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Discussion Starter · #1 · (Edited)
turbo lag please help!

hi i have a 94 tt auto and am currently bpu, problem is im not starting to build boost until 4500-5000 and not seeing full boost until around 5500-6000rpm [15psi no boost controller]. it iseems very laggy down low. ive checked the vaccum hoses and they look fine ive also disconected the wg completely and this does not change. there is no smoke or turbo whine. ??? familiar problem? any suggestions? thanks!
 

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Is your car running great other then that? Have you changed anything on it, in the past couple weeks.

goodluck
 

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Flash your ECU codes/check engine light to see if you have any codes. Post up what codes you have.
Next you'll want to check for a loose intercooler pipe connection. This might not be visible when the turbos aren't boosting (when in vacuum at idle), so you need to grab where 2 pipes connect and give a good tug on them to make sure they are connected well.
If all is well with that, check the hoses on your intake manifold and turbo VSV's to make sure none popped off.
Finally, check the resistance of your 'exhaust bypass valve', 'intake air control valve', and 'exhaust gas control valve' VSV's, as #2 turbo will act odd if any of those are bad.

Let us know what you find.
 

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Discussion Starter · #4 ·
no other problems. the car runs great otherwise and i should also mention that the vsvs are bypassed and its in ttc mode. thanks for all the help.
 

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Discussion Starter · #6 ·
yes and they all seem fine. i should ad that the car was sitting for nearly 3 years before i bought it too. not sure if that helps but there are no codes and the car runs great otherwise, just lots of lag and sometimes no boost in first gear at all other times it will make 10-12lbs but not until around 6k rpm ???
 

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what TTC method was used? Check valves or wiring the actuators open? Verify this is still in tact and both turbochargers are indeed working.

After that, you might want to do a compression test to make sure all cylinders are healthy...low compression can cause low boost in some cases.
 

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Discussion Starter · #8 ·
well i just bypassed the vsvs and capped them. but the car acted this way since i first got it bone stock and seems to respond the same in ttc or sequential mode. the compression was good 150-160 in all but the no.6 cylinder which only had 120. could that be it? the car does boost really strong but really late. bad wastegate? number one turbo? thank you for all info!
 

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Check to see if one of the two hoses popped off your pressure tank (under your intake manifold) or if the pressure tank is cracked. This could very well be your problem given what you have described so far. The proper way to go permanent TTC is to wire the actuators open. This eliminates the possibility of a vacuum leak preventing the #2 turbo from coming on. Good luck.
 
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