Stutters while going from vac to boost

[EuroGSTSpyder]

My 91 TSi is studdering and bucking a little ...When I floor it it runs perfectly, wehen I am at vaccum cruising it runs perfectly..but when I am a part throttle and it starts to climb it stutters some..mostly just when its about -5 to + 5...there in bwtween it stutters.
I did a boost leak test and found leaks at the the TB shaftseals but nothing else.

I also have a hissing sound in the intake manifold, sounds like its coming from inside the manifold and maybe its the TB seals that I hear there but if not..what can it be?

Any help appreciated casue I am putting on the rest of my powerstuff soon ( FMIC, turbo, inj, pump etc etc) and I was hoping to have it run smoothly before I start to tune it up.

Everything looks fine on the logger, but still stutters.

 

[karbon]

My car used to hesitate when going from vac to boost, and if I put just enough input to stay between both on the gauge, it felt like I didn't have much power. In other words, the transition seemed a little laggy or underpowered. I found out that I was running pretty stinking lean in the 400Hz range of airflow. I know you said your log looks fine, but that's my experience. Check and double check. Make sure you're in closed loop. Good luck.

 

[romeen]

I would repeat the boost leak test. How much did you pressurize your intake to when you did the test and how fast did it leak down? Are you using the soapy water out of a spray bottle technique to help identify the leaks? Check the injector seals too. Also, you may have had the intake and exhaust valves in overlap allowing the pressure to escape out of the exhaust.

Have you done any routine maintenance recently? If not consider replacing plugs, wires, any filters that may be questionable.

Also consider cleaning out your TB and intake manifold. You can use a spray cleaner and a rag to clean out the TB. I don't know if they have a product called Seafoam in Sweden but I have had very good results with it. I have used it on my car as well as friend's and family's. Everyone said that their car idled smoother afterwards and symptoms similar to yours were resolved.

 

[EuroGSTSpyder]

My car used to hesitate when going from vac to boost, and if I put just enough input to stay between both on the gauge, it felt like I didn't have much power. In other words, the transition seemed a little laggy or underpowered. I found out that I was running pretty stinking lean in the 400Hz range of airflow. I know you said your log looks fine, but that's my experience. Check and double check. Make sure you're in closed loop. Good luck.

This is exactly how it feels, when going from vac to boost it sags...no power really...hesitates.

Will check the log again.

I will aslo clean out everything and take another look when I am gonna put in the new stuff. Since I am putting in a new FMIC I will make sure everything is tight and sealed then. The TB will be removed anyways to change the seals so...hope it will work
The plugwires are brand new Magnecore 10mms but will check them too.

I also have a VR4 MAF in the car right now...maybe I will put my stock one back in and se if it makes any difference.

 

[Spoolin4Ever]

When my TPS was going out, it did that.

 

[EuroGSTSpyder]

lucky me then cause I have a brand new TPS as well as a brand new ISC as home Got them for free a couple of years back so...glad I kept them
Was gonna change them anyways just to make sure its ok everything so...might have to put them in then and see

 

[EuroGSTSpyder]

Hmmm..made a new boost leak test tonite..still same thing, only the TB se<ls that are leaking. Will have to order new ones..anyone know where to do that?

Anyways..I also tighten everything up regarding BOV hose, intake pipe ,pcv hose etc...and I changed the MAF back to my stock one ( instead of the Galant VR4 MAF I had in) and made sure everything was correct tightened.

Now the stuttering is gone and the car runs great!!! I have no idea if it was the MAF that was wrong or if it was something of the stuff I checked again....but hey.it runs as it should

 

[DSM_23]

have you crushed your bov?

 

[EuroGSTSpyder]

nope stock as far as I know..havent removed it and checked