Wastegate hanging open??

[madadder]

If I am passing or just into the throttle and shift fast the car falls on its face like its just running on motor. The boost falls to nothing and if I keep my foot down it stays that way. Now if I granny shift then all is well, not to say that I am powershifting otherwise...just faster.

It has been doing this for a few years. I just try to remember to shift a little slower, but what is wrong with it anyway? Other than this the car runs fine. If anybody knows whats wrong how do I fix it?

[svobud]

that's a new one on me....never had that happen/or heard of that happening before. sorry I couldn't be more help. have you checked the waste gate? ya know - pulled it and inspected it? I know it's alot work just to look something over - but that's where I would start as well.

[DinomiteDave]

I am having the same problem

I have boost on the guage, can hear the turbo whining but have no power increase at all it actualy bogs out. What gives. the waste gate opens reall hard but it opens. I had the turbo rebuilt 2x's, replaced the oil slupply line, the oil sending unit, the valve cover gasket, had the catilatic converter checked had 3" from the cat to a flowmaster to 2.5" out, new plugs, wires test good with ohms meter, boost valve to a gillis valve, what am I missing?

[SvoTy]

Re: I am having the same problem

Originally posted by DinomiteDave
I have boost on the guage, can hear the turbo whining but have no power increase at all it actualy bogs out. What gives. the waste gate opens reall hard but it opens. I had the turbo rebuilt 2x's, replaced the oil slupply line, the oil sending unit, the valve cover gasket, had the catilatic converter checked had 3" from the cat to a flowmaster to 2.5" out, new plugs, wires test good with ohms meter, boost valve to a gillis valve, what am I missing?

Have you ever checked your fuel pressure? It could be leaning out on you under boost.

Also, check the hose from the back of the vane meter to the inlet on the turbo and make sure the spring wire is still in place. If it is not the hose will pinch shut under boost and cut the air off to the engine.

[madadder]

It only happens to me when I shift real fast. If I just put my foot down the boost comes on up to 12lbs and the needle stays right there( factory guage). And It will stay there until I let off. Now at that point if I shift fast it will fall on its *** like its NA. You can hear air rushing like a bastard put it must be going out the exhaust. I dont have a spring it my hose because it is a short shot between the 3" pipe that the bypass is hooked to and the turbo inlet, about 1 1/2". I had this problem before I added the bypass, if I remember right. its not often that I have to shift like that. well, not like I ever NEED to, but you know.

[svono50]

Madadder, You say you have a bypass and you can hear air rushing . . . I think you may have found your problem. When you let off the gas (i.e.- snap into vacuum from boost) your bypass opens up very quickly. It is possible your bypass valve is sticking open and killing your boost while your turbo pumps a ton of air through the bypass circuit. When you shift more slowly the bypass valve is not opened as quickly and doesn't get stuck.

Try removing the bypass valve and see if the problem continues. Might be worth a shot. Let us know what you find.

[madadder]

I'll give it a shot later by taking the vacuum line off the bypass and romping on it. Home alone with the rug-rat so I have to wait for my girlfriend to get home, but I will try it this afternoon.

[GT350R]

How did the BPV thing work out?

If it does not fix it, I had the SAME EXACT problem with my 84 GT. It was sucking the VAM hose shut. It would only do it if i shifted hard. They same thing. If I stayed in it it would not recover until I let off. I know you said you have a short hose, but at least it could help in trouble shooting it.

Also what style BPV do you have? I wonder if it could be getting pushed/sucked open? Does it have the same size inlet and outlet? Could you flip it around so that the force is on the side of the piston if its not already like that?

Lastly, you did say it did it before, so either it is a different cause with the same result. Such as the VAM hose sucking shut before and now the BPV.
OR, is it possible that the VAM is going off the scale? I never looked into it but it would be easy to check. Hook up a volt meter to it (pins and voltages are on my site) and see if it goes dead when it happens. Just a guess.

[madadder]

Been busy working on a room for my hot tub, so I haven't had time to get in the car. I did take it down town today with a short side trip.
Out of five full throttle quick upshifts, it only fell on its face once....boost guage still reading zero. I took my foot off the gas and quickly reapplied full throttle and nothing.
As soon as I get time I will run a full gammit of test situations and if I figure it out I will pass the info along.

[madadder]

Well I finally had some time to go run it a little. With the Bosch valve opening with the direction of the blown off boost it would drop boost pressure on quick shifts. I turned the valve around and it still did it. I then unhooked the vacuum line to the bypass valve and it still did it.
When the boost drops to zero, if I let off and get right back into the trottle it will not build boost. If I let off and wait a second or two and the hit the gas it builds boost again. I am starting to think that GT350R is right. MY hose from the VAM to the turbo has no coil in it. I am starting to think that snapping off and on the throttle isnt giving it time to open back up. BUT if this is the case why doesnt the hose close when I shift normal under boost??? And MY boost guage only reads a max off about 11-12 psi.
My cold air to the fender hose took a crap and right now I am running a K&N off the VAM. When I build a new set up I plan on having room to run the coiled hose again. Hopefully that will cure all. thanks, guys.

[madadder]

FINALLY !!!! I cut a 3" piece of exhaust pipe with a sawzall and compressed it smaller to fit in the VAM hose. Its tight, but I think it is holding the hose open all the time cuz I no longer have the boost loss problem and it has actually gone up from 11--12lbs to a full 15lbs. Everyone who said VAM HOSE, pat yourselves on the back cuz you were right!!!THANKS!!