So i got around to getting my car tuned by Jeff Evans last saturday and i managed to put down 525 hp/390 tq on 15 psi on pump. Test drove the car after the tune and felt pretty okay just still felt like something was funny. I get home and check things out and i found that the fuel pump hanger (Full Blown) was leaking fuel from the top of the housing through the brass fitting and i also found that the map sensor was leaking. Took the brass fittings out and put the anodized fittings in and changed the o-ring on the map sensor and fixed those issues. On the dyno Jeff managed to get a few WOT pulls but couldn't finish because the car kept spiking. The vacuum lines for the wastegates melted -__- so he told me to fix the issue and i should be good to go. I put stainless braided lines for the vac on the wastegates because nothing was holding up with all of that heat behind the turbo. Car STILL spiking to 23 psi, i have a 17 psi spring in both wastegates but heres the thing, When it spikes i am running rich at like 10.7 the car isn't leaning out which is good but it just doesn't make sense to me i don't know what else to do anyone know?

BTW None of this has to do with Jeff and his tuning its mechanical, my car just wasn't ready to be tuned apparently but he did the best he could and did help me out while i was getting the car tuned but he could only do so much lol

 

I looked at your progress thread quickly, looks like you have a boost controller and are using both ports on the waste gates?

what troubleshooting have you done?
First thing I would do would be to eliminate a mechanical issue with the waste gates. Unhook your Boost controller and hook up vacuum lines to the waste gates using a single port setup. If your spike is still there, it is a waste gate / boost creep issue. If it is not there, it is a vacuum line setup / boost controller issue. This assumes your MAP sensor is accurate and reading correctly, do you have a boost gauge through a separate source to verify?

You should also try to give us more info, like where in the RPM range is the spike? and how long does it last?

 

Well i did have a 4 port solenoid in place but jeff said they are a pain to work with and should've just went with a 3 port so we ran off of the compressor housing which would mean i should be boosting off of waste gate spring pressure but the thing is i have a 17 psi spring in both gates but he tuned at 15psi but now I'm spiking so I'm confused. I have not checked the wastegates yet I'm going to tomorrow. Im thinking of doing a boost leak test but that wouldn't make sense either because i would lose power not spike right?

 

I edited my post as you were replying. Get us some more information, like where it is spiking and how long it is spiking for.

If you do not have the boost controller hooked up and are indeed running off the compressor housing for a vacuum source to the bottom of the waste gates (note that being upside down, the bottom port would be the top for you), it sounds like boost creep.

 

I edited my post as you were replying. Get us some more information, like where it is spiking and how long it is spiking for.

If you do not have the boost controller hooked up and are indeed running off the compressor housing for a vacuum source to the bottom of the waste gates (note that being upside down, the bottom port would be the top for you), it sounds like boost creep.
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Sorry lol , so i have a 17 psi spring in both gates its spiking to 23 psi but my turbo doesn't hit full boost till 6500 so its like happening once it hits full boost. its happening up top at redline almost but the weird thing is that in 4th gear when i tried to see where it would spike to it boost cuts around 7000rpms and my air fuel is at 10.7ish.

 

I edited my post as you were replying. Get us some more information, like where it is spiking and how long it is spiking for.

If you do not have the boost controller hooked up and are indeed running off the compressor housing for a vacuum source to the bottom of the waste gates (note that being upside down, the bottom port would be the top for you), it sounds like boost creep.
[/quote]

Sorry lol , so i have a 17 psi spring in both gates its spiking to 23 psi but my turbo doesn't hit full boost till 6500 so its like happening once it hits full boost. its happening up top at redline almost but the weird thing is that in 4th gear when i tried to see where it would spike to it boost cuts around 7000rpms and my air fuel is at 10.7ish.
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6500 is pretty high to hit max boost, what size turbo?

You are definitely getting boost creep if it's happening in higher RPMs. Typically it is caused from undersized wastegates or poor manifold design. Double check your lines to the wastegates for leaks and check the diaphragms in the wastegates.

It is boost cutting because you're spiking PSI, above whatever your boost cut set point is (probably 18). You're rich, but you're not terribly rich, I target 11.5 on mine. If you do not have a PSI table higher than 15, the ECU will usually make imaginary linear lines based on your last 2 reference points; meaning if you are not tuned for anything above 15 PSI, that is why it is running rich, which is better than lean.

 

I edited my post as you were replying. Get us some more information, like where it is spiking and how long it is spiking for.

If you do not have the boost controller hooked up and are indeed running off the compressor housing for a vacuum source to the bottom of the waste gates (note that being upside down, the bottom port would be the top for you), it sounds like boost creep.
[/quote]

Sorry lol , so i have a 17 psi spring in both gates its spiking to 23 psi but my turbo doesn't hit full boost till 6500 so its like happening once it hits full boost. its happening up top at redline almost but the weird thing is that in 4th gear when i tried to see where it would spike to it boost cuts around 7000rpms and my air fuel is at 10.7ish.
[/quote]


6500 is pretty high to hit max boost, what size turbo?

You are definitely getting boost creep if it's happening in higher RPMs. Typically it is caused from undersized wastegates or poor manifold design. Double check your lines to the wastegates for leaks and check the diaphragms in the wastegates.

It is boost cutting because you're spiking PSI, above whatever your boost cut set point is (probably 18). You're rich, but you're not terribly rich, I target 11.5 on mine. If you do not have a PSI table higher than 15, the ECU will usually make imaginary linear lines based on your last 2 reference points; meaning if you are not tuned for anything above 15 PSI, that is why it is running rich, which is better than lean.
[/quote]

ahh that makes sense around 5500** not 6500 sorry, what would happen if i put a 10-12 psi spring in each gate would it help ? This would be after checking to see if the wastegates are opening properly

 

I edited my post as you were replying. Get us some more information, like where it is spiking and how long it is spiking for.

If you do not have the boost controller hooked up and are indeed running off the compressor housing for a vacuum source to the bottom of the waste gates (note that being upside down, the bottom port would be the top for you), it sounds like boost creep.
[/quote]

Sorry lol , so i have a 17 psi spring in both gates its spiking to 23 psi but my turbo doesn't hit full boost till 6500 so its like happening once it hits full boost. its happening up top at redline almost but the weird thing is that in 4th gear when i tried to see where it would spike to it boost cuts around 7000rpms and my air fuel is at 10.7ish.
[/quote]


6500 is pretty high to hit max boost, what size turbo?

You are definitely getting boost creep if it's happening in higher RPMs. Typically it is caused from undersized wastegates or poor manifold design. Double check your lines to the wastegates for leaks and check the diaphragms in the wastegates.

It is boost cutting because you're spiking PSI, above whatever your boost cut set point is (probably 18). You're rich, but you're not terribly rich, I target 11.5 on mine. If you do not have a PSI table higher than 15, the ECU will usually make imaginary linear lines based on your last 2 reference points; meaning if you are not tuned for anything above 15 PSI, that is why it is running rich, which is better than lean.
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its an s366 .91 a/r heres the dyno graph

 

No, lighter springs would not work. Exhaust gases take the path of least resistance. If the wastegates are undersized, it becomes easier for the gases to flow through the turbo rather than out the gate due to restricted volume/size of the gates. If it is a manifold design issue (position of wastegates), the exhaust gases 'skip over' the wastegates. This is usually from the wastegates being a 90* bend or greater from the natural flow of the exhaust gases. both effects get exaggerated in higher RPMs, due to the extra exhaust gas flow and the higher velocity of that flow.

Worth asking, do your dump tubes release to atmosphere or back into the exhaust?

pretty large turbo. Looks like your boost spike is happening at 7800 or so.

 

yea thats where its happening I'm dumping to atmosphere with screamer pipes coming off of the wastegates its a 90 degree bend right off the gates. The gates being upside down have no effect on the issue?