[MAINESUPRA]

I have a 1993 twin turbo automatic. What it is doing is it boosts to 5 lbs and then goes right back to 0. Will not go past 5 lbs no matter what i do and always gets cut back to 0. Anyone have any idea whats going on. Here is some background on the car. It was single turboed and put stock twins, the twins that came from car with only 61k miles back on car. Car has a Greddy BCC, Full Exhaust and Greddy 3 row front mount. It is on stock computer and does have EGR removed (could that cause a problem?) Any ideas or something to check or try would be greatly appreciated!

 

[Spdwrx_buffa]

boost leaks could cause this if i am correct.

 

[MAINESUPRA]

Hmm really? A leak or leaks would make it go back to 0? It wouldn't just stay at 5 if its all it could build with the leaks? Ill check for leaks but i don't hear any and hoses seem good. Maybe on the twins when i put back together but i think i would hear something

 

[Spdwrx_buffa]

it could also be a vacum leak which is easy to find. take a propane tank will a nozzle and while the car is running pass it by each vacuum line. when the car starts to race you found the leak.

 

[KThy2j]

on stock twins when i wasnt making any boost it was because of my wastegate.

 

[Fortunate One]

I kinda had the same problem when i was doing ETTC. I would boost 10 psi and it would drop to 5 or less.

I emailed Stu Hagen and this was his reply to me.

Please forgive the TTC part but you should get the idea.

In TTC both actuators are always open. In Seq, they are closed until the ECU tells them to open.

If one or the other is not opening, then you will see what you’re saying. Sounds like one of your actuators is not opening. Or you may have some bad hoses.

If any one of the 2 is not up to par, you will never see Boost past about 10psi.

The issue of dropping to 5psi might be the same results as a bad hose. Since it is rather inconsistent, you might have a tougher time finding it. Replacing As many hoses as you can will possible help.

You could actually have a VSV that is going out. This is another possibility. Only real way to check is To borrow another one and test it. Sometimes just checking their resistance values isn’t that accurate.

Hope this helps