 

[tyson]

Thanks Buzz. I'd give you credit if you had come out and said hey this turbo is a great turbo, just not at your altitude. You may try limiting the intake flow a bit with the stock airbox. That AFE flows too much air and will increase your surge potential." Instead you left me bread crumbs

 

[BuzzKen]

Thanks Buzz. I'd give you credit if you had come out and said hey this turbo is a great turbo, just not at your altitude. You may try limiting the intake flow a bit with the stock airbox. That AFE flows too much air and will increase your surge potential." Instead you left me bread crumbs

My apologies for that, I'm always busy with a lot of emails to go through, I don't always have time for lengthy explanations. It is related to air density for sure, hot weather I find made it worse. I stuck with the stock airbox, intercooler and piping to keep it happy. Still made close to 195whp in the end, but I pushed her so hard it was boost creeping with the vanes wide open. A gtb1756vk kit from Ryanp was just as simple of a bolt-up install and a much nicer turbo overall. 17/22 is a great turbo though, they will take a beating, and I can't recall ever hearing of a failure.

 

[tyson]

Hey guys. Now that the surge is manageable, (It now just screams at me instead of buffeting, stalling then barking on spin down) I wanted your opinions on my actuator length as I can now start fine tuning things. Here's a log pic I had before and after a few additions. Not much is different in my eyes. I think I'm overboosting at high RPMs and was wondering if shortening the rod would help. I'm still around 51% at 4000 RPMs. Mind you I am 4500 ft above sea level. Thanks

 

[JFettig]

I have a feeling its due to the low torque tune(Stage 4.5 clutch saver) that its surging, not enough exhaust energy to force that large compressor to make the boost its requesting, Looks like its making a pretty good 15psi at 2000rpm which is probably about where you want it. The scream is normal.

Shortening the rod will make the overboost worse, send the latest log over to Malone, he can adjust the duty cycle to bring it into where it should be. The overboost isn't that bad, its more than requested but within safe limits.

 

[eddie_1]

Looks like your boost is still oscillating too much, that is why you are still squealing imo. Here are the boost curves between squealing and non-squealing from 2 different tuners and their approach to tuning 1722. You have to match the fueling well, not only the N75 map. Requires some work. Most tunes state side have the 'Dump and Chase' method like NA Ice Hockey. Overfueling to bring up the boost quickly. Listen to my 150mph video in link as I merge onto highway and floor it. There is hardly any squeal and still decent acceleration.

 

[jsrmonster]

Hi Tyson, I see 4 pages of posts telling you tune is bad and turbo is out of adjustment, but didn't see you comment about quality of smoke??

What is IQ at idle hot? How about posting or sending your tuner a vaglog of 001, 004, and 011 for a good 3rd gear pull.

Often times I get cars with severe underfueling. Nozzles are not actually what they thought they bought, and turbos bark like mad cuz there is nothing there to push the hot side, when the cold side is requesting more. You end up with a clogged exhaust (vnt requesting more energy that fuel can deliver) and a barking turbo. Have you driven it with maf unhooked, any differences? Under-reporting maf can make car run lean, as well as bad/under-reporting CTS. These problems are easy to spot in your vaglogs.

At your higher elevation I would expect your car would smoke heavy at 22psi with pp764's.

JFettig eluded to your problem it in post 53 about exhaust energy!

Jeff