Boost problem! (w/ video!)

[T3hD0gg]

I first noticed this boost problem after I switched out my 710N diverter valve for a new one from ECS Tuning. It seems to stutter in any gear after third above 4k rpms after I go WOT starting in first. Once it gets up there, the boost will actually "stutter". It also sounds like the engine bogs a little bit when the boost jumps down.

Here's a nice video to show you what happens. I had to edit the video because I took it at night.

In the video the first few seconds is my car still in second gear. Then once it goes into vacuum and jumps back up, that's when I'm in third gear. It spikes to 17 psi and then tapers down to 14 psi then it starts doing the jumps between that and 9 psi.

Does anyone have the slightest idea what's happening and how to fix it? My mods are below if that helps a bit.

[biketsai]

Sorry, cant hear an audio in the video.
Maybe you have a boost leak? Im assuming you are just stock or chipped

[Seerlah]

This is just a new issue, or is it that you just never noticed it? Maybe one of the hoses for the dv is loose. I would check that first and make sure the clamps are extra tight.

[T3hD0gg]

Sorry, cant hear an audio in the video.
Maybe you have a boost leak? Im assuming you are just stock or chipped

There isn't any audio because my camera doesn't have a mic. It's just an old digital camera with "video capability." I guess I'll give my car a boost leak test this weekend but I don't think it'll help. I don't hear any sort of boost leak.

I have a Dahlback chip on the stock K03.

This is just a new issue, or is it that you just never noticed it? Maybe one of the hoses for the dv is loose. I would check that first and make sure the clamps are extra tight.

I'm pretty sure this is a new issue. When I first noticed it, I wasn't even looking at the boost gauge. I could just feel and hear it in the engine. It was only after it happened recently that I found out that the boost gauge actually jumps while it happens.

The noise is like... "vroooooom-oooom-oom-oooom-ooom" with each of those dashes being a pause and where the boost jumped down.

I'll be sure to check everything when I get home this weekend. Right now I'm on a college campus with no tools handy.

Thanks for the tips!

[T3hD0gg]

An update:

I've switched the old 710N diverter valve back in, replaced the DV vacuum line and I did an intake pressure test and there wasn't a single leak. But it still does this!! Anyone have any ideas? Do you know of any blocks I should try logging in VAG-COM?

I've logged misfires during these "attacks" and all cylinders stayed at zero. I logged timing retard across about a 15 minute drive with all types of load and the highest retarding I saw was 4.5 degrees.

Tomorrow I'm going to try logging my A/F, boost and also see if the throttle body might be closing.

Just looking for anyone who might be able to give me ideas!

[slopoke]

hmmm...ecu/plugs/coils?

[burner799]

I have the SAME EXACT issue, anybody got ideas?

[Bfiver]

try changin out your coilpacks... I had a faulty coilpack that wasnt blown but it would do almost the exact same studdering thing like i was hittin some kind of limiter... I change out the coild packs now it all good!

[Jibberific]

You said you don't have any boost leaks, so i'm gonna have to go with N75 on this one. When they are bad, the boost will constantly surge up and down when you are hard on the gas. That's what happened to me. They take like 15 minutes to swap out.

[T3hD0gg]

Since someone replied to this thread, I'll post up an update.

I found out the problem was that the throttle body was closing because boost was coming on too fast. I tried putting a MBC in parallel with the N75 and this managed to slow the boost build up enough that the throttle body wouldn't close but the boost would still shake between 18 and 20 PSI. I believe the only way to truly fix this would be to get an EBC.

FYI: This only happened during the winter or now during cold nights. Maybe the problem is the software? I have Dahlback. What do you guys have?