Hey VF guys. I dropped some basic turbo questions a a few days ago and now I am back for more. But maybe it isn't so basic this time.

So my turbo on my 98 T5 seemed locked up to me; I was getting absolutely no boost and I was getting mad hesitation off the line ( to the point where I needed to basically pump the throttle to get the car to move). On top of that I felt like I was driving a messed up Saturn to give you an idea how fast I was accelerating. So I just assumed that the turbo was bad give the codes I had thrown.

But now I took off the turbo (mainly to see if I could actually do it myself) and found that the fans still spun very smoothly and did not move side to side at all.

But I did notice that my wastegate was being very stubborn. I'm by no means an expert on turbos or any sort of mechanical item so really don't know how a wastegate is supposed to act when not on a running engine but this one wants to fight me to move. Again I don't know if it is supposed to do this.

I also wanna say that I have a MBC hooked up but it hasn't given me problems so far.

Tech, anybody, help me out here. I don't wanna drop cash on a turbo if this isn't my problem.

Thanks in advance for any input.

 

The waste gate opens by pressure.
You need to add pressure to it for the waste gate to move.
Was any of the vaccum lines broke?
Are you sure you had the MBC hooked up correctly?

 

Figured that was it. Maybe the vac lines are screwed. I didn't hear air leaking though. I have it hooked up correctly cause I have been using it for quite some time.

Wouldn't I throw a code specifically for a messed up line? And if not what line would it likely be? The one off the CBV?

 

It shouldn't throw a code if you bypassed the Electronic Boost control.
The computer would never know you are in over boost or under boost.

I would check everything really good.
If you had no boost then I would say maybe waste gate hose or Vaccum source from the intake to the MBC.

 

I do need to chip this car because I want that BCS hooked up. That is my biggest hang up on a MBC.

Thanks a ton as always. I'll give it a check tomorrow.

 

You shouldn't.
I would say you have a vaccum problem.
It should work fine bypassing the EBC like on my 850.
I have a MBC and running 10 PSI boost.
But have it chipped as well but ran it like that before the chip.
I will have to try to get pics tomorrow night on how I have it set up.
I think you just blew a hose or something. Or maybe the wastegate valve went bad.

 

Haven't started it yet so I dunno if I will have the same problem. I will continue to update.

Hoses are all solid. But... which one goes where? Wastegate to mbc to ? And the one off the intake manifold?

Sorry but the diagram on the hood isn't helping.

 

how difficult was the wastgate door to open? It could be binding.

have you done a leakdown test with an air compressor on the intake system to check all the vaccume lines for a leak? It sounds like a bad leak to me.

Nick

 

Door opens just fine. Vac lines to turbo are also fine. Well fine enough not for me to loose all boost.

OK so where else should I check? What other lines could it be? Any off the intake? Im kinda stumped if it's a hose leak.

 

If all the hoses are good and the turbo spins good then it has to be a leak somewhere.

How do you have your MBC hooked up?

I have mine (Vac. source)from plastic vaccum tree on the intake to the MBC. Then from the MBC to the waste gate.

Is that how you have yours hooked up?

I wonder if your MBC is bad.

 

Now I'm not sure how I had it hooked up. That's why I asked about the vacuum lines and where they go. I don't have my mbc off my tree. Now I am not sure where it came from. I had it on a hose that was to the waste gate and then I don't know. I thought it was on the bottom of the turbo. I thought that the line from the intake mani went to the CBV? I don't know if that is right. Is there something I am missing? There has to be. It doesn't seem like that adds up.

That damn diagram on the hood gets more confused.

As for my MBC I have the Dawes unit. You know the brass-esque nut rotating one. I blew through it and it didn't let any air escape out the other end save for the tiny release hole on the side. I never tried to do that when it was new so I don't know if that is how it operates.

I am gonna do a little more research but tech let me know as soon as you can. You have been a huge help so far tech. Even if it is just the little things I have missed.

 

I put it all back together but I am still having the same problems. I am gonna do air test somewhere and maybe techs idea about the MBC is right. I might get a new one and try it out.

But my next question is... you have your MBC off the tree so...


That nipple on the bottom of the intake "snail"... do you have it capped or what? That is the only thing that is confusing me about your setup. If I can would cap that and be done with it.

FYI that diagram helped me a lot. Feel free to use that if you want.

 

Ok this is how I have mine hooked up.
See pics below.
Any quiestions just ask.






The hose going to the bottom is the one from the intake.