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Discussion Starter #1
I have a problem with my s/c. I am not getting any boost anymore. If i bypass the vacuum its fine. I have checked for leaks. My gauge shows vacuum, but when i get on it never goes past 0.

Any ideas, really annoying.

Thanks
 

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Either the bypass is not getting vacuum to operate OR the bypass is getting vacuum, but its physically stuck. When you remove the vacuum from the bypass, it moves? I would think then that the vacuum source to the bypass is either kinked, collapsing, or disconnected. Check the line.
 

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Discussion Starter #3
Hmm, the lines look okay. I can manually move the bypass, Should i remove the vacuum while the car is running and see what happens?
 

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Yes. Plug the open hose (so you don't have a manifold leak), but leave the bypass' port open and see if it will boost.
 

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Discussion Starter #5
Well if i do that with the car off and then drive, it boost's very well. Better than when its working
 

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I know it will do that, it will help troubleshoot. If it is doing that, then it sounds like the bypass valve is functioning properly (by closing when there is NO vacuum). If its generating boost w/out a line hooked up, but no boost with the line hooked up, then its sounds like the problem is the vacuum source. Even if you can't physically see the vacuum line is damaged, try a new one. Sometimes the line will collapse without you being able to tell. so easily.

Without the vacuum line, its feels like it is more responsive because the boost is running constantly. The function of the bpv is to increase reliability and fuel consumption during normal throttle operation....so the engine isn't feeling like its racing all the time. The bpv helps more than it hurts for 99% of the time. You can always test the difference at the track.
 

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Discussion Starter #7
Thanks I will try replacing all the vacuum lines. Yea with the bypass discounnted my gas milage goes down the toliet.


Thanks
 

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Hello,

Sounds like the boost bypass actuator rod is hanging up on the heater hoses when the motor torques back. It will boost fine when the vacuum is disconnected because the actuator is already closed.

Thanks T.C.
 

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Discussion Starter #9
yeah i checked that and moved it abit. I tried manual moving the rod and it seems to move freely. It was fine before, well boost would come in late but it would close.

If it was a collapsed vacuum line wouldn't it boost all the time?


hmm?
 

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PSPTibby said:
yeah i checked that and moved it abit. I tried manual moving the rod and it seems to move freely. It was fine before, well boost would come in late but it would close.

If it was a collapsed vacuum line wouldn't it boost all the time?


hmm?
Hello,

Trust me, it is the actuator rod. Do you have mounts in the car?

Thanks T.C.
 

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Discussion Starter #11
Yea, i have the inserts.
 

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The manuals break those puny inserts more often than not. The autos can get away with it more since the shifting is quicker.

After thinking about it, it would boost more with a collapsed line. But you know its not the actuator, since it works in absence of vacuum. So it could be the rod which wouldn't be noticeably unless the engine torqued enough under load to bind it up.
 

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inserts are NOT mounts. get real mounts. i guarantee it'll solve ur problem. this 'problem' has been around since tc first started modding the alpine blowers.
 

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I agree with TC. sofakingrich's had nearly the same problem. We removed the sc, and I cut back his heater hose stubs anout 3/8" to 1/2" like I did mine, and it was fine afterwards. And inserts
S-U-C-K ! Get some good mounts.
 

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Discussion Starter #15
I cut the heater hose when I installed it. when I got it it would boost late. I willhave to check the insert. so what u r saying s when I get on it the engine torque backs and the rod can't move? if I got on gradly wouldn't it boost some?
 

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PSPTibby said:
I cut the heater hose when I installed it. when I got it it would boost late. I willhave to check the insert. so what u r saying s when I get on it the engine torque backs and the rod can't move? if I got on gradly wouldn't it boost some?
On mine, and sfr's, cutting a little extra heater hose was not enough. We cut the brass stubs on the fire wall back about 3/8 to 1/2". That extra clearance solved the problem. This may not be causing your problem, but it appears to be a common issue.
 

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Its just a tight fit. I had to have an turbo manifold welded and replace 5 times from it slamming against the firewall and cracking on a acura rsx.

Larger engines, esp. V6's, in sport compacts almost always have clearance issues when trying to add f/i. The heater hoses are a hit and miss. The inserts were an attempt at a cheap fix.

If you get on it enough to not torque the engine so the rod binds, but at the same time keep the throttle down enough for the bypass to close, then it would boost, but usually its one or the other that happens.
 

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Discussion Starter #19
Alright when i take it out today i will see if i can get it to boost with the vacuum hooked up.

Thanks
 
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