# Wastegate flutter? Boost surge? Boost leak???



## Rento_VW (Jul 1, 2007)

My Current C2 30# file has this exact issue, boost would build up perfect, then once you hit your max boost it just fluttered. Never really found out what it was. Engine eventually started pouring blue smoke and coolant reservoir turned into a milkshake, checked compression and Cyl-1 was at 155psi and Cyl-3 was at 140psi with the other 4 at 160. Never over heated the engine...

Tearing the whole engine out and getting the block checked, hot tanked and honed, hope the head is straight and the cylinder walls are fine. Would've just bought another block, but being I bought the car with a bit over 35k and only put another 35 since I owned it, I want to keep the original motor in it...


Anyways, wondering if anyone wants to take a poke at what issue this could be.

Going C2 42# file this time and replacing/upgrading turbo parts. Might replace the wastegate, but we checked mine and couldn't find anything wrong with it.

Not my video, but here's the issue in some Mitsubishi Evo... Might upload my own in the next few days as I haven't really driven the car since Feb.


----------



## masterqaz (Oct 5, 2007)

Passed surge line. boost leak would do this also prob running pretty rich when it does it so it may blow spark. Bad diverter valve sealing issues also can result in this.


----------



## Rento_VW (Jul 1, 2007)

I'm really trying to remember what I did back around the beginning of the year that made the car run almost 100% perfect on a test run... I think I bypassed the waste gate.


----------



## masterqaz (Oct 5, 2007)

Yeah cause thats a solution to a problem. Test for a leak.


----------



## Rento_VW (Jul 1, 2007)

I'll run another leak test on the system before the rebuild and swap to 42# software, maybe that's what's causing the weird fluttering, would be nice to figure out the issue before doing a full rebuild only to get the same effects.


----------



## Poody (Jun 13, 2011)

Did you ever get this figured out? I think I'm having a similar problem with my car right now in gears 1-3. Car has a 1.8t running a PPT kit with a Precision 5558 journal bearing. It's currently running off of wastegate pressure on a TiAL MV-s (20 lb spring). Boost builds up just fine and as soon as the wastegate opens, boost is all over the place. It will jump from 20 to 5 to about 10 and then 0 and then holds 5 up to redline. It only happens when the wastegate has opened. If I let boost build to about 15 psi it comes on really nice and my BOV opens up just like it should, but as soon as it hits full boost it just goes nuts. 

Does that sound similar to your situation? 


Checked all charge pipe clamps and vac sources at the manifold and all of them are tight, switched to harder/softer wastegate springs, checked wastegate diaphragm for leaks, replaced spark plugs etc and nothing has helped. If you or anyone else has input that would be amazing


----------



## Rento_VW (Jul 1, 2007)

Sounds slightly different from issue. Also, no we never found out what's causing it.


----------

