The Project Pad

85oceanic wrote::rofl:

So on the mechanical side, that pretty much leaves the turbo itself, WG it self and/or Vacuum lines. SO just out of curiosity (correct me if I am wrong) is there where a ported cold side housing comes into play if this turns out to be some form of compressor surge happening?

I would run a pressure test to make sure there are no boost/vac leaks. Fluctuations in the wastegate reference signal could cause that.

Surge is a much more violent event (big spikes in your boost curve)

So you don't have the anti-surge housing? Just wondering. That would be my first thought with that tiny little hotside, but then it doesn't really go away on the top end like I'd sort of expect it to. It would be nice to have the ability to attach vemslog files to posts (hint, hint).

loxxrider wrote:It would be nice to have the ability to attach vemslog files to posts (hint, hint).

Just added the ability to attach .vemscfg and .vemslog files. Will need to add more extensions obviously, going to get the ECU config archive started.

EDIGREG wrote:

loxxrider wrote:It would be nice to have the ability to attach vemslog files to posts (hint, hint).

Just added the ability to attach .vemscfg and .vemslog files. Will need to add more extensions obviously, going to get the ECU config archive started.

AWESOME! I attached the first log I posted for those who want to check it out and give me some ideas.

Do you have that silly "condenser" thing installed in the vacuum line to the ECU? Sometimes they can act as a buffer to slight fluctuations. I've seen people with VERY aggressive cams have to add "filters" like these to get their cars to idle and run properly. This could be 100% wrong, but just an idea.

Here's what I'm talking about (Part 12):

Hmmm, ya I don't have #12. I never got it with my engine and harness either. Poop. Do I need one?

It's the moisture trap... you should run one to protect your ECU but I highly highly doubt that is your issue

click for more info: http://forums.quattroworld.com/s4s6/msgs/200368.phtml

EDIGREG wrote:It's the moisture trap... you should run one to protect your ECU but I highly highly doubt that is your issue

click for more info: http://forums.quattroworld.com/s4s6/msgs/200368.phtml

Yeah, was just a guess. I know that a container like that can sometimes buffer fluctuations when installed right before the map sensor.

Probably not the issue though.

Cool, thanks for the info Ed! I will definitely be getting one.

I just went out and took another log, still oscillates even with the revised vacuum lines. Grrr. I may just have to live it it.

It could definitely be that turbo. You've got another one coming anyway so who cares right?

It's not even just the top end, though it's much more noticeable up there. I am seeing traces of the oscillation starting around 3500 to about 5000 where its obvious then I'd say extreme 6500 onward.

Why/how would the turbo cause this? I've had surge in the past but no oscillation like this... Have another wastegate to try? Maybe there is something wrong with the diaphragm?

Don't give up already.

1) Boost/vac leak test
2) test wastegate diaphragm (make sure it holds vac)

amd is the best wrote:It's not even just the top end, though it's much more noticeable up there. I am seeing traces of the oscillation starting around 3500 to about 5000 where its obvious then I'd say extreme 6500 onward.

Why/how would the turbo cause this? I've had surge in the past but no oscillation like this... Have another wastegate to try? Maybe there is something wrong with the diaphragm?

I only have the one wastegate. :( There is a guy over on S2forums that has this same turbo, I am trolling through his thread to see if he experienced this. I am also posting a log that I JUST took with the revised vacuum lines. No change. :(

Just curios, what size vacuum line?

Also, is your carbon canister solenoid still in the car?

amd is the best wrote:Just curios, what size vacuum line?

If I remember correctly, it's 1/4 inch. I used semi-truck air-brake line and negative, the carbon canister is no longer in the car.

I agree it could definitely be a wastegate issue or some kind of strange boost leak.

Nick, it does look strange for surge. I don't have a lot of experience with surge, but I was under the impression that it typically happens around peak torque and then cleans up on the top end where the engine/turbo are really flowing. In this case, the exhaust side of that turbo *could* be the permanent restriction and thus you will see surge from peak torque on. It does look like it cleans up in one of those plots though. I don't have VEMStune on this computer yet so I can't see it in detail. I guess I need to get crackin'.

Definitely rule out wastegate or boost leak first. I'm just saying the turbo is a distinct possibility.

EDIGREG wrote:Don't give up already.

1) Boost/vac leak test
2) test wastegate diaphragm (make sure it holds vac)

I will check to see if the WG holds vacuum. I am still working on a way to pressure test the intake track. We don't have anything like that at work. :(

Just find some kind of rubber coupler thing that will fit on the intake of that turbo and then find a pvc cap to go on the end of that and tap in an air fitting. Easy!

You can get some basic plumbing/air schtuff from home depot or wherever. Should be able to rig something up easily.

loxxrider wrote:Just find some kind of rubber coupler thing that will fit on the intake of that turbo and then find a pvc cap to go on the end of that and tap in an air fitting. Easy!

Freakin good call. I will do that tomorrow!

Edit: SO I guess here is my other question, (correct me if I am wrong) but if it where indeed some kind of boost leak, wouldn't the actual boost levels matter? Because it does it whether or not I am running high boost.

I'd think that would have an effect on it too... but you never know. Stranger things have happened. It is never a bad thing to have a boost tester around either.

Seems really weird to me that it's happening with no boost control. I wonder if it's worth changing springs to a stock one or 1.9 bar and seeing if it goes away on the same boost with boost control.

It's crazy how fast it's oscillating too. From 14.7psi to 19psi back to 14.7psi in 1/5 a second.